Tesi sul tema "Fruit yield"

Mangifera indica L. cv. Kent trees were subjected to five irrigation treatments during the 2000/2001 growing season with the aim of assessing the effects of irrigation on tree productivity and fruit quality. Two progressively reduced irrigation treatments (75 and 50% of the amount of irrigation water applied to the control), a control (100% field capacity), a regulated deficit irrigation (RDI) treatment and a farm control were compared with each other. Fruit yield, number and mean fruit weight were not significantly influenced by the different irrigation treatments. Peel colour and storage potential were improved in the reduced irrigation treatments. The RDI treatment improved the total soluble solids concentration (TSS) of fruits but increased the occurrence of split pit. Fruit firmness was not significantly influenced by the different irrigation treatments. In the second experiment, 'Kent' trees were covered with white shade netting of four mesh densities (50, 75, 100 and 125 g m-2) on a long¬term basis, while control trees remained uncovered. During the 2000/2001 growing season, light shading (50 g m-2) increased the yield and fruit numbers above that of control trees, while, heavier shading decreased the yield and fruit number below that of the control with the most dense net (125 g m-2) having the greatest affect. Peel colour, firmness and total soluble solids (TSS) at harvest were not affected by shading while the heaviest shade (125 g m-2) reduced storage potential of the fruit. Shading improved the appearance of fruits through the reduction of split pit, sunburn and wind damage. No fruit damage caused by bacterial black spot was observed in any of the shade treatments or the control.
Dissertation (M Inst Agrar (Horticultural Science))--University of Pretoria, 2006.
Plant Production and Soil Science
unrestricted

Groundnuts (Arachis hypogaea L.) grown in the semi-arid tropics are commonly exposed to air and soil temperatures> 35°C. This research in controlled environments has shown that continuous exposure of plants to hot air (day/night, 38°/22°C) and/or hot soil (38°/30°C) temperatures during the reproductive .phase (from flower bud appearance until reproductive maturity) significantly reduces total dry matter production, the partitioning of dry matter to pods and seed yields. The effects of hot air and hot soil temperature were additive and without interaction. Hot air temperature had no effect on flower production but significantlyreduced the proportion of flowers setting pegs (fruit-set) and hence the number of fruits. In contrast, hot soils significantly reduced flower production, the proportion of pegs forming pods and 100 seed weight. There was no evidence that plants dependent on symbiotic N2 fixation were more susceptible to heat stress than those dependent on inorganic N. Sensitivity to short (6 d) episodes of hot air temperature (38°/22°C) was acute during the period between 6 d before until 15 d after first flowering (OAF). The magnitude of that sensitivity depended on the number of floral buds exposed to heat stress before anthesis. In the Spanish cv. ICGV 86015, daytime air temperatures ~34°C imposed for only 6 d beginning at 9 DAF, significantly reduced flower number, pollen production and viability, fruit-set and seed yield. Fruit-set was most sensitive to heat stress during the first 6 h of the daylight period (AM). Warmer nights (28° cl 22°C) had no effect on flower numbers, but significantly reduced both pollen production and viability, and hence fruit-set. There were negative quantitative relations between flower number and day temperatures between 28° and 48°C. In contrast, reductions in fruit-set were quantitatively related to AM temperature >37.3°C. Pollen production and viability were also linearly reduced when day temperature was >34°C. These data will help plant breeders to screen germplasm and identify heat-tolerant cultivars, and should also improve simulation models of groundnut crops in the semi-arid tropics.

Thesis (MScAgric)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Olives have been produced commercially in the Mediterranean-type climate of the Western Cape region of South Africa since the early 1900’s. As in the rest of the world, South African table olive producers struggle with alternate bearing. Naphthalene acetic acid (NAA) has been used since the 1950’s to thin table olives in California. To date, South African producers opted to tolerate rather than try to reduce the negative effects of alternate bearing. However, due to increased olive production, profit margins are decreasing and producers can no longer ignore the negative effects of alternate bearing. Since the efficacy of NAA as a thinning agent is modulated by environmental conditions and genotype, trials were conducted to evaluate the use of NAA on locally important cultivars under South African conditions. The main aim was to establish optimum application rates for ‘Barouni’, ‘Mission’ and ‘Manzanillo’. NAA decreased the fruit number per tree, thereby improving fruit quality (increased fruit size and a higher proportion black fruit in the case of ‘Mission’) in all three cultivars. Thinning did not affect the return bloom in any of the cultivars. In the case of ‘Barouni’, the lack of a return bloom response could be due to the low level of thinning achieved, while climatic conditions during flower development may be to blame for the lack of response in ‘Mission’ and ‘Manzanillo’. Although NAA application did not affect the income per hectare, profitability may increase as harvesting costs account for roughly 50% of the input costs. Based on our results, NAA at 200 mg L-1, applied 10 to 15 days after full bloom, is recommended for local conditions. This concentration is slightly higher than the application rates used in California. An even higher NAA concentration might be used when premium prices are paid for large fruit, as in the case of ‘Mission’ and ‘Manzanillo’. However, NAA at 400 mg L-1 seemed to decrease vegetative growth in ‘Mission’, which may decrease bearing positions for the next season. Earlier application should be considered for a heavy “on” crop while the concentration can be decreased or the spray time delayed to decrease thinning when an average crop is anticipated. Gibberellic acid (GA3) was applied during an “off” season to ‘Mission’ and ‘Manzanillo’ to determine when during the season floral induction is inhibited by the simulated seed produced hormone. GA3 had its greatest effect on the extent of flowering in ‘Manzanillo’ when applied at the time of endocarp sclerification in early December. It follows from this result that to prevent the negative effects of a crop load on flowering in the subsequent season, thinning has to occur before endocarp sclerification. Later application of GA3 in January and February also decreased flowering, but to a lesser extent than application in December. These later applications possibly decreased flower initiation in buds on shoots that continued growing for longer or they may also have interfered with flower differentiation. The effect of the reduced “on” crop in the 2010/2011 season in GA3-treated trees on yield in the 2011/2012 season still needs to be determined.
AFRIKAANSE OPSOMMING: Olywe word sedert die vroeë 1900’s kommersieel geproduseer in die Mediterreense tipe klimaat Wes-Kaap streek van Suid Afrika. Soos in die res van die wêreld, is alternerende drag ‘n reuse struikelblok vir Suid-Afrikaanse olyfprodusente. Anders as in California waar naftaleenasynsuur (NAA) reeds vanaf die 1950’s gebruik word om tafel olywe uit te dun, het Suid-Afrikaanse produsente tot op hede die gevolge van alternerende drag verduur eerder as om die negatiewe effekte daarvan te probeer verminder. Weens ‘n afname in winsgewendheid vanweë ‘n toename in olyfproduksie kan Suid-Afrikaanse olyfprodusente egter nie meer langer die negatiewe effekte van alternerende drag ignoreer nie. Die effektiwiteit van NAA as uitdunmiddel word beïnvloed deur omgewingstoestande asook deur die plant se genetika. Gevolglik is proewe onderneem om die gebruik van NAA te evalueer op plaaslik belangrike kultivars en onder Suid-Afrikaanse kondisies. Die hoofdoel van die proewe was om optimale toediening konsentrasies van NAA vir ‘Barouni’, ‘Mission’ en ‘Manzanillo’ te bepaal. NAA het die vruglading per boom verminder en daardeur vrugkwaliteit (vruggrootte asook ‘n groter proporsie swart vrugte in die geval van ‘Mission’) in al drie kultivars verbeter. In al drie kultivars het uitdunning egter geen effek op die volgende seisoen se blom gehad nie. In die geval van ‘Barouni’ kan die swak opvolgblom moontlik toegeskryf word aan die lae vlak van uitdun terwyl klimaatstoestande tydens blomontwikkeling moontlik die oorsaak was vir die swak reaksie van ‘Mission’ en ‘Manzanillo’. Alhoewel toediening van NAA nie die bruto inkomste per hektaar verhoog het nie, kan winsgewendheid moontlik toeneem aangesien oeskoste ongeveer 50% van insetkostes uitmaak. Gebaseer op die resultate van die studie, word NAA toediening teen 200 mg L-1, 10 tot 15 dae na volblom, aanbeveel vir plaaslike toestande. Hierdie konsentrasie is effens hoër as konsentrasies wat in Kalifornië gebruik word. Selfs hoër NAA konsentrasies kan toegedien word wanneer ’n premium betaal word vir groter vrugte, soos in die geval van ‘Manzanillo’ en ‘Mission’. NAA teen 400 mg L-1 het egter vegetatiewe groei in ‘Mission’ verlaag en dit kan moontlik lei tot ‘n vermindering in draposisies in die volgende seisoen. Vroeër toediening moet oorweeg word wanneer ‘n groot “aan” oes verwag word, terwyl die NAA konsentrasie verminder of toediening uitgestel kan word ten einde uitdunning te verminder indien ‘n gemiddeld oes verwag word . Gibberelliensuur (GA3) is in die “af” seisoen toegedien op ‘Mission’ en ‘Manzanillo’ om vas te stel wanneer gedurende die seisoen saad-geproduseerde hormone blominduksie inhibeer. Die grootste effek op blominduksie van ‘Manzanillo’ is verkry met toediening tydens pitverharding gedurende vroeë Desember. Om die negatiewe effek van ‘n hoë vruglading op die volgende seisoen se blom te voorkom, moet vruguitdunning dus voor pitverharding geskied. Later toediening van GA3 in Januarie en Februarie het ook blom verminder, maar tot ‘n mindere mate as toediening in Desember. Hierdie later toedienings het moontlik blominisiasie van knoppe wat later gevorm het geïnhibeer of kon moontlik blomdifferensiasie negatief beïnvloed het. Die effek van die verlaagde “aan” jaar in die 2010/2011 seisoen in reaksie op GA3 toediening op opbrengs in die 2011/2012 seisoen moet nog bepaal word.

Thesis (MScAgric (Horticulture))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Persimmon production is new to South Africa with about 700 ha planted to the dioecious, parthenocarpic Triumph cultivar since 1998. Little local expertise is available to assist growers in achieving high yields of high quality fruit and previous research has shown that recipes that are followed in Israel, from where ‘Triumph’ was introduced to South Africa, do not necessarily have any beneficial effect in South Africa. ‘Triumph’ orchards in South Africa are often late in reaching full production. Persimmon trees are generally vigorous and prone to excessive fruit drop, partly due to excessive vegetative growth, especially when young and grown on the very vigorous Diospyros lotus seedling rootstock. The first objective of this study was to evaluate the use of growth retardants and various severities of girdling to increase flower formation, fruit set and yield in vigorous, young ‘Triumph’ orchards. Scoring and girdling improved fruit set and yield in two such orchards and are recommended as tools to improve yield in ‘Triumph’ in South Africa. Strapping, prohexadione-Ca (P-Ca) and paclobutrazol (PBZ) did not increase yield whereas 5 mm bark removal was too severe a treatment and decreased fruit quality in the current season and yield in the following season. None of the treatments had an effect on flower formation or decreased vegetative growth. PBZ, especially as foliar spray, appears to advance fruit maturity. P-Ca at 125 mg L-1 and 250 mg L-1 induced phytotoxicity symptoms and decreased yields in both orchards. However, further research is required before P-Ca and PBZ are completely discarded as treatments to manage vigor in ‘Triumph’ persimmon in South Africa. In contrast to the negative effect of excessive vigor on fruit production, the profitability of orchards is dependent on the rapid growth of trees after planting in order to fill the allotted canopy volume and achieve full production as quickly as possible. Hence, the second objective of this study was to determine optimum levels of irrigation and fertilizer application rates to attain early, high yields in newly planted ‘Triumph’. Fertigation was applied at three levels, viz. ½X, 1X and 2X with 1X being the commercial standard application rate. Irrigation was also applied at these levels without addition of fertilizer. In addition, fertilizer was applied at 0X, ½X and 1X at 1X irrigation level. Tree size increased with an increase in water application rate. Yield also increased linearly with an increase in water application rate due to a linear increase in fruit size. Fertigation and ½X water as well as an increase in fertilizer application rate at 1X irrigation substantially delayed fruit ripening. Hence, careful management of fertilizer and water application rate could be used to extend the harvesting period and, therefore, the marketing window of South African ‘Triumph’. We recommend that the trial be continued for a further few seasons so that the effect of water and fertilizer application rates on fruit quality and storability can be assessed. Fruit set may also be affected as trees reach their mature size with a concomitant increase in shading.
AFRIKAANSE OPSOMMING: Persimmonverbouing is ‘n nuwe bedryf in Suid-Afrika met ongeveer 700 ha van die tweeslagtige, partenokarpiese Triumph cultivar wat sedert 1998 aangeplant is. Min plaaslike kundigheid is beskikbaar om produsente van raad te bedien oor hoe om te werk te gaan om hoë opbrengste van hoë kwaliteit te verkry. Vorige navorsing het getoon dat resepte wat ‘Triumph’ van Israel na Suid-Afrika gevolg het, nie noodwendig suksesvol hier toegepas kan word nie. ‘Triumph’ boorde in Suid-Afrika neig om lank te neem alvorens hul hul maksimum produksievermoë bereik. Persimmons is oor die algemeen baie groeikragtig en geneig tot hoë vrugval, deels as gevolg van hul geil groei, en veral terwyl hulle jonk is en op die uiters groeikragtige Diospyros lotus saailingonderstam geënt is. Die eerste doelwit van hierdie studie was om die invloed van groei inhibeerders en verskillende grade van strafheid van ringelering op blomvorming, vrugset en oesopbrengs in jonk, sterk-groeiende ‘Triumph’ boorde te evalueer. Insnyding en ringelering met ‘n handsaag het vrugset en oeslading in twee groeikragtige boorde verbeter en word aanbeveel as geskikte ingrepe om die oeslading van ‘Triumph’ te verhoog. Draad-ringelering, en aanwending van prohexadione-Ca (P-Ca) en paclobutrazol (PBZ) het nie die opbrengs verhoog nie terwyl die verwydering van `n 5 mm strook bas té aggresief was en die vrugkwaliteit in die seisoen van toediening en opbrengs in die daaropvolgende seisoen verlaag het. Geen van die behandelings het blomvorming geaffekteer of vegetatiewe groei verminder nie. Dit wil voorkom asof PBZ, veral as blaartoediening, vrugrypwording kan versnel. Blare het tekens van fitotoksisiteit getoon na aanwending van P-Ca teen 125 mg L-1 en 250 mg L-1. P-Ca het ook die opbrengs in beide boorde aansienlik verlaag. Verdere navorsing is egter nodig alvorens P-Ca en PBZ sondermeer verwerp word as behandelings om die groei van ‘Triumph’ te beheer. Die winsgewendheid van boorde is afhanklik daarvan dat bome aanvanklik vinnig groei ten einde die toegekende boomryvolume so spoedig moontlik te vul en sodoende so vinnig as moontlik hul vol produksievermoë bereik. Bogenoemde is natuurlik teenstrydig met die negatiewe effek van uitermatige geil vegetatiewe groei op vrugproduksie. Die tweede doelwit van hierdie studie was dus om die optimale vlakke van besproeiing en bemesting te bepaal wat die vroeë aanvang van hoë opbrengste in nuwe ‘Triumph’ boorde sal verseker. Vloeibare bemesting is in kombinasie met besproeiing teen drie vlakke toegedien nl. ½X, 1X en 2X met 1X die kommersiële standaard vlak van toediening. Besproeiing is ook teen hierdie vlakke toegedien sonder dat kunsmis bygevoeg is. Addisioneel hiertoe is bemesting ook toegedien teen ½X, 1X en 2X teen 1X besproeiing. Boomgrootte het toegeneem met `n toename in die vlak van besproeiing. `n Lineêre toename in vruggrootte met ‘n toename in die vlak van besproeiing het ‘n oorsaaklike lineêre toename in opbrengs tot gevolg gehad. Bemesting in kombinasie met besproeiing, ½X besproeiing sonder bemesting, asook `n toename in die bemestingsvlak by 1X besproeiing het vrugrypwording substansieel vertraag. Die omsigtige bestuur van bemesting- en besproeiingsvlakke kan moontlik gebruik word om die oesperiode, en dus die bemarkingsvenster, vir Suid-Afrikaanse ‘Triumph’ te verleng. Ons beveel aan dat die proef vir ‘n vêrdere aantal seisoene voortgesit word sodat die effek van bemesting- en besproeiingsvlakke op vrugkwaliteit en -houvermoë bepaal kan word. Verhoogde oorskaduwing soos wat bome van sekere behandelings hul toegekende spasie bereik en oorskry, kan ook in die toekoms ‘n invloed op vrugset uitoefen.

Thesis (MSc .(Plant Production)) -- University of Limpopo, 2016
Delayed fruit harvest (DFH) or on-tree-fruit storage is a strategy being considered to extend the harvest season of late maturing ‘Reed’ avocado. However, avocado fruit growth beyond physiological maturity is accompanied by alterations in chemical and physical properties. Thus, the study aimed to investigate the effects of delayed harvest on tree productivity, mineral nutrition and post-harvest quality of late maturing ‘Reed’ avocado and further to evaluate the fruit quality response to varying ripening temperature regimes. As treatments, fruit were harvested early, mid and late in the season, with one month apart from each harvest during 2013 and 2014 seasons. Yield and fruit size were recorded at harvest. During each harvest time, two sets of fruit samples were collected to determine the fruit nutritional content while the second set was cold stored at 5.5°C for 28 days. After storage, fruit were ripened at 16, 21 or 25°C and evaluated for post-harvest disorders, pathological diseases and fruit physico-chemical properties. Yield dropped from 42 to 12 kg/tree from early to late harvest during 2013, while treatments showed no effect during 2014. Furthermore, treatments had no effect on fruit size during both seasons. Phosphorus content decreased by 40 and 23% from early to late harvest time during 2013 and 2014 seasons, respectively. Similar decreasing patterns were observed for K, Ca and Mg content. Zinc content remained constant during 2013; however, mid-season fruit maintained higher zinc levels during 2014 season when compared to early and late harvest time. Protein content was constant for early and mid-season fruit but significantly decreased during the late harvest in both seasons. Moisture content decreased from 74.0 to 65.0% from early to late harvest during both seasons. Starch, oil and ash content were high during late harvest time in both seasons; while crude fibre was high during the mid-harvest time when compared with early and late harvest time. Internal chilling injury increased with maturity and ripening temperature. In both seasons, higher temperatures induced higher anthracnose incidences during early and mid-harvest compared with late harvest time. Similarly, vascular browning was high on fruit ripened at 16°C during early and mid-harvest time but decreased on late harvest fruit during 2013. However, low ripening temperatures induced high incidences of vascular browning during 2014 season. Stem-end rot was high on fruit ripened at 16°C than 21 and 25°C during 2014 season. xvi Physico-chemical quality parameters showed similar behaviour in both seasons. Fruit lightness increased with ripening time regardless of ripening temperature during the early harvest, but remained constant during mid and late harvest. Hue angle (h0) and Chroma (C*) values were slightly reduced during ripening. Fruit ripened at 25°C had the highest respiration rate and reached a climacteric peak earlier (day 2) than fruit ripened at 21 and 16°C (day 4). Fruit firmness and weight loss were high and rapid at 25°C followed by 21 and 16°C regardless of the harvest time. Delayed harvest had no effect on yield and fruit size. Generally, nutritional content of avocado fruit increased with fruit maturity. Furthermore, fruit maturity played a major role in the response of fruit to ripening temperature. Higher temperature enhanced fruit ripening, but was conducive for development of post-harvest diseases. Keywords: Harvesting time, nutrition, yield, fruit size, ripening temperature, post-harvest quality

This study aimed to investigate and develop integrated crop management systems in organic glasshouse tomato production. The different management strategies that were used were tomato hybrid choice, grafting onto pest and disease resistant rootstocks, different fertiliser input types applied at several N-levels, steam disinfection of the soil substrate, chitin soil amendments and Milsana foliar disease control treatments. Four different experiments investigated the effects of these factors, as well as interactions between them, on the severity of a foliar disease Powdery mildew (Leveillula taurica), a soil-borne disease Corky root rot (Pyrenochaeta lycopersici) and nematodes infestation (Meloidogyne spp.). Tomato plant growth and yield parameters were also recorded in order to distinguish how the management practices that control plant pathogens affect growth and yield. Tomatoes are an important and significant source of nutrients and secondary metabolites which give a range of health benefits since many of the tomato micro constituents show antioxidative properties and have been linked with reduced risk of various forms of cancer and heart diseases. However, there is some evidence that the quality of tomato fruit is affected by hybrid choice, fertility management practices, grafting onto resistant rootstocks and the ripening stage at harvest. Therefore, tomato samples harvested from different trusses and at different ripening stages were analysed for quality parameters namely sugars, dry matter content and total antioxidant concentration. Of the two hybrids used in this experiment, Belladona plants grew slightly faster than 984 and produced many small fruit, while 984 plants produced fewer but bigger and heavier fruit. However, Belladonna and 984 did not show significant differences in their hydrophilic antioxidant activity although 984 fruit had higher sugar and dry matter content than Belladona fruit. Grafting onto the different rootstocks had beneficial effects on plant growth and reduced nematodes and corky root rot severity, but there were no significant effects on fruit antioxidants. The rootstock He-man F1 whilst shown to be more resistant against nematodes than R-5872 F1, was merely tolerant against corky root rot infection. On the other hand, the two rootstocks used had different effects on yield parameters. Grafting onto R-5872 F1 resulted in production of a larger number of smaller fruits, whilst grafting onto He-man F1 resulted in fewer, but bigger and heavier fruit.

The effects of controlled environment strategies on the yield and quality of cherry tomato fruit production were studied between April, 2003 and September, 2004 at The University of Arizona Campus Agriculture Center; Tucson, AZ. Two cultivars of cherry tomato (Lycopersicon esculentum Mill. var. cerasiforme) planted at 2.2 plants m-2 were grown hydroponically in coconut coir and drip fertigated with a low EC (2.4 dS m-1), high EC (4.5 dS m-1), mid day relief of high EC (2.4 dS m-1 or 4.5 dS m-1 over a 24 h period) or night time super high EC treatment (12 dS m-1). From April to October, 2003, the effects of mid day relief of high EC on cherry tomato fruit yield and quality were determined. From February through September, 2004 the effects of super high EC treatment, horizontal air flow (HAF) fan operation and/or delayed fertigation on cherry tomato fruit cracking were studied.

Deficiency of boron (B) in citrus has serious consequences for tree health and crop production. There is evidence that B deficiency may be a problem in Arizona citrus. Certainly, many symptoms of B deficiency are apparent, especially on the Yuma Mesa. A field trial was conducted at Yuma, Arizona to examine the effect of foliar boron application on fruit yield and quality of Citrus sinensis and C. limon. Boron was applied to 5 year old Citrus sinensis cv. Hamlin and C. limon cv. Rosenberger Lisbon trees at 5 different concentrations (0 ppm, 500 ppm, 1000 ppm, 2000 ppm, 3000 ppm) either before flowering or after flowering. At harvest, fruit yield and quality, and boron concentrations were determined. Foliar application appeared to increase leaf boron concentration (r= 0.50, p= 0.004). Fruit set was increased in Hamlin trees receiving bloom and post bloom applications of boron at the 1000 ppm level. Boron applications had no significant effect on lemon yield in these studies. This fruit set increase in Hamlin accounted for a 35% increase in overall yield relative to control trees. However, there was no significant difference in fruit weight, fruit pH, titratable acidity, peel thickness, juice volume, or soluble solid content of the fruits among treatments. Previous studies indicate that boron influenced in vivo and in vitro pollen germination in many crops. A plausible explanation for increased fruit yield may be that the applied boron was transported to the flowers where it exerted its influence of increased fruit set through an effect on pollen viability and/or pollen tube growth. However, clearly boron supplementation must be performed judiciously to avoid fruit drop from over -application of the element.

The importance of European honey bees in improving fruit set, yield and fruit weight of kiwifruit on the central east coast of Australia was investigated. Field investigations were carried out using different bee saturations and different types of male pollen parents. These investigations confirmed the importance of honey bees in kiwifruit fruit set, yield and fruit weight. However, the results suggested that increasing bee activity alone may not increase pollination of kiwifruit by honey bees. Many factors need to be understood before introducing bees into the orchard. Bees were more effective during the early part of the flowering period, and bee activity varied according to the sex of the vine, planting design and the time of day. The type of male pollen parents also influenced fruit size and quality. Flowers pollinated by different pollen parents were assessed for pollen tube growth and histochemical changes. The resulting fruit were also examined for weight and seed numbers. Honey bees play the major role in the size and yield of kiwifruit, but the design of male vines, their age and type of male pollen may also contribute. The kiwifruit pistil also possesses important features that can be considered as adaptations to insect pollination.
Doctor of Philosophy (PhD)

Thesis (MScAgric)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: Yield and fruit quality of Citrus species relative to foliar sprays of macronutrients Marginal fruit colour and poor internal quality have been primary problems in the production of early-maturing mandarins in the Western Cape region (34 Os t 9°E). This leads to a reduction in the percentage of exportable fruit, a delay in the picking and consequent reduction in internal quality due to over-maturity. Therefore, a well-developed rind colour and internal quality of citrus are quality parameters of major importance in the fruit market. The effect of soil-applied limestone ammonium nitrate (LAN) and foliar low-biuret on fruit colour, yield and internal fruit quality of 'Mihowase' Satsuma on 'Troyer' citrange rootstock were evaluated. A significant reduction in leaf N levels was recorded where soil N has been reduced from 168 kg N/ha per annum to 126 kg Nlha per annum. Nitrogen applications influenced internal quality, although differences between treatments were too small to be of commercial importance. Despite tree appearance being more yellow in some years where N was predominantly applied as foliar spray, no consistent reduction in fruit size or yield was found. There were no clear significant differences in fruit colour, probably due to the fact that leaf N-Ievels were still within or below the norms suggested for Satsuma. The effect of Seniphosf , a mineral mixture of 31Og/L P20S, 56g/L CaO and 30g/L total N, and mono-potassium phosphate (MKP) [52% P20Sand 34% K20] on fruit colour, yield and internal fruit quality of mandarins, viz., 'Mihowase' Satsuma and 'Nules' Clementine on 'Troyer' citrange rootstock were evaluated. Seniphos'" and MKP applied during autumn colour break also did not influence fruit colour, yield and internal fruit quality, viz., juice content (%), total soluble solids (TSS), titratable acid (TA) and TSS:TA ratio of 'Nules' Clementine and 'Mihowase' Satsuma. In the Citrusdal region of South Africa (Western Cape Province), rind roughness is a general problem which often limits the percentage of exportable fruits. The effect of foliar mono-potassium phosphate (MKP) applied at 3% or 5% and urea ammonium phosphate (UAP) at 2% at 4 or 6 weeks, respectively, after full bloom (AFB) on yield, internal and external fruit quality (rind texture) of Citrus spp on rough lemon rootstock were evaluated. MKP and UAP had no consistent effect on yield, juice content (%), TSS, TA and TSS:TA ratio of 'Nouvelle' tangor, 'Valencia' orange, 'Shamouti' midseason and 'Oroval' Clementine. MKP and UAP sprays significantly, but inconsistently improved rind texture of 'Nouvelle' tangor, 'Shamouti' midseason and 'Valencia' orange. However, no positive effect was found on rind texture of 'Oroval' Clementine and 'Eureka' lemon. Inconsistent effects ofMKP and UAP sprays were also found on % leafN, P and K.
AFRIKAANSE OPSOMMING: Opbrengs en vrugkwaliteit van sitrus spesies relatief tat blaar toedienings van makroelemente Marginale vrugkleur en swak interne kwaliteit is die prim ere produksieprobleme in vroee seisoen mandaryne in die Wes-Kaap (34 Os 19°E). Die gevolg is 'n lae persentasie uitvoerbare vrugte omdat die oesdatum uitgestel word wat 'n afname in interne kwaliteit veroorsaak weens oorrypheid. Goed ontwikkelde skilkleur en interne kwaliteit is dus van groot belang vir bemarking van die vrugte. Grond-toegediende kalksteen-ammonium-nitraat (KAN) en lae biuret ureum se effek op vrugkleur, oesgrootte en interne vrugkwaliteit van 'Mihowase' Satsuma op 'Troyer citrange' onderstamme is ge-evalueer. 'n Betekenisvolle afname van die N viakke in die blare is gevind nadat grondtoediening van N vanaf 168 kg N/ha/jaar na 126 kg N/ha/jaar venninder is. N toedienings het interne kwaliteit beinvloed, maar die verskille tussen die behandelings was nie van kornmersiele waarde nie. Al was die boomvoorkoms geler in sommige jare waarin N hoofsaaklik as blaarvoedings toegedien is, was daar nie konstante afnames in vrug-of oesgrootte nie. Daar was geen betekenisvolle verskille in vrugkieur nie, waarskynlik omdat die blaarvlakke van N steeds binne die nonne daarvoor in Satsumas was. Die effek van Seniphos ('n minerale mengsel van 310g/L P20S, 56g/L CaO en 30g/L totaal N en monokaliumfosfaat (MKP) [52% P20S en 34% K20] op vrugkleur, oesgrootte en interne vrugkwaliteit van 'Mihowase' Satsumas en 'Nules' Clementine op Troyer citrange onderstarnme is geevalueer. Seniphos en MKP, toegedien tydens kleurbreek in die herfs, het ook nie skilkleur of interne vrugkwaliteit (sappersentasie, totale oplosbare vaste stowwe (TOV), suurheid (TS) en TOV:TS) betekenisvol bemvloed nie. In die Citrusdal-omgewing in die Wes-Kaap Provinsie (Suid-Afrika) is skilgrofheid 'n algemene probleem wat die hoeveelheid uitvoerbare vrugte beperk. Die effek van blaartoegediende MKP teen 3 en 5% en ureum-amrnoniurn-fosfaat (UAP) teen 2%, op onderskeidelik 4 of 6 weke na volblom, is geevalueer ten opsigte van oesgrootte, interne en ekstenne (skil grofheid) vrug kwaliteit in Citrus spp op growweskilsuurlemoen onderstam. Nie MKP of UAP het konsekwente verskille getoon t.o.v. oesgrootte, sappersentasie, TOV, TS, of TOV:TS in 'Nouvelle' tangor, 'Valencia' orange, 'Shamouti' midseison of 'Oroval' Clementine nie. Skiltekstuur is egter betekenisvol, hoewel inkonsekwent, verbeter in laasgenoemde drie. Skiltekstuur van 'Oroval' Clementine en 'Eureka' suurlemoen is nie bemvloed nie. Blaarpersentasies van N, P en K is ook inkonsekwent deur MKP en UAP beinvloed.

In field experiments conducted in northern Virginia during 1998, oils reduced photosynthesis, fruit maturity, and crop yield. Three applications of a 1.5% (v/v) oil/water emulsion were made to Chardonnay and Cabernet Sauvignon vine canopies at 6200 L/ha (Chardonnay) and 2440 L/ha (Cabernet Sauvignon). Net assimilation rate (NAR), soluble solids concentration (SSC), and berry size were reduced by oil treatments when compared to an untreated control. Also in 1998, a 1.5% (v/v) oil/water emulsion at 5550 L/ha and 4680 L/ha was applied to 23 wine grape cultivars. Eleven cultivars had significant foliar injury but injury was not related to reductions in fruit maturity. Experiments conducted in 1999 determined if reduced spray volumes or applications to only the fruit zone minimize reductions in NAR and SSC. Chardonnay and Cabernet Sauvignon were treated with JMS Stylet oil (1.5%) using 5600 L/ha or 1870 L/ha applied to the whole canopy or 930 L/ha applied to the fruit zone. The NAR of 5600 L/ha treated Cabernet Sauvignon was significantly lower than the NAR of control and other oil treatments on three measurement dates. The NAR of Chardonnay in the 5600 L/ha treatment was significantly lower than the NAR of control treatments in three measurements. Cabernet Sauvignon SSC was reduced by the 5600 L/ha and 1870 L/ha treatments, relative to the water treated control, on three sample dates but not at harvest. The SSC of Chardonnay in the 5600 L/ha treatment was reduced at harvest as compared to all other treatments. The SSC of Chardonnay in the 1870 and 930 L/ha treatments was reduced relative to the water control. Low volumes of oil caused less reduction in NAR and SSC; however, there are concerns about the efficacy of oils used at low volumes due to poor coverage.
Master of Science

One red and one white cultivar of winegrapes grown in Southern Arizona was pruned to four different methods. The red cultivar was 'Merlot' and the white was 'Sauvignon Blanc'. The pruning methods were 2 bud spur, 4 bud spur, cane and basal buds only. The basal bud treatment was eliminated for 'Sauvignon Blanc'. The 4 bud spur method resulted in significantly greater yield when compared to the other methods. Fruit produced from the basal bud only treatment resulted in fruit that was significantly greater in pH and acid content. The 'Sauvignon Blanc' cultivar had significantly higher yield with cane pruning with no difference in fruit quality.

A field study was designed to determine if foliar boron (B) sprays could increase fruit set and yield of 'Parent Washington' navel oranges (Citrus sinensis). Treatments consisted of two application timings (prebloom and postbloom) and five application rates 0, 250, 500, 750 and 1000 ppm B as Solubor. Leaf B levels had a significant response to both application timing and rate. There were no significant difference in fruit quality or yield.

Vineyard management practices have an impact on grape berry development in ways that influence the quality of wine made from those grapes. The goal of this study was to determine whether exogenous applications of marine extracts on Syrah grapes can influence yield components, harvest juice quality parameters, and nutrient uptake. From 2009 to 2011, Syrah grape vines at the Trestle Vineyard on the California Polytechnic State University, San Luis Obispo campus received individual doses of marine extract via fertigation at berry set and veraison proportional to the amount they would receive on an annual per-acre basis based on the extract manufacturer’s recommended rate of application. In a separate experiment conducted in 2011, marine extracts were applied as foliar treatments. Treatments were analyzed for their effects on berry juice TSS, pH, TA, anthocyanins, tannins, and fruit yield per vine, clusters per vine, average berry weight, cluster weight, berries per cluster, vegetative yield, and foliar nutrient concentration. The marine extracts did not have any significant effects on yield components, harvest juice quality, or foliar nutrient concentration at any point in this experiment, except for a marginally significant increase in copper uptake with seaweed extract application as compared to the untreated control. Seaweed extract fertigation did result in a significant decline in net photosynthesis shortly after application as compared to control, while fish/seaweed extract blend fertigation resulted in a significant increase in net photosynthesis after application as compared to control. Though some minor effects of marine extracts were detected, there appears to be no benefit or drawback to applying these products in Syrah grapes growing in heavy clay soil in cool-climate conditions.

Okra is a nutritious vegetable that belongs to the family Malvaceae. It is widely grown in the tropical, sub-tropical, temperate and Mediterranean regions of the world. However, little evidence of the impacts of high temperature stress on various physiological, morphological, biochemical and metabolic processes is available for okra nor is the extent of genetic variation known. This study characterized and evaluated 176 diverse okra germplasm under constant high temperature to assess morphological and physiological changes to growth and development and to identify molecular markers linked to heat tolerance. In the process, the ploidy level and genome size of diverse materials were established. Significant marker-trait associations (MTAs) were found for various morphological and phenological traits. These included days to fruiting, plant height and stem diameter, that once validated, could be used for marker-assisted breeding. Fruit nutrient analysis identified significant genotypic differences for Ca, Fe, and Na and some organic metabolites including sucrose. The accumulation of Ca, Na and Fe and sugars in the fruit of some genotypes acted not only as osmolytes or protectants during fruit development, but also influenced signal transduction and the maintenance of cell membrane integrity. High temperature also impacted pollen micromorphology. Tolerant genotypes had dehisced anthers and fully turgid and spined pollen grains with improved germination compared to sensitive genotypes. The optimal temperature for pollen germination was observed to be 25°C while temperatures above 45°C caused significant damage. Flow cytometry indicated that the relative number of chromosomes varied from 84-189 and ploidy level from 7x to16x. The genome size data were inadequate to accurately indicate the number of chromosomes. A negative correlation between relative ploidy and genome size showed a downsizing of the genome with increased ploidy level.

This master-thesis presents an approach to track and count the number of fruit incommercial mango orchards. The algorithm is intended to enable precision agri-culture and to facilitate labour and post-harvest storage planning. The primary objective is to develop an multi-view algorithm and investigate how it can beused to mitigate the effects of visual occlusion, to improve upon estimates frommethods that use a single central or two opposite viewpoints. Fruit are detectedin images by using two classification methods: dense pixel-wise cnn and regionbased r-cnn detection. Pair-wise fruit correspondences are established between images by using geometry provided by navigation data, and lidar data is used to generate image masks for each separate tree, to isolate fruit counts to individual trees. The tracked fruit are triangulated to locate them in 3D space, and spatial statistics are calculated over whole orchard blocks. The estimated tree counts are compared to single view estimates and validated against ground truth data of 16 mango trees from a Bundaberg mango orchard in Queensland, Australia. The results show a high R2-value of 0.99335 for four hand labelled trees and a highest R2-value of 0.9165 for the machine labelled images using the r-cnn classifier forthe 16 target trees.

Studies on plant growth-promoting rhizobacteria (PGPR) and fungi (PGPF) as biostimulants have shown significant positive effects on plant health, fruit yield, or pest management. However, very few published studies to date have been specific regarding their effects on strawberries (Fragaria × ananassa), particularly on soilborne disease prevalence in organically grown strawberries. Empirical data on the results of using these products in commercial growing applications under various conditions would be highly valuable, especially for organic growers who have limited synthetic chemical pesticides, herbicides and fertilizers registered for use. The objective of this study is to evaluate the efficacy of biostimulant supplementation on strawberries for improving fruit yield, fruit quality, and plant health in both high-tunnel, open-sided ‘hoophouse’ and field conditions. This study consisted of two research projects. The first project investigated the effects of commercially available PGPR-based biostimulant products on strawberry plant health. The three products contained differing proprietary combinations of PGPR, primarily from the Bacillus and Lactobacillus genera. Plants were grown in two different soil types: sandy and clay, in order to investigate the effects of biostimulant supplementation in different soil conditions. In fall of 2018, 160 ‘Monterey’ strawberry plants were grown in an outdoor hoophouse in 3-gallon pots. Plants were either treated monthly with a single bacterial biostimulant product (EM-1, Accomplish LM, or Armory), or left untreated as a control. Plants were grouped into 20 blocks, each block comprised of 8 plants (each of the four treatments replicated in both soil types). Fruit yield (g), fruit sugar content (Brix), and leaf SPAD absorbance levels were measured weekly from January 27 to June 26, 2019. The treatments tested had no significant effects on fruit yield, leaf SPAD absorbance or Brix; soil type, however, did significantly impact fruit yield, with higher yields in sandy soil. The second project was a field trial beginning in spring of 2020, in collaboration with Rutiz Farms in Arroyo Grande, CA, involving a total of 480 ‘Chandler’ strawberry plants. The farm is organically managed and has a history of soilborne diseases, including Verticillium dahliae. These plants were either treated monthly with one of three microbial biostimulant products: a product containing a proprietary strain of Trichoderma harzianum biocontrol fungus (TrichoSym), and two of the same PGPR-based products used the previous year (Accomplish LM and Armory); or left untreated as a control. The experiment was laid out in a randomized complete block design with four blocks, with each block consisting of 4 plots for each of the 4 treatments; each plot contained 30 plants. Fruit yield (g) per plot was measured weekly throughout the 2020 growing season and phenotypic disease incidence was measured biweekly. Soil samples were taken at three different points throughout the season, cultured on selective media, and analyzed to obtain estimates of V. dahliae colony-forming units (CFU) per gram soil. The treatments tested had no significant effect on fruit yield, phenotypic disease incidence, or V. dahliae CFU/g soil. The results are inconclusive as to whether this lack of effect is due to viability of the products themselves, ineffective application techniques resulting in lack of rhizosphere colonization, or some combination of these. Further research is needed to determine whether or not supplementation with microbial biostimulants can produce reliable, beneficial results in strawberries.

A field study was designed to determine if foliar boron (B) sprays could increase fruit set and yield of 'Parent Washington' navel oranges (Citrus sinensis). Treatments consisted of two application timings (prebloom and postbloom) and five application rates 0, 250, 500, 750 and 1000 ppm B as Solubor. Leaf B levels had a significant response to both application timing and rate in 1998, but there were no significant differences in 1999. There were no significant difference in fruit quality or yield in either year.

Leaves are responsible for the majority of the fixed carbon in most plant species. Along leaf development, the photosynthetic capacity increases until the organ reaches maturity. Consequently, at the onset of senescence the leaves have the highest photosynthetic activity, then, as the chloroplasts are dismantled and the photosynthetic machinery is degraded, leaves gradually lose the rate of carbon assimilation. Although the capacity to fix carbon declines as senescence progresses, nutrient remobilization from macromolecule degradation nourishes the developing sink organs. In this regard, delaying leaf senescence stands out as a promising strategy to increase plant yield as extends the window of time with maximum carbon fixation rate. Another approach that is receiving much attention is the manipulation of chlorophyll degradation once it potentially regulates photosynthetic capacity and affects the nutritional quality of harvestable organs. As chlorophyll is degraded, the released phytol is recycled and can be either stored (i.e. as fatty acid phytyl esters), used for chlorophyll synthesis or be incorporated in tocopherol biosynthesis. Tocopherols have high nutraceutical value due to their antioxidant properties. However, the majority of the studies regarding senescence and chlorophyll degradation were carried out in the model plant Arabidopsis thaliana or grasses, creating a knowledge gap about these processes in fleshy fruit-bearing plants of human diet interest. In this regard, the tomato, Solanum lycopersicum, is an excellent model not only for the genetic and genomic resources, but also for its agronomic and nutritional importance. Thus, this project aims to extend what is known about the effects of chlorophyll degradation and senescence manipulation over the metabolism and yield of tomato plants, as well as fruit nutritional quality. In order to evaluate the consequences of alteration in chlorophyll degradation, first the enzymes chlorophyllase and pheophytinase, both capable of dephytylating the chlorophyll molecule, were identified and characterised. An extensive phylogenetic, evolutive and transcriptional analysis allowed the identification of two groups of chlorophyllases, one putatively involved in the response to different stimuli, while the other may act in chlorophyll homeostasis. As for pheophytinase, only one group was identified, being related to physiologically programmed processes that trigger chlorophyll degradation (i.e. leaf senescence and fruit ripening). Given this scenario, pheophytinase was chosen to be constitutively knocked-down in order to evaluate the effects over the metabolism of leaves and fruits. As consequence of this manipulation, transgenic plants were impaired in the leaf senescence-associated chlorophyll breakdown, but, although with an initial delay, fruit ripening-associated degreening was not compromised. Several photosynthetic and biochemical parameters were signs of photoinhibition, possibly due to a deficiency in chlorophyll recycling in leaves. This led to an increase in sugar exportation towards fruits, ultimately increasing soluble sugar content of ripe fruits. However, as a consequence, carotenoid levels were reduced, what, at least partially, it was compensated by an increase in tocopherol content. The results indicated that pheophytinase plays a role beyond senescence-associated chlorophyll degradation and its manipulation led to the development of fruit with increased soluble sugars and tocopherols at the cost of lowering carotenoid levels. Thus, these evidences support the manipulation of chlorophyll breakdown as a strategy for improvement of fleshy fruit plants. In order to address the effects of senescence over yield and fruit quality, the transcription factor ORESARA1, which has been widely characterised in A. thaliana and is considered a key regulator of senescence initiation, was targeted. After a comprehensive phylogenetic analysis and the characterization of the regulatory mechanisms, one putative ortholog was selected to be silenced. As consequence of this manipulation, leaves displayed increased chlorophyll content. Moreover, as senescence was delayed, the extent of photosynthetic activity of the leaves was also expanded. As the number of fruits was increased in the knockdown lines, this reflected in an increment in the harvest index. Ripe fruits accumulated more soluble sugars and tocopherols. Collectively, the results support the manipulation of leaf senescence as a strategy for tomato yield improvement. Altogether, data obtained enhance the knowledge about the impacts of chlorophyll degradation and leaf senescence over the metabolism of fleshy-fruit plants, providing strategies to increase yield and nutritional quality of fruits
As folhas, para a maioria das espécies vegetais, são o principal órgão responsável pela fixação de carbono. Durante o desenvolvimento foliar, o potencial fotossintético aumenta até a folha atingir a sua maturidade. Consequentemente, no momento que o programa de senescência se inicia, a folha apresenta a maior taxa de fotossíntese, a qual passa então a declinar conforme o cloroplasto se desorganiza e a maquinaria fotossintética é degradada. Apesar da redução na fixação de carbono, o catabolismo de macromoléculas possibilita a remobilização de nutrientes para os órgãos dreno em desenvolvimento. Neste contexto, atrasar a senescência destaca-se como uma promissora estratégia para aumento da produtividade, uma vez que estende o período de máxima fixação de carbono das folhas. Outra estratégia que tem recebido atenção por, potencialmente, regular a capacidade fotossintética e afetar a qualidade nutricional dos órgãos coletáveis é a manipulação da degradação da clorofila. Durante o catabolismo deste pigmento, o fitol liberado é reciclado podendo ser armazenado (i.e. na forma de ésteres de fitil com ácidos graxos), ser utilizado na síntese de novas moléculas de clorofila ou ser incorporado na rota biossintética de tocoferóis. Estes últimos compostos, por seu potencial antioxidante, possuem alto valor nutracêutico. No entanto, a maior parte dos estudos sobre senescência e degradação de clorofila foi realizada na planta modelo Arabidopsis thaliana ou em gramíneas, tornando escassas as informações relativas a plantas com frutos carnosos de interesse para a dieta humana. Nesse âmbito, o tomateiro, Solanum lycopersicum, é um excelente modelo de estudo não apenas pela disponibilidade de recursos genético e genômicos, mas também pela importância agronômica e nutricional desta espécie. Assim, este trabalho pretende expandir o conhecimento acerca dos efeitos da manipulação da degradação de clorofila e da senescência sobre o metabolismo e produtividade do tomateiro, bem como sobre a qualidade nutricional dos frutos. De modo a se avaliar as consequências de alterações na degradação de clorofila, iniciou-se por identificar e caracterizar em tomateiro as enzimas clorofilase e feofitinase, as quais catalisam a defitilação da molécula de clorofila. Uma vasta análise filogenética, evolutiva e transcricional permitiu a identificação de dois grupos de clorofilases, um dos quais estaria envolvido na plasticidade de respostas a estímulos e o outro na homeostase dos níveis de clorofila. Já para feofitinase, somente um grupo foi identificado, o qual está relacionado a processos fisiologicamente programados que levam à degradação de clorofila (i.e. senescência foliar e amadurecimento de frutos). Dado o panorama obtido, a feofitinase foi escolhida para ser constitutivamente silenciada de modo a se avaliar as consequências para o metabolismo de folhas e frutos. Como consequência do silenciamento, as linhagens transgênicas mostraram-se incapazes de degradar clorofila durante a senescência, mas, embora com um atraso nas etapas iniciais, a degradação ao longo do amadurecimento de frutos não foi comprometida. Diversos parâmetros fotossintéticos e bioquímicos foram indicativos de fotoinibição, possivelmente em virtude de uma deficiência na reciclagem da clorofila em folhas. Isto acarretou em um aumento na exportação de açúcares para frutos, incrementando a concentração de açúcares solúveis nos frutos maduros, que, em contrapartida, resultou na queda nos teores de carotenoides. A queda nestes compostos antioxidantes foi, ao menos parcialmente, compensada por um aumento nos níveis de tocoferóis. Os resultados indicaram que a feofitinase possui um papel além da degradação de clorofila associada à senescência, e que sua manipulação leva ao desenvolvimento de frutos com maior teor de açúcares solúveis e de tocoferóis ao custo da redução no de carotenoides. Desta forma, estas evidências suportam a manipulação da clorofila como estratégia para o melhoramento de frutos carnosos. Para investigar o efeito da senescência sobre a produtividade e qualidade de frutos foi escolhido o fator de transcrição ORESARA1, o qual está amplamente caracterizado em A. thaliana e é considerado um regulador chave no desencadeamento deste processo. A partir de uma extensa análise filogenética e da caracterização de sua regulação, um putativo ortólogo foi selecionado como alvo para silenciamento. Como consequência desta manipulação, folhas apresentaram os níveis de clorofila incrementados. Além disto, taxas fotossintéticas maiores que as do genótipo controle foram mantidas por maior tempo indicando que a iniciação da senescência foi retardada. Assim, estas plantas produziram um maior número de frutos, consequentemente, aumentando o índice de colheita dessas linhagens. Os frutos maduros apresentaram maiores teores de açúcares solúveis e de tocoferóis. Os resultados demostraram que o retardo do início da senescência é uma estratégia efetiva para aumento da produtividade de tomateiro. Coletivamente, os resultados obtidos aprofundam o conhecimento acerta dos impactos da degradação de clorofila e senescência sobre o metabolismo de plantas com frutos carnoso, além de prover estratégias para se incrementar a produtividade e a qualidade nutricional de frutos

Thesis (MScAgric)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Three field trials were conducted to investigate the effects of mulching on the chemical and biological aspects of the soil as it is reflected by tree performance and fruit quality in ‘Cripps’ Pink’ orchards. In the two trials at Lourensford Estate, where only the soil type differed between sandy silt loam (sandy) and heavy silt loam (heavy), mulches where used as an additive to the soil surface together with a standard, commercial, inorganic fertilization program. Four different mulch types: compost, wood chips, vermi-compost and a geotextile fabric, were compared to a bare surface control in a randomized complete block design. At the heavy silt loam site (site 1), the wood chips treatment was the most effective in regulating diurnal soil temperatures in the top 10 cm of soil (2009/10), whereas all mulches regulated average diurnal soil temperature similarly and more effectively than the control at the sandy silt loam site (site 2). After two seasons of treatment at site 1, the vermi-compost treatment significantly increased soil phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), manganese (Mn), zink (Zn) and boron (B) significantly compared to the control. The wood chips treatment increased Na, K and Ca and compost only increased soil K significantly compared to the control. For site 2, only wood chips (Na and K) and vermi-compost (Na, K and Mg) showed significant increases in soil nutrient elements compared to the control. Yield efficiency was significantly increased by the wood chips (both seasons) and vermicompost (only 2009/10) treatments compared to the control in site 1. In site 2, none of the treatments differed significantly in yield efficiency compared to the control treatment. The number of roots and fine feeder roots were increased (not sign) by the wood chips and geotextile treatments compared to the control. In site 1, all treatments improved the number of roots compared to the control treatment, in contrast with site 2, where the number of roots of the control, compost and vermi-compost treatments was more similar. Fruit quality showed significant differences between the wood chips and vermi-compost treatments compared to the geotextile and control treatments for malic acid, at site 1, at harvest in 2009. This did not differ significantly from the compost treatment. Leaf mineral analysis only showed significant differences at site 2, in 2010, with significantly increased for the following minerals and treatments: Mn (compost and geotextile treatments versus other treatments), Fe (control treatment compared to all treatments except compost), Zn (compost compared to all other treatments) and B (control and compost versus vermicompost, wood chips and geotextile). Fruit mineral analyses showed no differences between treatments at harvest 2009 for either site and 2010, for site 1. At site 2, the Ca percentage of fruit from the wood chips treatment was significantly higher than that of all treatments, except the geotextile treatment. Only in the 2010 analysis at site 2, the mycorrhizal colonization was significantly influenced, where all the mulching treatments showed an increase compared to the control. However, the same trend was observed at site 1. At site 1and 2, the compost, wood chips and vermi-compost treatments in general showed a decreasing trend in percentage plant parasitic and increasing trend in percentage free living nematodes from 2009 to 2010. In general, the geotextile and control treatments showed an increasing trend in the percentage plant parasitic and decrease in percentage free living nematodes. However, this was not the case at 0 – 15 cm soil depth for site 1. In the third trial, at Elgin Experimental Farm (Elgin), bare surface chemical control was compared to mulching in the tree row (mulch) and mulching together with regular application of compost tea (mulch + compost tea). All treatments were combined with different inter row management practices to compose a total of eight different treatments. In the tree row, the control treatment received standard rates of inorganic fertilizer, which was compared to the mulched only treatment. Both the percentage of soil carbon and cation exchange capacity was significantly increased by all the mulch treatments compared to the control. Furthermore, all the mulches increased various soil minerals significantly, however of which only P was significantly increased in both the leaves and fruit. The rate of soil microbial activity and mycorrhizal root colonization was significantly increased by mulching treatments, but resulted in a significantly lower yield efficiency compared to the inorganic control treatment. This can be ascribed partly to the microbial activity of the compost mulch during spring, although it was not quantified per se and to the increase in tree vigour at the end of the trial. The slow rate of N mineralization was reflected indirectly by the significantly lower fruit N for the mulched treatments and the lower rate of microbial activity during spring at this site. With regards to the addition of the compost tea, no significant contributions were evident in terms of tree performance, soil minerals or microbial activity over a period of seven years, compared to the application of mulch only. Compared to the trial at Lourensford Estate, with no significant differences in fruit mineral composition between treatments after two years, fruit mineral analyses of the Elgin trial showed significant differences between treatments after six (2009) and seven (2010) seasons for P for some treatments. Only in 2010 more treatments showed significant differences for N, Mn, Fe and Zn as well. Regarding fruit quality, in agreement with the results at Lourensford Estate, differences were not persistent across all seasons for treatments.
AFRIKAANSE OPSOMMING: Veldproewe is geloods om die effek van verskillende deklae op grond chemiese en – biologiese aspekte en die effek daarvan op boom prestasie en vrugkwaliteit in ‘Cripps’ Pink’ appelboorde te ondersoek. In die eerste twee proewe te Lourensford Landgoed, waar slegs die grondtipe verskil het tussen die sanderige slik leem (ligter) en swaarder slik leem (swaar) gronde, is deklae toegedien saam met ‘n standard bemestingsprogram en mikro-besproeiingstelsel. Vier deklaagtipes: kompos, houtspaanders, vermi-kompos en geotekstiel material, is vergelyk met die onbedekte, skoon bewerkte, kontrole in ‘n total ewekansige blokontwerp. By die swaar grondtipe (perseel 1), was die houtspaanderbehandling die effektiefste om die daaglikse skommelings in grondtemperatuur te reguleer in die boonste 10 cm, teenoor die sanderige perseel (2), waar al die deklae die daaglikse grondtemperatuur meer effektief as die kontrole behandeling gereguleer het. By perseel 1, het die vermi-behandeling ‘n betekenisvolle toename getoon teenoor die kontrole behandeling in grond fosfaat (P), kalium (K), kalsium (Ca), magnesium (Mg), natriuim (Na), mangaan (Mn), sink (Zn) en boor (B). Alhoewel dit nog nie tans gekwantifiseer kan word nie, is ‘n gedeelte van die toename heel moontlik te wyte aan die samestelling van die deklaag. Die houtspaander- en komposbehandelings het ‘n betekenisvolle verskil in toename tot gevolg gehad in grond K en Na in vergelyking met die kontrole. In die geval kan die toename van die komposbehandeling aan die invloed van die sampestelling van die deklaag toegeskryf word, maar nie in die geval van die houtspaanderbehandeling nie. Die geotekstielbehandeling het, soos verwag, nie betekenisvolle verskille ten opsigte van die kontrole getoon nie, aangesien die samestelling van die geotekstielmateriaal nie voedingstowwe tot die grond kan toevoeg nie. By perseel 2, het beide die houtspaander- en geotekstielbehandelings betekenisvolle toenames in grond elemente (K, Mg) getoon teenoor die kontrole behandeling. Die ander elemente het nie noemenswaardige verskille teenoor die kontrole getoon nie. Weer eens kan die toename in die vermi-kompos toegeskryf word aan die samestelling van die deklaag, maar nie in geval van die houtspaanders nie, wat ‘n moontlike rol van ander faktore soos temperatuur en grondvog in die opname en beskikbaarheid van voedingselemente toon. Op 30 cm diepte in perseel 1, het die vermi-kompos behandeling betekenisvolle hoër Na, K, Mg en P getoon as die kontrole. Die houtspaanderbehandeling het betekenisvolle hoër Na, K en Ca getoon as die kontrole. Geen een van die ander behandelings het enige betekenisvolle veranderinge ten opsigte van voedingselemente getoon nie. Vir perseel 2 by die gronddiepte, het die houtspaanderbehandeling betekenisvolle toenames in grond Na en K getoon teenoor die kontrole. Geen van die ander behandelings het enige betekenisvolle veranderinge ten opsigte van voedingselemente getoon nie. By hierdie dieper gronddieptes is ‘n soortgelyke verandering in elemente waargeneem as by die vlakker gronddieptes vir perseel 1, in geval van P en K. Mg en Na het volgehoue verandering vir die vermi-komposbehandeling in die dieper gronddieptes getoon vir die makro-elemente, maar nog nie in geval van mikroelemente nie. In perseel 2 – het toenames in K en Mg in die vermi-komposbehandeling ook voortgeduur en die veranderinge vir beide persele mag toegeskryf word aan die samestelling van die deklae per se. Dit blyk dat die veranderinge in die komposbehandeling nie so konstant voorgekom het in die materiaal wat in die proewe toegedien is nie. Nietemin kan die kompos- en vermi-komposbehandelings ook ander grond faktore beïnvloed en die bydra van die minerale elemente afkomstig uit die samestelling van die deklaag moet eers bereken word alvorens afleidings gemaak word. By beide persele het die komposbehandeling die opbrengseffektiwiteit verminder in vergelyking met die kontrole behandeling. Die opbrengseffektiwiteit is betekenisvol verhoog in die houtspaanderbehandeling (beide seisoene) en vermi-komposbehandeling (net 2009/10) in vergelyking met die kontrole in perseel 1. In perseel 2 het teen behandeling betekenisvol in opbrengseffektiwiteit verskil ten opsigte van die kontrole nie. Die aantal wortels en fyn, voedingswortels het ‘n dramatiese (nie-betekenisvolle) toename getoon by die houtspaander- en geotekstielbehandelings. In perseel 1 het alle behandelings die aantal wortels verhoog ten opsigte van die kontrole in kontras met perseel 2, waar die aantal wortels in die kontrole, kompos- en vermi-komposbehandelings ongeveer dieselfde was. Stamwaterpotensiaal het onveranderd gebly ongeag van die behandeling, wat moontlik beïnvloed is deur die hoë besproeiingskedulering siklus. Geen verskille tussen behandelings of persele is gevind nie. Alhoewel dit net in die tweede seisoen (2010) gemeet is, was daar geen betekenisvolle verskille in gemiddelde loot groei van eenjaarlote tussen die behandelings of persele nie. Vrugkwaliteit het betekenisvolle verskille getoon in appelsuur (malic acid) in die houtspaander- en vermi-komposbehandelings teenooor die geotekstie- en kontrole behandelings in perseel 1, by oes 2009. Laasgenoemde het nie betekenisvol van die kontrol behandeling verskil nie. Hierdie verskille het nie na opberging voortgeduur nie. Geen betekenisvolle verskille in vrugkwaliteit het voorgekom by perseel 2, tydens oes, of na opberging nie. Gedurende oes 2010, asook na opberging, is geen verskille in vrugkwaliteite van enige persele opgemerk nie. Behandelingsverskille in blaar-analises is waargeneem tussen vermi-kompos- en die ander behandelings, met uitsondering van die geotekstielbehandeling in Februarie 2009, perseel 1. Geen ander betekenisvolle verskille vir enige element het voorgekom tussen behandelings in perseel 2 nie. Gedurende 2010 is geen betekenisvolle verskille tussen behandelings ten opsigte van blaar-analises gevind vir perseel 1 nie. Betekenisvolle verskille in blaar- en vrugmineraal-analises was in perseel 2 teenwoordig as volg: Mn (kompos- en geotekstielbehandelings teenoor al die ander behandelings), Fe (kontrolebehandeling teenoor alle ander behandelings behalwe die komposbehandeling), Zn (komposbehandeling teenoor al die ander behandelings) en B (kontrole en komposbehandelings teenoor vermi-, houtspaander- en geotekstielbehandelings (gedurende 2010. Die vrugmineraal-analises het geen verskille getoon tussen behandelings by oes 2009 vir enige perseel, of 2010 vir perseel, 1 nie. By perseel 2 was die Ca persentasie in die vrug in die houtspaanderbehandeling betekenisvol hoër as die van die ander behandelings, uitgesonder die geotekstielbehandeling. By perseel 1, het al die behandelings die persentasie mycorrhiza-kolonisasie verhoog in vergelyking met die kontrole, alhoewel dit nie betekenisvol was nie. By perseel 2 was daar wel ‘n betekenisvolle toename in die persentasie mycorrhiza-kolonisasie by al die deklaagbehandelings in vergelyking met skoonbewerking van die kontrole behandeling. Die persentasie plant-parasitiese nematodes was baie variëerend met gronddiepte by beide persele. Die houtspaander- en vermi-komposbehandelings in perseel 1 het ‘n afwaartse tendens getoon in die persentasie plant-parasitiese en toename in persentasie vry-lewende nematode vanaf 2009 na 2010, in die 0-15 cm diepte. In teenstelling, het die geotekstiel- en komposbehandeling ‘n toenemende tendens getoon in die persentasie plant-parasitiese en klein afname in persentasie vrylewende nematodes vanaf 2009 tot 2010. Geen betekenisvolle verskille in nematode getalle is waargeneem in gronddiepte 15 -30 cm grond in die perseel nie. In perseel 2 is geen betekenisvolle verskille in aantal nematodes gevind gedurende die twee seisoene tussen behandelings of binne persele op 0-15 cm gronddiepte nie. Nietemin het die houtspaander-, kompos- en vermi-komposbehandelings die persentasie plant-parasitiese verlaag en die van die vry-lewende nematode verhoog vanaf 2009 tot 2010, in vergelyking met die kontrole in die 15-30 cm gronddiepte. Slegs die houtspaanderbehandeling het betekenisvolle verskille getoon teenoor die kontrole. Die geotekstiel- het dieselfde tendens as die kontrole behandeling getoon, met ‘n toename in persentasie parasities- en afname in persentasie vry-lewende nematode. Die kontrole en geotekstielbehandelings het nie betekenisvol van mekaar verskil nie. Die aantal erdwurms en meso-fauna was baie laag tydens die eerste twee jaar by beide die persele en data is daarom nie statisties verwerk nie. By die derde proef, is ‘n skoonbewerkte oppervlak, wat chemiese beheer (kontrole) behels het, vergelyk met deklaagbehandelings in die boomry (deklaag) en behandelings waar kompostee saam met die deklaag toegedien was in die boomry (deklaag + kompostee). Al die behandelings is gekombineer met verkillende tussenry behandelings wat ‘n totaal van agt verskillende behandelings behels het. Hierdie verslag konsentreer slegs op die behandelings in die boomry, waar die kontrole behandelings wat ‘n standaard bememestings program ontvang het, vergelyk word met die deklaag behandelings, wat geen alternatiewe bemesting ontvang het nie en as organise alternatiewe beskou word in ‘n ‘Cripps’ Pink’ appelboord. Klem in die verslag is gelê op die hoof effekte van die behandelings op vrugkwaliteit. Beide die persentasie grondkoolstof en die katioonuitruilkapasiteit het ‘n betekenisvolle toename getoon by al die deklaagbehandelings in vergelyking met die kontrole behandeling. Terselfdetyd, het al die deklaagbehandelings ook verskeie grondminerale betekenisvol verhoog, waarvan slegs P betekenisvol in beide die blare en vrugte verhoog is. Die tempo van grondmikrobe aktiwiteit en micorrhiza-kolonisasie van die wortels is betekenisvol verhoog deur die deklaagbehandelings, maar het gerealiseer in ‘n betekenisvolle laer opbrengseffektiwiteit in vergelyking met die anorganiese, kontrole behandeling. Dit kan onder andere toegeskryf word aan die mikrobe aktiwiteit van die komposdeklaag gedurende die lente – alhoewel dit nie per se in die studie gekwantifiseer is nie, sook die toename in vegetatiewe groeikrag aan die einde van die proeftydperk. Dit is wel indirek gereflekteer deur die betekenisvolle, laer vrug N van die deklaagbehandelings en die laer tempo van mikrobe aktiwiteit gedurende die lente by die deklaagbehandelings op die perseel. Wat die toedienning van kompostee betref, het dit geen betekenisvolle bydra gelewer in terme van gewasprestasie, grondminerale of microbe-aktiwiteit oor ‘n tydperk van sewe jaar in vergelyking met die behandelings waar die deklaag geen kompostee ontvang het nie. In vergelyking met die proef by Lourensford Landgoed, met geen betekenisvolle verskille in vrug mineral-analises tussen die behandelings oor ‘n tydperk van twee jaar nie, het die proef te Elgin wel betekenisvolle verskille tussen behandelings na 6 (2009) en 7 (2010) jaar getoon in geval van P, vir sekere behandelings (4,7,8 versus 1,2,6). Slegs in 2010 het meer behandelings betekenisvolle verskille getoon vir N, Mn, Fe en Zn. Rakende vrugkwaliteit - in ooreenstemming met resultate van 2009 vir perseel 1 te Lourensford Landgoed - het beide seisoene betekenisvolle verskille ten opsigte van appelsuur getoon in Elgin. Die verskille het egter nie konstant in al die behandelings voorgekom nie. Stysel afbraak, totaal oplosbare stowwe en fermheid het ook betekenisvolle verskille tussen behandelings getoon in Elgin – maar dit was nie konsekwent oor behandelings of seisoene nie en het ook nie voorgekom in die Lourensford Landgoed persele nie.

Fruit split is the most important physiological disorder in pomegranate production, causing devastating crop losses worldwide. Foliar nutrient applications have been used experimentally to mitigate pomegranate fruit split but none have been conducted using the industry standard cultivar, Wonderful, and little is known about the effects of foliar nutrient applications on pomegranate. Additionally, investigations into putative health benefits of pomegranate fruit have increased interest in its production but limited evidence exists regarding effects of agricultural practices such as foliar fertilizer applications on internal fruit quality. ‘Wonderful’ pomegranate trees at 2 commercial orchards were treated with foliar applications of ZnSO4 (3000 mg∙L-1, 4000 mg∙L-1, or 5000 mg∙L-1), MgSO4 (1%, 2%, or 3%), KNO3 (1%, 2%, or 3%), or deionized (DI) water (control). Fruit were analyzed for fruit split incidence, yield, fruit number per tree, fruit diameter, fruit mass, mass of all arils in fruit, mass of 100 arils, total soluble solids (TSS), titratable acidity (TA), antioxidant activity (AA), total phenolics (TP), and mineral nutrient concentrations of leaves and fruit. Foliar applications of MgSO4 and ZnSO4 resulted in significantly lower fruit split incidence. Treatments had no significant effect on fruit number per tree, fruit diameter, and mass, mass of all arils in fruit, or mass of 100 arils. Leaf N, K, S, Mn, and Zn were significantly affected by the treatments. TSS and TA were not affected significantly by treatments. AA ranged from 77.8-84.3 percent inhibition of 2,2’-diphenyl-1-picrylhydrazyl and TP ranged from 2489-3046 mg·L-1 gallic acid equivalents, with some KNO3 treatments significantly affecting these parameters. Fruit mineral nutrient concentrations were characterized and Zn-treated trees had greater fruit Zn concentrations. The results suggest that foliar ZnSO4 or MgSO4 could be used to decrease fruit split incidence and increase nutritional content of ‘Wonderful’ pomegranate and any of the three tested foliar nutrients could be applied as a foliar fertilizer without negatively impacting fruit yield, size, internal quality, bioactivity, or mineral nutrient concentration.

Thesis (MScAgric)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Limited research is available on the effect of mulches on established orchards. Most of the information available stems from research conducted in newly planted orchards or on annual crops such as green peppers and strawberries under greenhouse conditions. To increase the current knowledge on the effect of mulches in established orchards, two field trials were conducted on 14 year old „Cripps‟ Pink‟ orchards. The one trial concentrated on the influence of mulches on the root environment and the other trial on the effect of mulches on growth, yield and fruit quality. Both trials were conducted at Lourensford Estate near Somerset West, but the sites differed in soil texture between lighter soil (Tukulu) and heavier soil (Clovelly). Four different mulches were used viz. compost, wood chips, vermi-castings (topped with thin layer of woodchips) and a woven geotextile fabric. These four treatments were compared to an un-mulched control, managed according to industry norms. After reducing irrigation volume in the 2010/2011 season, with a further reduction in the 2011/2012 season, more significant differences were obtained in nutrient levels of fruit and leaves compared to the 2008/2009 and 2009/2010 seasons of the trial. Leaf and fruit nutrients showed significant differences in both sites, but the differences were more pronounced on the lighter soil. At the heavier soil site, the vermi-castings, woodchips and compost treatments increased fruit phosphorus (P) during 2010/2011 and the control treatment increased fruit boron (B) during 2011/2012. Only leaf magnesium (Mg) was increased by woodchips and vermi-castings in 2011/2012 at this site. In the lighter soil site, the control treatment had the highest fruit B levels in 2010/2011 while the vermi-castings and the woodchips treatments had the highest fruit P levels in 2011/2012. For the same site, vermi-casting and compost treatments improved leaf potassium (K) uptake in 2010/2011 and 2011/2012, whereas woodchips and geotextile significantly improved leaf copper (Cu) uptake in 2010/2011 compared to the control. To determine if applied nutrients were trapped in the organic mulches over time, leading to a deficiency in the soil and eventually the tree, a mineral analysis was conducted on the organic mulches at the end of each season. Results of the two seasons indicated that vermi-castings contained higher total nutrient levels than the other two organic mulches, but the difference in nutrient levels were shown not to be directly related to the fertilisers applied during each season. In the case of vermi-castings, nutrient quantities in the original material applied at the beginning of each season were higher than those of the other organic mulches. The higher nutrient levels in organic in comparison to inorganic mulches were however not reflected in the fruit and leaf mineral analysis of these treatments. The overall treatment effect in terms of changes in nutrient levels in the tree became less significant when trees were over irrigated. This became evident as the differences between mulching treatments increased as the irrigation was reduced during the season, indicating the masking effect of irrigation on mulching. Evaluating the effect of mulches on growth, yield and fruit quality showed significant differences only at the heavier soil site. The vermi-casting treatment had significantly higher yield efficiencies than the control for the 2010/2011 season. Compost had the lowest yield efficiency at both sites, also during the previous two seasons that formed part of an earlier study (Kotze 2012). In 2011/2012, the compost treatment also showed significantly higher shoot growth than the control. Compost therefore could increase vegetative growth in established orchards on a heavier soil after application for four seasons. Taking the cost of mulching into account, wood chips are the only treatment that can be recommended without compromising fruit quality. Wood chips will sustain or even improve yield efficiency in an established orchard on especially heavier soil. Future research should study the effect of different amounts of irrigation on the various mulches, as the effect of irrigation was not evaluated in this study.
AFRIKAANSE OPSOMMING: Beperkte navorsing is beskikbaar oor die effek van deklae op bestaande boorde. Die meeste bestaande inligting is gegrond op proewe wat uitgevoer is op nuut aangeplante boorde of op eenjarige gewasse, soos groenrissies en aarbeie, onder kweekhuis toestande. Om bestaande kennis aan te vul rakende die effek van deklae op vrugproduksie en -kwaliteit in bestaande boorde, is twee veldproewe geloots in 14-jaar-oue „Cripps‟ Pink‟ appelboorde. Die een proef het gekonsentreer op die invloed van deklae op die wortel omgewing en die ander proef, op die effek van deklae op groei, opbrengs en vrugkwaliteit. Beide proewe is uitgevoer op Lourensford Landgoed naby Somerset-Wes en twee verskillende grondtipes is hiervoor gebruik: „n ligte grond (Tukulu) en swaarder grond (Clovelly). Vier verskillende deklaagtipes is gebruik naamlik: kompos, houtspaanders, „vermi-castings‟ (bedek met „n dun lagie houtspaanders) en geweefde geotekstiel materiaal. Hierdie vier behandelings is vergelyk met „n onbedekte kontrole wat volgens industrie norm bestuur is. Nadat die besproeiingsvolume verminder is in 2010/2011 en daarna weer in 2011/2012, het meer betekenisvolle verskille tussen behandelings voorgekom in nutriënt-vlakke van vrugte en blare in vergelyking met die eerste twee jaar van die proef (2008/2009 en 2009/2010). Blaar en vrug nutrient-vlakke het betekenisvolle verskille in beide persele getoon, maar die verskille was meer duidelik in die ligte grondtip. In die swaarder grond perseel het die „vermi-castings‟, houtspaanders- en kompos behandelings die vrug fosfaatvlakke (P) betekenisvol verhoog in 2010/2011. In die kontrole behandeling was vrug boorvlakke (B) betekenisvol hoër as die ander behandelings in 2011/2012. In hierdie perseel is net magnesium-vlakke (Mg) in die blare betekenisvol verhoog deur die houtspaanders- en „vermi-castings‟ behandelings in 2011/2012. In die ligte grond perseel het die kontrole behandeling die hoogste vrug B-vlakke in 2010/2011 gehad en die „vermi-castings‟ en houtspaander-behandelings gesamentlik, die hoogste vrug P-vlakke in 2011/2012. Die „vermi-casting‟ en kompos behandelings het kalium-vlakke (K) opname in die blare in 2010/2011 en 2011/2012 verbeter, terwyl die houtspaanders- en geotekstiel behandelings die koper-vlakke (Cu) in die blare in 2010/2011 verbeter het. Om te bepaal of die toediening van voedingstowwe oor tyd kan lei tot die „vashou‟ daarvan in „n organiese deklaag en dan tekorte van sekere nutriënte in die grond en uiteindelik die boom kan veroorsaak, is „n mineral analise van die organiese deklae uitgevoer aan die einde van beide seisoene. Resultate van die twee seisoene het getoon dat „vermi-castings‟ hoër totale nutrient-vlakke gehad het as die ander organiese deklae, maar die nutrient-vlakke was nie direk verwant aan die toegediende voedingstowwe nie. In die geval van „vermi-castings‟, was nutrient-vlakke van die moedermateriaal, wat toegedien is aan die begin van die seisoen, hoër as die van die ander organiese deklae. Hierdie hoër nutrient-vlakke van die organiese teenoor anorganiese behandelings, is nie gereflekteer in hoër nutrient-vlakke in die vrug- en blaar mineraal analises van die bome nie. Behandelings effekte rakende veranderinge in nutrient-vlakke in die boom, nadat die besproeiing verminder is, het verander in vergelyking met die van die vorige twee seisoene en is „n aanduiding van die verbloemende invloed van besproeiing op die prestasie van deklae. Evaluasie van die effek van deklae op groei, opbrengs en vrugkwaliteit het net betekenisvolle verskille in die swaarder grond perseel getoon. Die „vermi-casting‟-behandeling het „n betekenisvolle hoër opbrengseffektiwiteit as die kontrole getoon in 2010/2011. Kompos het die laagste opbrengseffektiwiteit in beide persele gehad en het resultate van die vorige twee seisoene van Kotze (2012) bevestig. Die betekenisvolle hoër lootgroei van kompos as die ander behandelings het net in 2011/2012 voorgekom. Kompos kan dus groei verhoog in „n gevestigde boord, in „n swaarder grond, indien besproeiing optimaal is. In terme van kostes, word die gebruik van houtspaanders as deklaag voorgestel vir „n gevestigde boord met „n swaar slik leem grond, aangesien daar geen nadelige effek op vrugkwaliteit was met die behandeling nie en die opbrengseffektiwiteit van die bome gehandhaaf en selfs verbeter is. Toekomstige navorsing kan die effek van besproeiing op verskillende deklaag tipes bestudeer, aangesien die bestaande proef dit nie kon aanspreek nie.

Wine vineyards in humid environments like the mid-Atlantic United States are characterized by vines that develop too much vegetative growth for optimum quality wine production. Cover crops, rootstocks and rootzone restriction were evaluated for their effect on vegetative and reproductive growth on Cabernet Sauvignon. Treatments were arranged in a strip-split-split plot arrangement with under-trellis cover crops (UTCC) compared to row-middle only cover crop combined with 1-m weed-free strips in the vine row as main plots. Rootstocks riparia Gloire, 420-A, and 101-14 were sub-plots, while sub-sub-plots comprised two treatments: vines were either planted in root-restrictive (RR), fabric bags (0.016 m3) at vineyard establishment (2006), or were planted without root restriction. All three factors were effective in suppressing vegetative development as measured by rate and extent of shoot growth, lateral shoot development, trunk circumference, and dormant pruning weights. Canopies of vines with UTCC and RR had reduced leaf layer values by approximately 21% and 23% compared to conventional controls. The principal effect of the UTCC and the RR treatments was a sustained reduction in stem (xylem) water potential. UTCC and RR caused significant 7 and 10% reductions in berry weight, compared to their conventional controls. Berry weights of vines grafted to riparia were greater than those of vines grafted to other rootstocks. Wine made from UTCC and RR treatments increased red wine color compared to herbicide UTGC and NRR, respectively. This study identified treatments that improve vine balance while simultaneously improving grape composition and potential wine quality.
Master of Science

Influence of tomato (Solanum lycopersicum L.) seedling grafting on the plant growth, fruit yield and quality, and disease tolerance were investigated using 3 cultivars (Big Beef, Celebrity, Cannonball) as scions and two Solanum species (B-blocking, Maxifort) as a rootstock in a randomized complete block design with three replications. The grafted plants were statistically higher in values for stem diameter, leaf chlorophyll, and fruit carotenoid contents. Similarly, the scion/rootstock combination ‘Big Beef/Maxifort’ and ‘Big Beef/B-blocking’ had prolonged days to maturity and gives a higher yield than the non-grafted ‘Big Beef’. Grafting seedling on ‘Maxifort’ and ‘B-blocking’ rootstocks improves the fruit quality like titratable acidity (TA), fruit firmness, but didn’t alter the pH, total soluble solid (TSS), lycopene and TSS/TA. Also, grafted treatment ‘Big Beef/Maxifort’ was found to be a highly disease resistant treatment when compared to the ‘Big Beef’ control with mean relative effect 0.074.

Tomatoes (Lycopersicon esculentum Mill) are one of the most popular vegetable crops grown for fresh market and processing in the U.S. Grafting involves the uniting of a shoot or bud scion with a rootstock to form a compound plant, mainly for managing soil-borne diseases and increasing crop yield. The objectives were to examine the effects of reciprocal and self grafts on tomato fruits, number of fruits, weight, and quality of the cultivars, ‘Cherokee Purple’, ‘Mister Stripey’, ‘Crista’, and ‘Maxifort’. Grafted seedlings were planted at WKU Farm on raised beds, protected with red or black plastic mulch under drip irrigation system with regular supply of water. Matured fruits were harvested, weighed, and number of fruits from each plant recorded. The highest yielding combination was the scion ‘Cherokee purple’ on ‘Maxifort’ rootstock, which produced 304g and 745g heavier fruits than ‘Crista’ and ‘Mister Stripey’, respectively. The quality grade of ‘Crista’ was superior to ‘Cherokee Purple’ and ‘Mister Stripey’ while ‘Mister Stripey’ produced the greatest number of fruits but were of lower quality. Fruits from plants grown on red plastic mulch were significantly larger, heavier, and were of higher quality than those grown on black plastic mulch. However, plants grown on black plastic mulch produced significantly more fruits per plant. There was little advantage for self-grafting of ‘Cherokee Purple’ and ‘Crista’. However, ‘Mister Stripey’ was responsive to self-grafting and merits further investigation. The best rootstock was ‘Maxifort’ which produced the biggest, heaviest fruits of the best quality. ‘Cherokee Purple’ as a scion produced the largest and heaviest fruits, while ‘Crista’ produced the highest quality fruits. ‘Mister Stripey’ was the most prolific in terms of number of fruits per plant.

Mestrado em Engenharia Alimentar - Qualidade e Segurança Alimentar - Instituto Superior de Agronomia
The present study had as main goal the characterization of Adansonia digitata L .fruit, focusing on three specific aspects: physical and chemical description of the fruit pulp, extraction studies and development of drinks based on baobab pulp. The pulp characterization, showed low values for water activity and humidity, high content in essential minerals and a low pH. The pulp was also characterized regarding the total phenolic compounds, vitamin C and antioxidant activity. The results showed high values of total phenols in aqueous solutions, 512 and 603 mg EAG/100mg at room temperature and at 37ºC respectively, an antioxidant activity of 44,36umolTE/g at room temperature and 49,48umolTE/g to 37ºC, determined by the DPPH method and values of vitamin C of 73mg/100 at 37ºC and 125mg/100g at room temperature. In the extraction studies, the relation between solvent/solute was tested as well the influence of temperature during the extractions (room temperature and 37ºC). In this studies we were able to define the relation 3:1 (solvent/solute) and the temperature of 37ºC as the results with better yields. The last part of this work, was the developing of two drinks based on baobab and banana pulp. With this work we were able to conclude that, baobab pulp presents a good nutritional value and the lyophilization process didn’t changed the proprieties of the analyzed fruit

Mestrado Vinifera EuroMaster - Instituto Superior de Agronomia
A study to compare the effects of hedging and curling the shoot tips (rolling) on the last wire of the trellising system was carried out in Saint Emilion (France) on Merlot grapevines in 2011. Vines were hedged or curled when shoots were 30 – 40 cm longer than the highest wire. The effects of the two canopy management strategies on vine performance, mainly vegetative growth, disease occurrence, phenology, water status, yield components and berry composition were compared. Curled, not hedged vines presented longer main shoots, more lateral shoots and higher potassium values on the petioles. Hedged plants had a higher percentage of shaded clusters and a higher leaf layer number at the cluster zone and ¾ of the canopy. Regarding leaf area, curled plants presented a bigger main leaf area but for lateral leaf area no differences were found. Although berries on hedged plants were prone to have a higher mass, no differences for berry composition were found. Hedging seems to be an appropriated technique for the Sain Emilion region as it is less time consuming, less expensive, possible to be mechanized and it has no detriment regarding quality of berries

Effects of trellising on water use, absorption of photosynthetically active radiation (PAR, 400 to 700 nm wavelength) by foliage and potentially by fruit, fruit composition, and yield were studied in 1988 under semi-arid conditions on field-grown Vitis vinifera L. 'Petite Sirah' grapevines in a mature vineyard. The positioning of shoots on trellises resulted in canopies that were (1) positioned vertically (vertical canopy), (2) positioned in a "V" pattern with sides inclined 60° from horizontal (inclined canopy), and (3) inclined toward the vineyard floor (standard canopy). Seasonal water use values determined from neutron scattering data were 393 ± 61, 554 ± 73, and 455 ± 57 mm for the standard, vertical and inclined canopies, respectively. On average, about 50% of seasonal water consumption occurred between fruit set and filling stages for each type of canopy. Average crop factors (ratio of actual to reference crop evapotranspiration) of 0.383, 0.540 and 0.444 were for the period bud burst to harvest for standard, vertical and inclined canopy systems, respectively. The diurnal water use patterns of the three trellising canopies were very similar when measured by either the heat pulse technique or by porometer. The average daily heat pulse velocity (HPV) for selected vertical, inclined and standard canopies for 6 days were 8.77, 7.58 and 6.85 cm h⁻¹, respectively. The HPV technique indicated that the average daily water use of the whole plant was 0.227, 0.192 and 0.137 kg/m² leaf area/d for standard, vertical and inclined canopies, respectively. The daily average transpiration rates as measured by the HPV technique were 32, 31, and 25% higher than the average transpiration rates estimated from porometer data for standard, vertical and inclined canopies, respectively. Stomatal conductances of the vertical and inclined canopies were 20 and 40%, respectively, below that of standard canopy. PAR absorption by foliage during mid-day was highest in the standard trellis, and lowest in the inclined trellis. PAR potentially available for absorption by fruits was lowest in the standard trellis, and highest in the inclined trellis. In both inclined and vertical canopies, the average sunfleck values were 26%, but was only 2% in the standard canopy. Analysis of fruit composition at harvest revealed that total dissolved solids (°Brix) was significantly higher in the inclined trellis than for the vertical trellis or the standard trellis. The inclined trellis resulted in the highest alcohol content of wine. Per vine yields did not differ significantly among the three trellis systems. Overall, the standard trellis was optimum because grapevines consumed less water and produced a shading which protected the fruit from direct solar radiation.

Verticillium wilt is a widespread soilborne disease of strawberry historically controlled by soil fumigation with methyl bromide (MB). MB was banned by the United Nations in 1995 and will be completely phased out by 2015. Research has concentrated on alternative methods of disease control without finding a single alternative able to replace MB in widespread disease control and yield increase. For the current study, strawberries were greenhouse grown in container pots filled with soil from both infested and non-infested areas of a commercial strawberry field in Watsonville, CA. Treatments included pre-plant soil fumigation with commercially available formulations of methyl bromide, chloropicrin, and 1, 3-Dichloropropene. Additional treatments included ozone gas (six treatments) and biological control (three treatments). Collected data included total plant yield, individual berry weight, number of fruit produced per plant, plant vegetative weight, infection status, and mineral concentration of fruit (calcium, magnesium, potassium, iron, zinc, manganese, carbon, and nitrogen). Plants grown in ‘clean’ soil were less likely than plants grown in ‘infested’ soil to be infected with Verticillium. Plants grown in soil treated with MB had higher plant weight and yield than did non-treated control. Ozone and biological control treatments did not have statistically higher yield than non-treated control plants nor statistically lower yield than plants grown in soil treated with MB. Individual berry weights had a narrow range while the number of berries produced per treatment had a wide range. Data suggests strawberry yield is dependent on the number of berries produced per plant. Plants with high vegetative weight produced the highest yield suggesting large plants produce many berries resulting in higher yield.

Since 2011, California has been under drought conditions. These conditions have not only affected water availability for farmers, but also production. California’s second most valuable crop, almonds, has been affected by drought conditions. This study used three models (Model 1-3) to describe almond yield variability from year to year and almond yield variability within a year in Kern County, CA. The study evaluated 185 almond farms that were classified in three locations (east side, west side and north west side). The years of the study were 2011 (wet year) and 2013-2015 (drought condition years). Model 1 determined a functional regression between almond yield and annual evapotranspiration during the 4 years of the study. The R2was 7.9%, meaning low association between both variables and high unexplained variability (92.1%). Model 2 evaluated year to year variation. A regression function between almond yield and annual evapotranspiration after adjusting for location, precipitation, chilling hours and year was made. The R2of this model 62.6%, and all the variables used had a p2was higher than Model 1; however, there was high unexplained variability (47.4%). Model 3 evaluated within-year variation. A regression function between almond yield and annual evapotranspiration after adjusting for tree age and location (east, west and northwest side) was made for each year (2011 and 2013 -2015). Coefficient of variation of evapotranspiration and soil available water storage were analyzed as additional variables in Model 3; however, they were not introduced in Model 3 due to the low increase in R2 in each year (2 of Model 3 for each year were, 60.4%, 49.7%, 53.8% and 53.2% for the years 2011, 2013-2015, respectively. Model 3 also had high unexplained almond yield variability in each year (39.6%-50.3%). This high unexplained variability leads to introduce additional variables to the functional regression model for further studies. Identifying these additional variables and having a functional regression model with high R2 would lead to understand howlow evapotranspiration could potentially lead to a positive response on yield in drought conditions; thus, making farmers improve water use efficiency and hence, lowering production cost. However, the high unexplained variability clearly indicates that evapotranspiration is only one of many factors that influence yield. If improved yield is an important outcome, future studies must examine large- scale almond-producing farms with multiple agricultural system variables.

This study consisted of field experiments to determine the effect of sodium catchment on the distribution of soluble salts and exchangeable ions in soil, leaf ion concentration, and yield of peaches. The experiments were conducted at the Oracle Agricultural Center, formerly known as Page Ranch, University of Arizona, for a period of two years. The soil in this area is White House sandy clay loam. Sodium chloride salt was applied at a rate of 11.2 ton/ha to the Sodium Treated Catchment Area (STCA). Also, sulfur was applied at a rate of.5 kg m⁻² to Cropped Water Ways (CWW). Four peach cultivars planted in single rows with 2, 3 and 4 meter spacing in one cropped waterway, were selected for this study. Soil samples were collected at 20 cm intervals to a total depth of 160 cm. Twelve sites were selected in the CWW, three sites were selected in the STCA and one site chosen Outside Water Harvesting System (OWS). Also, 12 soil samples were collected from the three sites at different depths in CWW. Soil samples were then analyzed for pH, EC, C²⁺, Mg²⁺, Na⁺, K⁺, Cl⁻ and SO₄⁻². Four runoff samples were collected at CWW and their EC, Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl⁻, SO₄⁻², and HCO₃⁻ contents were analyzed. Twelve peach leaf samples, one sample from each replicate, were collected and analyzed for Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl⁻ and SO₄⁻². A computer model was developed to predict the actual fruit yield. The results of these experiments showed that no salinity problems have occurred in CWW, a good water quality resulted from sodium catchment and ten years after sodium was added to the soil, 65% of it still remains in the upper profile of STCA. Soil cation distribution was approximately the same at different depths for K⁺ and Mg²⁺, but had a different distribution pattern for Na⁺ and Ca²⁺ in the CWW. A significant correlation was found between soil depth, and pH, EC, and SAR. There was not significant difference in leaf uptake of Ca²⁺, SO₄⁻², Na⁺, and Cl⁻ using the same variety of peach with different spacing or different varieties with the same spacing. The results also showed that the interaction between variety and spacing did not significantly affect the yield in 1988, and significantly affected the yield in 1989.

The mango tree is one the important sources of income in the rural economy of Senegal. However, mango producers in Ziguinchor are facing fruit fly infestations leading to important losses in income. The aim of this study is to measure the impact of the losses encountered by mango farmers in Ziguinchor over three years 2012, 2013, and 2014 and conduct an econometric study to examine household characteristics associated with high level of losses. At the household level, the total yearly losses on average from fruit fly infestations represent 17.09 % of the average total household income in Ziguinchor (Casamance). The losses associated with variability of production are much smaller than losses from decreases of average yield. Furthermore, the results show that the number of hectares, level production, and use of Keitt varieties are three factors statistically significant, with a significant positive influence on losses from infestation. The use of fruit fly control technologies does not appear to significantly reduce losses.
Master of Science

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O meloeiro tem se destacado no Nordeste em razão das condições de solo e clima que favorecerem o cultivo dessa olerícola. É uma planta da família das cucurbitáceas que permite várias formas de manipulação da relação entre a fonte e o dreno por meio de seu manejo cultural. Uma possibilidade de alterar a relação fonte:dreno no meloeiro seria a utilização do agrotêxtil (tecido não tecido) em diferentes épocas, associada com a fixação de diferente número de frutos por planta. O trabalho teve como objetivo avaliar a partição de assimilados, a produtividade e a qualidade de frutos do meloeiro quando submetidos à retirada do agrotêxtil em diferentes épocas e fixação de fruto na planta. O experimento foi realizado no Centro de Ciências e Tecnologia Agroalimentar (CCTA/UFCG) durante o período de agosto a dezembro de 2014, com plantas do híbrido de melão Cantaloupe Hopey King, no espaçamento de 2,0 x 0,8 m em Pombal - PB. O delineamento experimental foi o de blocos casualizados com os tratamentos alocados em um arranjo em parcelas subdivididas (5x3), onde na parcela constaram de diferentes épocas de retirada do agrotêxtil (20, 24, 28, 32, e 36 dias após o transplante), e na sub parcela de diferentes fixações de frutos na planta (1 fruto, 2 frutos e fixação livre) em oito repetições, sendo quatro utilizadas para as avaliações de crescimento e quatro para a produção e qualidade dos frutos. Avaliou-se neste trabalho a quantificação da expressão do sexo, o crescimento e a partição de assimilados, a produção e a qualidade dos frutos. A retirada do agrotêxtil em diferentes épocas e o número de frutos por plantas afetaram significativamente a relação fonte:dreno. As épocas de retirada do agrotêxtil e a fixação fruto promoveram alterações no crescimento, produção e qualidade dos frutos do meloeiro. O atraso na retirada do agrotêxtil de 20,0 para 36,0 DAT proporcionaram maiores número de flores hermafroditas, massa seca da folha e da parte aérea, área foliar e redução nos sólidos solúveis totais. A frutificação livre na planta reduziu o número de flores hermafroditas e elevou a massa seca do fruto e índice de colheita. A massa do fruto e a produtividade da cultura atingiu o máximo valor com a retirada do agrotêxtil aos 26,6 e 25,1 DAT, respectivamente. Plantas com um e dois frutos apresentaram maior massa, porém com menor produtividade, se comparado a plantas com fixação livre de frutos. A utilização do agrotêxtil a partir dos 25 DAT dificultou as práticas culturais como capinas e penteamneto das plantas devido ao entrelaçamento de ramas dentro do túnel ocasionando maior queda de flores e reduzindo a produtividade da cultura.
The melon has excelled in the Northeast because of soil and climate conditions that favor the cultivation of this vegetable crop. It is a plant of the Cucurbitaceae family which allows various forms of manipulation of the relationship between the source and the drain by means of their cultural practices. A possibility to change the font ratio: drain the melon would be the use of the agrotextile (nonwoven fabric) at different times associated with fixing different number of fruits per plant. The study aimed to assess the assimilated partition, productivity and the quality of the melon fruit when subjected to removal of the nonwoven at different times and setting fruit in the plant. The experiment was conducted in the Science Center and Agrifood Technology (CCTA / UFCG) during the period from August to December 2014, with melon hybrid plants Cantaloupe Hopey King in the spacing of 2.0 x 0.8 m in Pombal - PB. The experimental design was a randomized block with treatments assigned to a split plot arrangement (5x3), which consisted in part of different periods of withdrawal of the row cover (20, 24, 28, 32, and 36 days after transplantation) and sub plot of different fruits fixings in the plant (1 fruit, 2 fruit and free) in eight repetitions, four used for the growth of reviews and four for the production and fruit quality. It was evaluated in this study to quantify the expression of sex, growth and assimilated partition, production and fruit quality. The withdrawal of agrotextile at different times and the number of fruits per plant significantly affected the supply relationship: drain. The withdrawal times of the nonwoven and fruit fixation promoted alterations in the growth, production and fruit quality of melon. The delay in the withdrawal of agrotextile 20.0 to 36.0 DAT provided higher number of hermaphrodite flowers, dry weight of leaf and shoot, leaf area and reduction in soluble solids. Free fruiting in the plant reduced the number of hermaphrodite flowers and raised the dry matter of the fruit and harvest index. The fruit mass and crop yield peaked with the removal of agrotextile to 26.6 and 25.1 DAT, respectively. Plants with one and two fruits presented greater mass but with lower productivity compared to plants with fruits of free determination. The use of nonwoven from 25 DAT difficult cultural practices as weeding and combing plants due to the intertwining branches into the tunnel leading to higher drop flowers and reducing crop yield

The importance of European honey bees in improving fruit set, yield and fruit weight of kiwifruit on the central east coast of Australia was investigated. Field investigations were carried out using different bee saturations and different types of male pollen parents. These investigations confirmed the importance of honey bees in kiwifruit fruit set, yield and fruit weight. However, the results suggested that increasing bee activity alone may not increase pollination of kiwifruit by honey bees. Many factors need to be understood before introducing bees into the orchard. Bees were more effective during the early part of the flowering period, and bee activity varied according to the sex of the vine, planting design and the time of day. The type of male pollen parents also influenced fruit size and quality. Flowers pollinated by different pollen parents were assessed for pollen tube growth and histochemical changes. The resulting fruit were also examined for weight and seed numbers. Honey bees play the major role in the size and yield of kiwifruit, but the design of male vines, their age and type of male pollen may also contribute. The kiwifruit pistil also possesses important features that can be considered as adaptations to insect pollination.

El presseguer és un fruiter important a la regió fructícola de Lleida (nord-est d'Espanya), amb un augment progressiu durant els darrers anys. Les tendències actuals van cap a plantacions d'alta densitat, noves varietats i sistemes de reg per goteig. Els productors de presseguer estan interessats en gestionar el reg i la fertilització nitrogenada, per què afecten el creixement de l'arbre i poden ajudar a millorar els resultats de collita i qualitat de la fruita. Es va establir un experiment de camp de tres anys (2006-2008) en presseguer cv. Andross en una plantació comercial amb recol·lecció mecànica per a la indústria del processat. Els arbres estaven formats en un sistema de palmeta lliure i sense aclarir la càrrega de fruits. Els arbres es van recol·lectar mecànicament amb un vibrador de tronc continu. El sòl era de textura franca, ben drenat, amb una baixa capacitat de retenció d'aigua (30% en volum d'elements grossos i un horitzó petrocàlcic a 45 cm de profunditat). Es van avaluar tres estratègies de reg d'acord amb les fases de creixement del fruit: reg complet durant tota la temporada de cultiu (FI), restricció del reg durant la fase-II (IR2, 70% de restricció) i restricció del reg durant la fase-III (IR3, 30% de restricció), combinat amb tres tractaments de fertilització nitrogenada: 0, 60 i 120 kg N ha-1 any-1. Els arbres es van fertigar diàriament. El disseny experimental va ser en blocs complets a l'atzar amb quatre repeticions. Es va mesurar el creixement estacional del fruit, el contingut d'aigua del sòl, la contracció del tronc, l'estat hídric dels arbres i la nutrició mineral. A la recol·lecció es van determinar els components de la producció i a repòs hivernal el pes de la poda. Els resultats mostren que els canvis diaris en contingut d'aigua del sòl, mesurat amb sondes de capacitància, es poden relacionar amb el dèficit d'aigua en cada fase de desenvolupament, i que el balanç d'aigua pot explicar el curs de la contracció del tronc, mesurat amb dendrómetros. La restricció del reg va afectar el contingut d'aigua del sòl i el potencial hídric de tija al migdia. Durant la fase-III, es va establir un nivell llindar de 0,167 m3 m-3 en contingut d'aigua del sòl per a la disminució del potencial hídric de tija al migdia. La conductància estomàtica al migdia va augmentar al llarg del període de creixement del fruit. En tots els anys, el tractament IR2 va reduir la concentració de K foliar, mentre que va passar el contrari en la concentració en fulla de Ca i Mg. També IR2 va augmentar el pes específic de la fulla i va reduir el pes de la poda. Aquests efectes es van mantenir tot i que el reg complet va ser restablert durant la fase-III. Al contrari, l'estratègia IR3 no va afectar les relacions nutritives ni el pes de la poda. L'aplicació de N va suposar un augment de la concentració de N en fulles, fruits i brots a l'hivern, des del primer any experimental. L'increment de la dosi de N va produir una disminució de la concentració de K en fulla, però va augmentar la concentració de S en fulla. En arbres amb FI, l'aplicació de N va suposar un augment de la càrrega de fruits, de la mida de la copa i de la collita. També l'aplicació de N va augmentar l'índex de productivitat de l'aigua. La collita total va ser menor el 2006 que el 2007 i 2008, a causa de canvis en la càrrega de fruits dels arbres. El 2007, però, l'efecte del reg durant la fase-III va dependre de l'aplicació de N, i es va observar un efecte positiu sobre la collita amb l'increment de N en arbres amb FI, mentre que va passar el contrari en els arbres amb IR3. Així, la collita menor es va obtenir amb IR3 combinat amb N120. Amb IR2, la collita va ser independent de l'aplicació de N. El 2008, amb un major contingut d'aigua del sòl, no hi va haver efecte d'interacció, i l'aplicació de N va augmentar la collita en tots els tractaments de reg. L'aplicació amb IR2 durant l'enduriment de l'os va permetre augmentar l'índex de productivitat de l'aigua i millorar la maduració dels fruits. D'altra banda, IR3 va reduir la mida del fruit i va augmentar sòlids solubles totals a collita. Amb tots els tractaments es va obtenir una correlació positiva entre el percentatge de matèria seca del fruit i els sòlids solubles totals. Tot i que l'aplicació més elevada de N va retardar la maduració dels fruits, no hi va haver una interacció significativa entre el reg i l'aplicació de N. En general, l'aplicació de 120 kg N ha-1 any-1 proporciona una dosi màxima de N en les condicions d'aquesta plantació, que podrà ser reduïda sota restricció de reg.
El melocotonero es un frutal importante en la región de Lleida (noreste de España), con un aumento progresivo en los últimos años. Las tendencias actuales van hacia plantaciones de alta densidad, nuevas variedades y sistemas de riego por goteo. Los productores de melocotonero están interesados en gestionar el riego y la fertilización nitrogenada, por que afectan el crecimiento del árbol y pueden ayudar a mejorar los resultados de cosecha y calidad de la fruta. Se estableció un experimento en campo de tres años (2006-2008) en melocotonero cv. Andross en una plantación comercial con recolección mecánica para la industria del procesado. Los árboles estaban formados en un sistema de palmeta libre y sin aclarar la carga de frutos. Los árboles fueron cosechados mecánicamente con un vibrador de tronco continuo. El tipo de suelo era de textura franca, bien drenados, con una baja capacidad de retención de agua (30% en volumen de elementos gruesos y un horizonte petrocálcico a 45 cm de profundidad). Se evaluaron tres estrategias de riego de acuerdo con las fases de crecimiento del fruto: riego completo durante toda la temporada de cultivo (FI), restricción del riego durante la fase-II (IR2, 70% de restricción) y restricción del riego durante la fase-III (IR3, 30% de restricción), combinado con tres tratamientos de fertilización nitrogenada: 0, 60 y 120 kg N ha-1 año-1. Los árboles se fertigaban diariamente. El diseño experimental fue en bloques completos al azar con cuatro repeticiones. Se midió el crecimiento estacional del fruto, el contenido de agua del suelo, la contracción del tronco, el estado hídrico de los árboles y la nutrición mineral. A cosecha se determinaron los componentes de la producción y en reposo invernal el peso de la poda. Los resultados mostraron que los cambios diarios en contenido de agua del suelo, medidos con sondas de capacitancia, se pueden relacionar con el déficit de agua en cada fase de desarrollo, y que el balance de agua puede explicar el curso de la contracción del tronco, medidos con dendrómetros. La restricción del riego afectó el contenido de agua del suelo y el potencial hídrico de tallo al mediodía. Durante la fase-III, se estableció un nivel umbral de 0,167 m3 m-3 en contenido de agua del suelo para la disminución del potencial hídrico de tallo al mediodía. La conductancia estomática al mediodía aumentó a lo largo del período de crecimiento del fruto. En todos los años, el tratamiento IR2 redujo la concentración de K foliar, mientras que ocurrió lo contrario en la concentración en hoja de Ca y Mg. También IR2 aumentó el peso específico de la hoja y redujo el peso de la poda. Estos efectos se mantuvieron a pesar de que el riego completo fue restaurado durante la fase-III. Al contrario, la estrategia IR3 no afectó las relaciones nutritivas ni el peso de la poda. La aplicación de N supuso un aumento de la concentración de N en hojas, frutos y brotes en invierno, desde el primer año experimental. El incremento de la dosis de N produjo una disminución de la concentración de K en hoja, pero aumentó la concentración en hoja de S. En árboles con FI, la aplicación de N supuso un aumento de la carga de frutos, del tamaño de la copa y de la cosecha. También la aplicación de N aumentó el índice de productividad del agua. El rendimiento total fue menor en 2006 que en 2007 y 2008, debido a cambios en la carga de frutos de los árboles. En 2007, sin embargo, el efecto del riego durante la fase-III dependió de la aplicación de N, y se observó un efecto positivo de la cosecha con en incremento de N en árboles con FI, mientras que ocurrió lo contrario en los árboles con IR3. Así, la cosecha menor se obtuvo con IR3 combinado con N120. Con IR2, la cosecha fue independiente de la aplicación de N. En 2008, con un mayor contenido de agua del suelo, no hubo efecto de interacción, y la aplicación de N aumentó el rendimiento en todos los tratamientos de riego. La aplicación con IR2 durante el endurecimiento del hueso permitió aumentar el índice de productividad del agua y mejorar la maduración de los frutos. Por otra parte, IR3 redujo el tamaño del fruto y el aumentó de los sólidos solubles totales a cosecha. Con todos los tratamientos se obtuvo una correlación positiva entre el porcentaje de materia seca del fruto y los sólidos solubles totales. Aunque la aplicación más elevada de N retrasó la maduración de los frutos, no hubo una interacción significativa entre el riego y la aplicación de N. En general, la aplicación de 120 kg N ha-1 año-1 proporciona una dosis máxima de N en las condiciones de esta plantación, que podrá ser reducida bajo restricción de riego.
Peach is an important fruit tree in the horticultural region of Lleida (Northeast of Spain), with a progressive increase in the last years. Recent trends in peach orchards have been towards high density plantings, new cultivars and drip irrigation systems. Peach producers are interested to manage irrigation and nitrogen fertilization, that affect tree growth and may help to achieve good results in yield and fruit quality. A three year field experiment (2006-2008) on peach cv. Andross was conducted in a commercial orchard for the processing industry. Trees were unthinned and trained on a free palmeta. Trees were mechanically harvested with a continuum trunk shaker. The soil type was loam textured, well drained, with a low water holding capacity (30% volume of coarse elements and a petrocalcic horizon at 45 cm depth). Three irrigation treatments were evaluated according to fruit growth stages: full irrigation during all the growing season (FI), irrigation restriction during stage-II (IR2, 70% restriction) and irrigation restriction during stage-III (IR3, 30% restriction), combined with three nitrogen fertilization treatments: 0, 60 and 120 kg N ha-1 year-1 Trees were daily fertigated. The experimental design was randomised complete block with four repetitions. Seasonal fruit growth, soil water content, trunk shrinkage, tree water status and mineral nutrition were monitored. Yield components were determined at harvest and pruning weight was determined at tree rest. Results show that daily changes of soil water content, measured with capacitance probes, could be correlated to water deficit for each development stage, and that water balance can explain the daily course of trunk shrinkage, measured with dendrometers. Irrigation restriction affected soil water content and midday stem water potential. For stage-III, a threshold level for the onset of midday stem water potential decline was established at 0.167 m3 m-3 of soil water content. Midday stomatal conductance increased along the fruit growth period. During all years, IR2 reduced leaf K concentration, while the opposite occurred with leaf Ca and Mg concentration. Also IR2 increased the specific leaf weight and reduced the pruning weight. These effects were maintained although complete irrigation was restored during the stage-III. In contrast, IR3 did not affect nutrient relations or pruning weight. N application supposed an increase in N concentration in leaves, fruits and dormant shoots, from the first experimental year. Increasing N application produced a decrease in leaf K, but an increase in leaf S. In FI trees, N application supposed an increase in fruit load, canopy size and yield. Also N application increased the water productivity. Total yield was lower in 2006 than in 2007 and 2008, due to changes in fruit load. Nevertheless, in 2007 the effect of irrigation during stage-III was dependent on N application, and a positive yield effect of N dose in FI trees was observed, while the opposite occurred in IR3 trees. Thus the lowest yield was obtained in the IR3 combined with N120. Under IR2, yield was independent of N application. In 2008, with higher soil water content, there was no interaction effect, and N application increased yield within all irrigation treatments. The application of IR2 during pit hardening allowed to increase the water productivity and enhance fruit ripening. On the other hand, IR3 reduced the fruit size and increased the total soluble solids at harvest. Among all treatments, the percentage of fruit dry matter was positively correlated with the total soluble solids. Although the highest N application delayed fruit ripening, there were no significant interaction between irrigation and N application. As an overall, in FI trees, the application of 120 kg N ha-1 year-1 provides a maximum N dose in such orchard conditions, which may be reduced under irrigation restriction.

In the Mediterranean area water is a scarce natural resource and periods of drought are frequent. It is then important to increase water use efficiency of irrigated crops. In order to achieve this, one promising option is regulated deficit irrigation (RDI). RDI consists in reducing water application during stages of crop development when yield and fruit quality have low sensitivity to water stress. Full irrigation is provided during the rest of the season to maintain production and fruit quality at adequate levels (Behboudian and Mills, 1997). In citrus, flowering and fruit set are sensitive periods to water restrictions, because water stress during this period increases fruit drop (Ginestar and Castel 1996). The more appropriate phenological period for applying water restrictions seems to be the summer period providing that water applications returned at full dosage sufficiently before harvest in order to allow for compensation in fruit growth (Cohen and Goell 1988). Previous work by González-Altozano and Castel (1999) showed the feasibility of applying RDI in 'Clementina de Nules' and identified threshold values of plant water stress that allowed water savings of about 10-20% without any detrimental effect on yield or fruit size. It would be desirable now to study the extrapolation of these results to commercial orchards of citrus and assess the use of RDI in different citrus cultivars. Two RDI strategies (RDI-1, irrigated at 50% of crop evapotranspiration (ETc) during summer and; RDI-2, irrigated at 35% ETc during the same period to RDI-1) will be compared with a control treatment irrigated at full requirements. As the level of water stress reached by trees is the important factor when RDI strategies are applied, the study of accurate water stress indicators for citrus is also needed. Thus, during the period of water restrictions the use of sap flow and canopy temperature measurements, obtained by thermal imaging or by means of fixed infrared thermometer sensors, will be assessed and compared to classical methods like stem water potential and stomatal conductance.
Ballester Lurbe, C. (2013). Regulated deficit irrigation in citrus: agronomic response and water stress indicators [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/28582
TESIS
Premiado

Abstract Plant Growth Regulator Sprays and Girdling: Potential Horticultural Techniques to Increase Fruit Retention and Yield of Longan (Dimocarpus longan Lour.) Trees in California Leila Graves June 2009 The longan is a subtropical fruit tree whose popularity is growing quickly among American consumers, and thus, could become a lucrative niche market for California growers. Trees planted as part of an initial variety trial conducted in commercial California orchards are beginning to bear fruit. However, fruit retention and yields are low due to excessive abscission during early fruit set. Horticultural techniques, such as plant growth regulator (PGR) sprays and girdling, often increase fruit retention and yield of fruit tree crops, though effects are typically dependent on treatment timing and PGR concentration. The objective of this study was to identify PGR and girdling techniques that result in increased longan fruit retention. The experiment was conducted in a commercial orchard using a randomized complete block design with whole-tree experimental units and five replications per treatment. Treatments included foliar applications of two synthetic auxins, 1-naphthaleneacetic acid (NAA) at 20, 60, or 100 ppm or 2,4-dichlorophenoxyacetic acid (2,4-D) at 5, 25, or 45 ppm, each applied during early or late fruit set. Girdling was also conducted at early or late fruit set, for a total of 15 treatments, including an untreated control. Factors examined at harvest included fruit number and mass per inflorescence and individual fruit mass and diameter. During the on-crop year, a significant increase in the number and mass of fruit per inflorescence was observed in response to 25 ppm 2,4-D applied at late fruit set, as compared to the control. Despite this increase in fruit number, 25 ppm 2,4-D applied at late fruit set did not result in decreased diameter and mass of individual fruit. Late fruit set applications of 25 ppm 2,4-D appear to mitigate the effects of alternate bearing in the off-crop year. Fruit abscission during early and/or late fruit set decreased in response to 5 ppm 2,4-D at early fruit set, 25 or 45 ppm 2,4-D at early or late fruit set, or 100 ppm NAA at early fruit set. Fruit loss occurred as a result of Santa Ana winds during both growing seasons. Neither leaf nor fruit nutrient concentrations of treated trees were significantly different from that of untreated controls. Results indicate that properly-timed PGR applications have the potential to be used commercially to increase yield and profit to longan growers in California.

Les composés aromatiques sont des métabolites secondaires qui jouent un rôle clé dans la qualité du raisin. Les terpènes, les C-13 norisoprénoïdes, les phénols et les alcools non terpéniques sont les composés aromatiques les plus importants dans les raisins et peuvent être accumulés sous forme de molécules libres volatiles ou glyco-conjugués. Le groupe des précurseurs aromatiques glycosylés (GAP) est le plus important et il est présent dans toutes les variétés de Vitis vinifera (L.), l'espèce la plus largement utilisée pour la production de vin. Les GAP représentent 80 à 90% du potentiel aromatique du raisin selon le cultivar. Les pratiques agronomiques telles que l'irrigation, les systèmes de formation, l'effeuillage et l'éclaircissage des régimes peuvent avoir un impact sur le développement de la plante et des fruits. La modification de la relation source/puits (S/P) dans le but d'augmenter la qualité des raisins et une pratique très courante en viticulture. Ces pratiques comprennent l'éclaircissage, l'écimage et le contrôle du nombre de bourgeons par plante. L'éclaircissage, est une pratique très rependue en viticulture et ayant un impact direct sur le rapport S/P, alors qu'il n’y a pas beaucoup de travaux sur l’effet réel de l’éclaircissage sur l'accumulation des GAP. Dans de nombreux cas, les cahiers des charges des AOP et d'IGP prévoient une limite du rendement en fruits par hectare. Ensuite, les viticulteurs régulent les rendements en gérant le nombre de bourgeons/hectare et/ou en éclaircissant les fruits.L'objectif principal de nos travaux etait d'analyser l'impact des modifications du rapport S/P sur la biosynthèse des GAP. Les GAP ont été choisis car : i) ils sont présents dans tous les cultivars de Vitis vinifera, ii) ils représentent la plus grande source de molécules aromatiques potentielles et iii) car ces molécules incorporant des groupes glycosylés, leur accumulation dépend de la fourniture en hydrates de carbone donc potentiellement de la balance carbonée de la plante.L'objectif principal de nos travaux a concerné l'étude de l'impact du rapport source/puits sur la biosynthèse des GAP, et sa modulation éventuelle en fonction du génotype. Cinq questions ont été abordées : 1) L'influence du génotype sur la biosynthèse des GAP et son accumulation à un stade de maturité donné. 2) L'influence de l’année sur la croissance du raisin et l'accumulation des GAP. 3) L'impact de l'équilibre S/P sur la biosynthèse des GAP exprimé en concentration (µg/L) et en quantité (µg/baie) en fonction du développement du raisin. 4) La relation entre les métabolismes primaire et secondaire (GAP et anthocyanes) et leur modulation en fonction de l'équilibre S/P. 5) Influence de la date d'éclaircissage sur la dynamique de biosynthèse des GAP.Les résultats ont montré que les teneurs en composés aromatiques glycosylés variaient en fonction du génotype. Les variétés dont les raisins contiennent des composés terpéniques (Muscat à petits grains blancs et l'hybride V. vinifera x Muscadinia rotundifolia G5) ont présenté les plus grandes teneurs en GAP aussi bien en concentration qu'en quantité par fruit. Ces mêmes génotypes ont montré les valeurs les plus élevées du rapport GAP/sucre. En général, les génotypes produisant des baies non colorées ont présenté des ratios GAP/sucre plus élevés que les variétés à baies colorées
Aroma compounds are secondary metabolites that play a key role in grape quality. Terpenes, C13-norisoprenoids, phenols and non-terpenic alcohols are the most important aroma compounds in grapes and can be accumulated as free volatile or glycoconjugated molecules. The non-volatile glycosylated aroma precursors (GAP) group is the largest one, and it is present in all varieties of Vitis vinifera (L.), the most widely-used species for wine production. Agronomic practices such as irrigation, training systems, leaf removal and bunch thinning can impact the plant and fruit development. The modification of the source/sink relationship (S/S) with the scope of increasing the grape quality, is very common between viticulturists. These practices include bunch thinning, pruning, and the election of the number of buds/plant. Bunch thinning, a very extended practice in viticulture and which directly impacts on S/S, is one of the less researched practice regarding GAP. In many cases, DOC and IGT production protocols include a limit in the fruit yield per hectare. Then, viticulturists regulate yield by managing number of buds/hectare and/or by fruit thinning.The main objective of our work was to analyze the impact of the modifications of S/S balance on the biosynthesis of GAP. GAP are chosen in this research because: 1) they are present in every cultivar of Vitis vinifera, 2) they represent the biggest source of potential aromatic molecules, and 3) because these molecules incorporate glycosyl groups, their accumulation depends on the supply of carbohydrates and potentially on the carbon balance of the plant. The main objective of our work concerned the study of the impact of the S/S ratio on the biosynthesis of GAP, and its possible modulation depending on the genotype. Five questions were addressed: 1) Influence of the genotype on in the biosynthesis of GAP and its accumulation. The objective is to analyze the variability of GPA concentration at a given maturity stage among genotypes, including a set of varieties of V. vinifera (Marselan, Grenache, Muscat, Cabernet Sauvignon, Syrah and Chardonnay) and hybrids. V. vinifera x Muscadinia rotundifolia (G5). 2) Influence of the year on S/S balance and GAP concentration. 3) The impact of the S/S balance on the biosynthesis of GAP expressed in concentration (µg/L) and in quantity (µg/berry) as a function of grape development. 4) The relationship between primary and secondary metabolism (GAP and anthocyanins) and their modulation as a function of S/S balance. 5) Influence of the thinning date on the dynamics of GAP biosynthesis.The results showed that levels of glycosylated aromatic compounds varied according to genotype. Varieties whose grapes contain terpenic compounds (Muscat à petits grains blancs and the V. vinifera x Muscadinia rotundifolia G5 hybrid) showed the highest levels of GAP in both concentration and amount per fruit. These genotypes showed the highest values of GAP/sugar ratio. In general, genotypes producing non-colored berries had higher GAP/sugar ratios than colored berries. Despite strong inter-annual variation, the impact of the S/S ratio on GAP biosynthesis was found to be genotype-dependent.Thus, the GAP concentration was not affected during the modification of S/S in Cabernet-Sauvignon, while Muscat and Syrah showed large variations in GAP/berry contents as a function of the S/S ratio. The thinning date was also an important modulating factor in the increase of GAP, but varies according to genotype. In general, a significant decrease in the amount of primary metabolites accumulated in grapes is required to significantly increase the biosynthesis of secondary metabolites. This gain is very notable for anthocyanins, which are the most abundant carbon compounds after the primary metabolites (sugars and organic acids) in grapes. With regard to aromatic precursors, the impact is more moderate regardless of the family of glycosylated compounds

Thesis (MScAgric)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: An investigation into the effects of different mulches on the root environment, encompassing physical, chemical and biological factors of the soil, on two different soil types was done in the form of a field trial on ‘Cripps’ Pink’ apples. Three organic mulches were tested: compost, vermi-castings and woodchips, as well as an inorganic mulch, geotextile fabric, and were compared against clean cultivation. The organic treatments resulted in improved physical conditions (lower bulk densities) in the heavier soil, as well as, a reduction in temperature fluctuations and a general increase in soil temperatures during the seasons, in both sites. The geotextile fabric treatment resulted in increased soil moisture levels in the top 40 cm, predominantly in the heavier soil. The compost treatment resulted in high soil moisture levels in the top 40 cm only in the lighter soil. The vermi-castings treatment achieved superior results in terms of changing the nutrient status of the heavier soil. It resulted in significantly higher pH, P (phosphorus), N (nitrogen), K (potassium), Mg (magnesium), Zn (zinc), Mn (Manganese), B (boron), as well as the cation exchange capacity and some exchangeable cations, such as, Na+ (sodium ions), K+ (potassium ions) and Mg+ (magnesium ions). The compost treatment resulted in significantly higher Ca (calcium) and Ca+ (calcium ions) in the heavier soil compared to the other treatments. The organic mulches, including the woodchips treatment, consistently resulted in higher mineral levels and therefore performed the best in this regard and did so in the heavier soil. In contrast to the heavier soil, none of the treatments were successful in ameliorating the nutrient status of the lighter soil, with the exception however of the increased percentage C as a result of the compost and vermi-castings treatments. The compost treatment realised consistently higher mychorrizael colonization in both sites, however, not always significantly higher than the other treatments. The vermi-castings treatment realised consistently lower plant parasitic nematodes numbers. Higher free-living nematodes were also frequently realised during both seasons and in both sites. The organic mulches therefore proved promising with regard to soil biota. The organic treatments, with the exception of the vermi-castings treatment, resulted in improved root number and distribution in the heavier soil. The vermi-castings treatment resulted in a superior root environment and did not need to enhance its root system in order to achieve good fruit yield and quality. In contrast, the geotextile fabric treatment performed better in this regard in the lighter soil. The geotextile fabric treatment also achieved the lowest weed counts, quantified as winter weeds, in both sites. Yield efficiency, in the heavier soil, and the incidence of sunburn in both sites, were influenced by mulching. In the heavier soil, the woodchips treatment resulted in the highest yield efficiency and the compost treatment consistently resulted in the highest incidence of sunburn. In the lighter soil the control treatment resulted in the highest incidence of sunburn. The vermi-castings treatment consistently resulted in lower incidences of sunburn. Due to the limited quantification of irrigation in this trial, the consequence of irrigation on different mulches was not evaluated and should be considered for future research.
AFRIKAANSE OPSOMMING: ‘n Ondersoek na die effek van verskillende deklae op die wortelomgewing, insluitende fisiese, chemiese en biologiese grond faktore, is uitgevoer as ‘n veldproef of twee verskillende grondtipes, op ‘Cripps’ Pink’ appels. Drie organiese deklae is ge-evalueer naamlik: kompos, ‘vermi-castings’ en houtspaanders, asook ‘n anorganiese geotekstiel materiaal deklaag, en vergelyk met ‘n kontrole van skoon bewerking. Die organiese behandelings het verbeterde fisiese kondisies (laer bulkdigtheid) in die swaarder grond, asook ‘n verlaging in temperatuur fluktuasies en algemene verhoging in grondtemperature gedurende die seisoene in beide persele tot gevolg gehad. Die geotekstiel behandeling het verhoogde grondvog-vlakke in die boonste 40 cm in beide persele tot gevolg gehad, alhoewel dit meer prominent in die swaarder grond was. In sanderige grondperseel, het die kompos behandeling hoër grondvog-vlakke in die boonste 40 cm getoon as die ander behandelings. Die ‘vermi-castings’ behandeling het die beste resultate in terme van verbetering van nutrient- vlakke in die swaarder grond behaal. Dit het ‘n betekenisvol hoër pH, P (fosfaat), N (stikstof), K (kalium), Mg (magnesium), Zn (sink), Mn (mangaan), B (boron), katioon uitruilings kapasiteit en sommige uitruilbare katione soos , Na+ (natrium ione), K+ (kalium ione) en Mg+ (magnesium ione) as die ander behandelings in die swaarder gehad. Die kompos behandeling het betekenisvol hoër Ca (kalsium) en Ca+ (kalsium ione) in die swaarder grond getoon. Die organiese behandelings, insluitend die houtspaander behandeling, het dus in die geval, konstant die beste resultate te opsigte van hoër nutriënt vlakke in die swaarder grond getoon. Inteenstelling met die swaarder grond, het geen behandling daarin geslaag om die grondvoedingstatus van die sanderige grond te verbeter nie, met uitsondering die verhoogde persentasie C as ‘n resultaat van die kompos en ‘vermi-castings’ behandelings. Die kompos behandeling het konstant hoër mychorriza-kolonisasie teweeg gebring in beide persele, alhoewel nie altyd betekenisvol hoër as die ander behandelings was nie. Die ‘vermicastings’ behandeling het konstant ‘n laer persentasie plant-parasitiese nematodes getoon. Meer vry-lewende nematodes het ook gereeld oor die totale vier jaar wat die volledige proef gestrek het, op beide persele, voorgekom. Die organiese deklae toon dus belowende resultate in terme van biota. Die organiese behandelings, met uitsondering van die ‘vermi-castings’ behandeling, het verhoogte wortel ontwikkeling en -verspreiding in die swaarder grond tot gevolg gehad, Die ‘vermi-castings’ behandeling het ‘n besondere goeie wortelomgewing geskep en ‘n verbetering in die wortelstelsel om ‘n goeie opbrengs en kwaliteit te behaal, was nie nodig nie. Daarinteen het die geotekstiel behandeling beter resultate in die meer sanderige grond behaal. Die geotekstiel behandeling het ook die laagste onkruidstand in beide persele gehad. Opbrengs, in die swaarder grond, en die voorkoms van sonbrand in beide persele, is beïnvloed deur die dekgewasse. In die swaarder grondperseel het die houtspaanders behandeling die hoogste opbrengs getoon en die kompos behandeling, konstant die hoogste voorkoms van sonbrand. In die ligter, sanderige grondperseel, is die hoogste sonbrand voorkoms gemeet in die kontrole behandeling. Die ‘vermi-castings’ behandeling het die laagste sonbrand voorkoms getoon. Weens die beperkte kwantifisering van die besproeiing in die proef, is die gevolge van besproeiing op verskillende deklae nie ondersoek nie en behoort dit oorweeg te word in toekomstige navorsing.