Dissertations / Theses on the topic 'Pome fruit'

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Thinning is an important practice in pome fruit production which aims to ensure an optimal yield of high quality, large sized fruit as well as an adequate return bloom. In South Africa, pome fruit thinning is generally done by means of chemicals, with follow-up hand thinning. When thinning is effective, set and thus the hand thinning requirement should be reduced. This is important as labor cost associated with hand thinning is high and continually rising. Chemical thinning is weather dependent and can be environmentally harmful, which has led to a shift towards environmentally acceptable methods of thinning such as mechanical thinning. From 2013 until 2015 the mechanical string thinners, viz. Darwin 300™, BAUM, and Bloom Bandit™, were evaluated. These machines are used to thin trees during full bloom and reduce the number of flowers before fruit set. The aim of the trials was to reduce fruit set and therefore hand thinning requirement, while increasing fruit size and quality, maintaining yield and return bloom. A range of tractor speeds and rotational rates were evaluated with the Darwin 300™ on ‘Forelle’ pears and ‘Cripps’ Pink’ apples, while the BAUM was evaluated only on ‘Cripps’ Pink’ apples. The hand-held Bloom Bandit™ was evaluated on ‘Forelle’, ‘Cripps’ Pink’, ‘Fuji’ and ‘Cripps’ Red’. The tractor-driven mechanical thinning devices gave erratic results. The most consistent results on ‘Forelle’ were obtained using the Darwin 300™ at 5.2 km·h-1 and 300 rpm, while the BAUM gave no consistent results. The unreliability of results were due to South African pome fruit orchards currently being unsuitable for tractor-driven mechanical thinning machines. The ‘Forelle’ orchard trained to a Palmette system was the most suited for thinning, which is reflected in the more positive results obtained, but further improvements are possible. The Bloom Bandit™ effectively thinned pear and apple trees and increased fruit size without a decrease in yield or return bloom. More time is spent on thinning with the device compared to tractor-driven machines and this should be taken into account when considering using the Bloom Bandit™. Thinning intensities of 25%, 50% and 75% of clusters or flowers was applied to mature ‘Forelle’ and ‘Cripps’ Red’ trees during full bloom. Variable effects were seen on fruit set, yield was reduced to acceptable levels, while fruit size was improved in ‘Forelle’ but not ‘Cripps’ Red’. Results showed that when thinning mechanically, the aim should be to remove between 25% and 50% of flowers clusters in ‘Forelle’ and 50% of flowers clusters in ‘Cripps’ Red’. These levels of thinning gave the best results in terms of the remaining hand thinning requirements and improved return bloom in ‘Forelle’. We, however, only evaluated full cluster thinning and not within cluster thinning, which might also occur during mechanical thinning.
AFRIKAANSE OPSOMMING: Vruguitdunning is 'n belangrike praktyk in kernvrugproduksie en het ten doel om voldoende opbrengs van hoë kwaliteit, groot vrugte en voldoende opvolgblom te lewer. In Suid-Afrika, word kernvrugte gewoonlik chemies uitgedun, opgevolg met handuitdunning. Effektiewe uitdunning verminder set en dus die benodigde handuitdunning. Dit is belangrik aangesien die arbeidskoste verbonde aan die handuitdunning hoog is en voortdurend styg. Chemiese uitdunning is afhanklik van weerstoestande en dit kan ook omgewing-onvriendelik wees. Hierdie nadele het gelei tot 'n verskuiwing na omgewingsaanvaarbare metodes van uitdunning soos meganiese uitdun. Vanaf 2013 tot 2015 is die meganiese Darwin 300™, BAUM en Bloom Bandit™ uitdunmasjiene geëvalueer. Hierdie masjiene word gedurende volblom gebruik om blomme uit te dun en verminder die aantal blomme voor vrugset. Die doel van die proewe was om vrugset en dus die handuitdunvereiste te verminder met ‘n gepaardgaande verbetering in vruggrootte en kwaliteit sonder om opbrengs en opvolgblom nadelig te beïnvloed. Trekker en rotasiespoed is gevarieer met die Darwin 300 ™ op 'Forelle' pere en ‘Cripps’ Pink' appels, terwyl die BAUM net op 'Cripps' Pink' appels geëvalueer is. Daarbenewens was die hand-draagbare Bloom Bandit™ geëvalueer op 'Forelle', 'Cripps' Pink’, ‘Fuji’ en ‘Cripps' Red’. Die trekkergedrewe uitdunmasjiene het wisselvallige resultate opgelewer. Die mees konstante resultate op 'Forelle' is verkry met die Darwin 300™ teen 5.2 km·h-1 en 300 rpm, terwyl die BAUM nie konsekwente resultate gegee het nie. Die wisselvallige resultate van die Darwin 300™ en die BAUM is te wyte aan die boorde wat nie vir trekkergedrewe uidunmasjiene geskik is nie. Die 'Forelle’ boord, wat as 'n Palmette stelsel opgelei is, was die meeste geskik vir uitdunning, soos duidelik uit die positiewe resultate wat verkry is, maar verdere verbeterings is steeds moontlik. Die Bloom Bandit™ het peer en appel bome effektief uitgedun deur die handuitdunvereiste te verminder en vruggrootte te verbeter sonder verlies in opbrengs of opvolgblom. Meer tyd word gespandeer tydens uitdunning met hierdie toestel in vergelyking met trekkergedrewe masjiene, en dit moet in ag geneem word met oorweging van die Bloom Bandit™. Uitdunningsintensiteite van 25%, 50% en 75% van die trosse of blomme is tydens volblom toegepas op volwasse 'Forelle’ en ‘Cripps’ Red' bome. Vrugset het aansienlike variasie getoon terwyl opbrengs tot aanvaarbare vlakke verminder en vruggrootte verbeter is in 'Forelle' maar nie in 'Cripps' Red’ nie. Resultate het getoon dat die doel moet wees om tussen 25% en 50% van alle blomme in trosse in 'Forelle’ en 50% van blomme in trosse in 'Cripps’ Red’ tydens meganiese uitdunnig te verwyder. Hierdie vlakke van uitdunning het die beste resultate gegee ten opsigte van die oorblywende handuitdunvereistes en het opvolgblom in 'Forelle’ verbeter. Ons het egter net volledige trosse uitdunning gedoen en nie blomuitdunning binne die tros wat ook tydens meganiese uitdun kan plaasvind nie.

Thesis (MScAgric)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: Sunburn is a major problem in the apple industry worldwide. A kaolin product, M-97- 009 (100% kaolin), originally developed for insect control, was evaluated for its efficacy in controlling sunburn on pome fruit. Trials were conducted over two seasons in two different areas of the Western Cape, South Africa. During the first season, 'Royal Gala', 'Fuji' and 'Granny Smith' apples were evaluated in the Koue Bokkeveld. The kaolin was mixed with water and applied to the trees by means of a hand-gun regularly throughout the season. In addition to the effect on sunburn, effects on yield, colour development, snout beetle damage and other defects were determined. Sunburn was reduced on all the cultivars tested, although not significantly on 'Granny Smith'. Inconsistent effects on yield parameters were observed. The applications significantly reduced red colour on 'Fuji', but this problem was rectified by an improved application technique the following season. During the second season, additional apple cultivars and 'Rosemarie' pears were included in the trials. The apple trials were conducted in the Elgin area, and the 'Rosemarie' trial in the Koue Bokkeveld. Surround™ (95% kaolin) was applied to the trees by means of a commercial "blower". The effects on sunburn, yield, colour development and fruit maturity were determined. In contrast to the previous season, sunburn was not reduced on any of the cultivars examined. Yield parameters were not affected except in the case of 'Royal Gala' where the number of fruit was increased, and 'Cripps' Pink' where the number of fruit was reduced. Fruit colour was not affected in the apple cultivars, but chroma of 'Rosemarie' pears was reduced, indicating a less intense colour. The kaolin applications had a variable effect on fruit maturity. The effect of the foliar applications on photosynthetic photon flux density (PPFD), photosynthetic rate, stomatal conductance and transpiration rate was determined. In addition to these spot measurements, photosynthetic light response curves were determined. Measurements were taken on both the inner and outer canopies The applications significantly reduced photosynthetic rates in the inner canopy and reduced the apparent quantum efficiency of leaves on the outer canopy. No significant effect on PPFD was found. It appears that the white coating reflects light and allows less light to penetrate the leaf, thus reducing photosynthesis. Surround™ treatments could not counteract the damaging effects of the high temperatures experienced in the Western Cape during this season and was not effective as a control measure for sunburn. This does not appear to be a commercially viable solution for the sunburn problem and it would be worthwhile to investigate the use of alternative options, such as evaporative cooling.
AFRIKAANSE OPSOMMING: Sonbrand is een van die grootste probleme wat wêreldwyd in die appelbedryf ondervind word. 'n Nuwe produk, M-97-009 (100% kaolien), is oorspronklik ontwikkel vir insekbeheer in geïntegreerde plaagbeheer, maar daar is beweer dat dit moontlik sonbrand op kemvrugte kan verminder. Proewe is oor twee seisoene uitgevoer in die Koue Bokkeveld en ook in die Grabouw-omgewing in die Wes-Kaap. Tydens die eerste seisoen is die effek van M-97-009 op 'Royal Gala', 'Fuji' en 'Granny Smith' appels beoordeel. Die kaolien is met water gemeng en deur die loop van die seisoen met 'n handspuit op die bome gespuit. Die effek van die produk op sonbrand, oesgrootte, vruggrootte, kleurontwikkeling, kalanderskade en ander defekte is bepaal. Sonbrand is op alle kultivars verminder, alhoewel nie betekenisvolop 'Granny Smith' nie. Die effek van kaolien op oesparameters was rue konsekwent nie. kleurontwikkeling op 'Fuji' benadeel, heel moontlik Die toedienings het as gevolg van die toedieningstegniek. Met verbeterde toedieningsmetodes die volgende seisoen, is kleurontwikkeling van 'Fuji' nie benadeel nie. Tydens die tweede seisoen is die effek van kaolien op nog appelkultivars en 'Rosemarie' pere ge-evalueer. Die appelproewe is in Elgin uitgevoer, terwyl die 'Rosemarie'-proefin die Koue Bokkeveld uitgelê is. Surround™ (95% kaolien) is met kommersiële spuitpompe toegedien. Weereens is die effek van die produk op sonbrand, oesgrootte, vruggrootte, kleurontwikkeling en vrugrypheid bepaal. Sonbrand is nie verminder nie. Vruglading tydens oes is nie betekenisvol beïnvloed nie, behalwe in die geval van 'Royal Gala' waar die vruglading verhoog is, en 'Cripps' Pink' waar daar minder vrugte op die gespuite bome was. Die Surround™ toedienings het geen uitwerking op kleur van appels gehad nie, maar het die chromawaarde van 'Rosemarie' pere verlaag, d.w.s die vrugkleur was minder intens. Die kaolienspuite het 'n uiteenlopende effek op vrugrypheid gehad. Fotosintetiese foton vloeddigtheid (FFV), fotosintesetempo, huidmondjieweerstand en transpirasietempo is gemeet en ligreponskurwes van beide die buitenste en binneste blaardak is bepaal. Die Surround™ toedienings het fotosintese van blare ill die binneste gedeelte van die blaardak verminder en die kwantumdoeltreffendheid van blare op die buitenste deel van die blaardak verminder. Geen betekenisvolle effek is op FFV gekry nie. Dit wil voorkom asof die wit laag kaolien op die bome lig weerkaats en veroorsaak dat minder lig na die blaar deurdring. Dit verminder dan die fotsintesetempo. Met die baie warm weer wat in die Wes-Kaap gedurende die tweede seisoen ervaar is, kon die SUITound™behandelings nie sonbrand verhoed nie. Dit wil voorkom asof Surround™ nie 'n baie doeltreffende oplossing in kommersiële boorde sal wees nie. Alternatiewe oplossings, soos byvoorbeeld evaporatiewe verkoeling, saloorweeg moet word.

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Apple (Malus pumila Mill.) and pear (Pyrus communis L.), commonly known as pome fruits, are important deciduous fruit crops in South Africa. The challenges of climate change, disease incidence, distant markets and fluctuating consumer preferences necessitate new cultivars. The Agricultural Research Council (ARC) Infruitec-Nietvoorbij conducts a breeding programme aimed at developing new cultivars that are well adapted, resistant to pests and diseases and good storage potential. A recent review of the pome fruit gene banks, the breeders’ raw material, revealed misidentification and poor characterisation limitating the efficiency of its utilisation. To address these problems, the current study used microsatellite markers to investigate the trueness to type of accessions in the ARC gene banks. In addition, accessions of apple identified as true to type, were genotyped for the ACS1 gene involved with ethylene production and fruit ripening. Two sets of 12 microsatellite markers recommended by a European working group on Pyrus/Malus, one for apple and one for pear, were utilised to fingerprint 540 apple and 197 pear accessions. Eleven and eight of 12 markers, were used respectively to successfully discriminate across the apple and pear accessions, with the exception of clones and sports of particular cultivars. Where possible, fingerprints were compared with those of their reported parents. The use of recommended markers facilitated the comparison of ARC pear accessions with those of the collection in Brogdale (UK). Trueness to type of accessions were established and misidentified accessions were also detected. A similar comparison will be conducted for apple when the Brogdale apple accessions fingerprints become available. Several accessions were found to be false, 78 apple and 22 pear, and removal from the collection was recommended. For ACS1 genotyping of 292 apple accessions, customised fluorescently labelled ACS1-Pr were used rather than the published ACS1-5 primers. Of the 292 apple accessions, 29 were homozygous for the b allele associated with low ethylene and good storage potential. Novel size variation in one allele of the ACS1 gene, was detected in some Malus species and ornamental hybrids. Successful amplification in a multiplex reaction was achieved and proves to be a cost effective method for simultaneous molecular fingerprinting and ACS1 genotyping. True to type material will facilitate confident use of genetic resources in the breeding programmes, and the ACS1 genotypes will identify candidate parents for developing good storage performing cultivars for distant markets.
AFRIKAANSE OPSOMMING: Summary not available

Ethylene antagonists offer an effective way to prevent the deleterious effects of ethylene in climacteric fruits. 1-Methylcyclopropene, 1-hexylcyclopropene, (S)-(-)- limonene and trans-cinnamaldehyde were evaluated as ethylene antagonist to extend the storage life of apple and pear fruits. 1-Methylcyclopropene was most efficient followed by 1-HCP, (S)-(-)-limonene and trans-cinnamaldehyde in suppressing and delaying climacteric ethylene production, extending cold and controlled atmosphere storage life and maintaining fruit quality depending upon cultivar and storage period.

Thesis (MScAgric (Plant Pathology))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: A survey was undertaken on apple and pear trees in the Western Cape Province to determine the aetiology of trunk diseases with reference to trunk diseases occurring on grapevine. Grapevine trunk diseases cause the gradual decline and dieback of vines resulting in a decrease in the vine’s capability to carry and ripen fruit. In recent years, viticulture has been expanding into several of the well established pome fruit growing areas. The presence of trunk pathogens in pome fruit orchards may affect the health of the pome fruit trees as well as cause a threat to young vineyards planted in close proximity to these potential sources of viable inoculum. Several genera containing species known to be involved in trunk disease on pome fruit and grapevine were found, including Diplodia, Neofusicoccum, Eutypa, Phaeoacremonium and Phomopsis. Diplodia seriata and D. pyricolum, were isolated along with N. australe and N. vitifusiforme. Four Phaeoacremonium species, P. aleophilum, P. iranianum, P. mortoniae and P. viticola, two Phomopsis species linked to clades identified in former studies as Phomopsis sp. 1 and Phomopsis sp. 7, and Eutypa lata were found. In addition, Paraconiothyrium brasiliense and Pa. variabile, and an unidentified Pyrenochaetalike species were found. Of these the Phaeoacremonium species have not been found on pear wood and it is a first report of P. aleophilum occurring on apple. This is also a first report of the Phomopsis species and Eutypa lata found occurring on pome trees in South Africa Two new coelomycetous fungi were also found including a Diplodia species, Diplodia pyricolum sp. nov., and a new genus, Pyrenochaetoides gen. nov. with the type species, Pyrenochaetoides mali sp. nov., were described from necrotic pear and apple wood. The combined ITS and EF1-α phylogeny supported the new Diplodia species, which is closely related to D. mutila and D. africana. The new species is characterised by conidia that become pigmented and 1-septate within the pycnidium, and that are intermediate in size between the latter two Diplodia species. Phylogenetic inference of the SSU of the unknown coelomycete provided bootstrap support (100%) for a monophyletic clade unrelated to known genera, and basal to Phoma and its relatives. Morphologically the new genus is characterised by pycnidial with elongated necks that lack setae, cylindrical conidiophores that are seldomly branched at the base, and Phoma-like conidia. The phylogenetic results combined with its dissimilarity from genera allied to Phoma, lead to the conclusion that this species represents a new genus. A pathogenicity trial was undertaken to examine the role of these species on apple, pear and grapevine shoots. N. australe caused the longest lesions on grapevine shoots, while Pyrenochaetoides mali, Pa. variabile, D. seriata and P. mortoniae caused lesions that were significantly longer than the control inoculations. On pears, D. pyricolum and N. australe caused the longest lesions, followed by D. seriata and E. lata. On apples, the longest lesions were caused by N. australe and P. iranianum. D. seriata, D. pyricolum, E. lata, N. vitifusiforme, Pa. brasiliense, P. aleophilum and P. mortoniae also caused lesions on apple that were significantly longer than the control. The study demonstrated that close cultivation of grapevine to apple and pear orchards may have inherent risks in terms of the free availability of viable inoculum of trunk disease pathogens.
No Afrikaans abstract available.

Blue mold (Penicillium expansum), grey mold (Botrytis cinerea) and mucor rot (Mucor piriformis) are important post-harvest diseases of pome fruit in British Columbia and throughout the world causing annual losses of 5 – 20%. Identification and quantification using novel DNA macroarray technology may assist in the development of prediction models and disease forecasting. Post-harvest pathogens were monitored and quantified throughout the growing season in four apple orchards in the Okanagan Valley, BC in 2007 and 2008. Their detection was variable due to field and year differences. The average percent detection of P. expansum (27.4%) and M. piriformis (19.2%) was higher than that of B. cinerea (6.2%). There was a positive correlation between total post-harvest pathogen detection in aerial samples just prior to harvest and after harvest in naturally infected fruit (r = 0.74; p = 0.09). Pseudomonas fluorescens (isolates 1-112, 2- 28, 4-6) and Serratia plymuthica (isolate 6-25), isolated from the rhizosphere of legumes, were investigated for their biological control capabilities in semi-commercial storage conditions at 1°C in air and commercial storage conditions in controlled atmosphere and with 1-methylcyclopropene (1-MCP) application. Overall, isolate 6-25 provided control in the greatest number of treatments (51.7%) while isolate 1-112 provided the greatest level of control (75.8%) in treatments where significant control was exhibited. Isolate 4- 6 was tagged with green fluorescent protein to gain insight into bacterial antagonist population and survival dynamics. Alone, its population increased 10 fold after 30 d in storage at 1°C and then decreased to concentrations similar to those at inoculation. In the presence of the pathogen, 4-6-gfp increased then decreased after 30 d in storage at 1°C to undetectable amounts. These data provide greater insight into the prediction, control and population dynamics of pathogens and biological control agents as a means of preventing and controlling post-harvest storage diseases in pome fruit.

Study project (MBA)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: No effective programmed extension exists in the South African pome fruit industry. There is a lack of farmer response and involvement, a lack of coordinated dissemination of information and no systematic and scientific approach in the development of extension programmes for the industry. Particularly important is the lack of a systematic conceptualisation of problems and specifically the lack of identification of the most direct determinants of behaviour (the psychological field forces) and a lack of the systematic addressing of these human constraints. DOvel's revised extension programme model was used as basis for this study. It included the identification, prioritisation, conceptualisation and determination of perceived problems that need to be addressed in the extension programmes. The most important identified problems that needs attention in an extension programme are producers' knowledge relating to all aspects of strategic planning (ie knowledge of basic principles, what is attainable, the advantages and disadvantages and the practical implementation), knowledge relating to the practical implementation of irrigation, bitter pit control and practices to increase fruit size, and knowledge that relates to basic principles of marketing.
AFRIKAANSE OPSOMMING: Geen doelgerigte geprogrammeerde voorligting bestaan vir die Suid-Afrikaanse kernvrugindustrie nie. Daar is 'n tekort aan produsentebetrokkenheid, 'n tekort aan gekoordineerde verspreiding van inligting en daar is geen sistematiese en wetenskaplike benadering in die ontwikkeling van voorligtingsprogramme vir die industrie nie. Besonder belangrik is die afwesigheid van 'n sistematiese konseptualisering van probleme en meer spesifiek die tekort aan die identifisering van die meer direkte determinante van gedrag (die psigiese veldkragte) en die aanspreek van hierdie menslike beperkings. DOvel se hersiene model vir geprogrameerede voorligting het as basis gedien vir die studie. Die studie het ingesluit die identifisering, prioritisering, konseptualisering en bepaling van produsente se persepsie van aangespreek behoort te word. probleme wat binne voorligtingsprogramme Die belangrikste probleme wat in die studie geïdentifiseer is wat aandag moet geniet in voorligtingsprogramme is die produsente se kennis van alle aspekte van strategiese beplanning (kennis van basiese beginsels, kennis wat betrekking het op wat bereikbaar is met strategiese beplanning, die voor- en nadele daarvan asook die praktiese implementering van strategiese beplanning), kennis wat betrekking het op die praktiese implementering van besproeiing, bitterpit beheer en die verbetering van vruggroote asook die kennis wat betrekking het op die basiese beginsels van bemarking.

Thesis (PhD(Agric))--Stellenbosch University, 2009.
ENGLISH ABSTRACT: The global movement in agriculture is towards more environmentally friendly, sustainable production practices, since the role of soil microbial functions in ensuring crop production and soil fertility has become more evident in agricultural systems. Furthermore, with the impeding phase-out of methyl bromide, apple replant disease (ARD) is becoming an increasingly important problem and biological management practises are needed. Since microbial activity is generally carbon-limited in agricultural soil, it is widely accepted that management practices providing a range of organic compounds on a regular basis will tend to maintain an active and diverse microbial population. It was hypothesised that the application of various biological amendments can affect soil microbial numbers and function, thereby having a positive effect on fruit tree growth and yield. The effect of continued applications of organic material, various microbial inoculants and biostimulants on tree performance were evaluated in conventional management systems. Field trials were established in a conventional pear orchard, potential apple replant disease sites, as well as an optimally managed, high density apple orchard under controlled fertigation. The use of compost, compost extracts, a Bacillus inoculant and humates were investigated intensively. Furthermore, to improve our understanding of soil biological systems a combination of simple, practical methods were used to evaluate the effect of biological amendments on soil microbial properties and effects were related to tree performance. Regular application of compost extract in combination with compost showed the most significant effect in improving tree performance in commercial pome fruit orchards under various conditions. In the pear orchard, cumulative yield over the first two seasons was improved by more than 50% compared to controls, while in the fertigated orchard yield was improved by 22%. Biological amendments also showed improved growth in orchards suffering from stunted growth symptoms typical of ARD. However, in severe ARD cases methyl bromide fumigation showed the most consistent effects. Other biological amendments which showed positive effects on yield were application of Bacillus inoculants (Biostart®) in combination with a labile C source and a low dosage humate product, as well as a combination of compost and humates. It was clear that a combination of labile organic matter and a diverse group of microorganisms showed most promise. Although for some specific treatments increased microbial numbers and activity may have resulted in improved tree performance, in general, changes in culture-based plate counts, soil enzyme activity and carbon utilisation profiles could not be used as an indicator of yield. It was suggested that improved synchronisation of nutrient release and plant uptake, as well as microbial phytohormone production, may play an important role in improving tree performance with application of biological amendments. More research is needed on the exact mechanisms through which compost extracts improve yield and studies on root growth proliferation, as well as effects in the rhizosphere are recommended.
AFRIKAANSE OPSOMMING: Binne lanbouverband is daar tans wêreldwyd die neiging om die uitwerking van produksie-praktykte op die omgewing in ag te neem en sodoende meer verantwoordelik op te tree. Omdat die belangrike rol wat grondmikro-organisme funksionering in volhoubare verbouingspraktyke speel nou deeglik besef word, word meer volhoubare bestuurspraktyke bepleit. Hiermee saam, noodsaak aspekte soos die uitfasering van metielbromied vir die beheer van appelhervestigingsiekte, dat biologiese bestuurspraktyke meer aandag geniet. Daar word geredelik aanvaar dat gereelde toediening en aanvulling van organiese materiaal ‘n aktiewe, diverse mikrobe populasie in die grond tot gevolg sal hê. Die hipotese is gestel dat die toediening van ‘n verskeidenheid biologiese produkte grondmikrobe getalle en werking gunstig kan beïnvloed. Dit kan moontlik weer aanleiding gee tot positiewe reaskies wat die groei en drag van vrugtebome betref. In hierdie studie is die uitwerking van voortgesette toedienings van organiese materiaal, mikrobiese inokulante, asook biostimulante, op die prestasievermoë van vrugtebome ondersoek. Veldproewe is uitgelê in ‘n konvensionele peerboord, verskeie boorde met moontlike appelhervestigingsiekte probleme, asook ‘n hoëdigtheidsaanplanting appelboord onder optimale bestuur. ‘n Deeglike ondersoek is gedoen met betrekking tot die gebruik van kompos, komposekstrak, Bacillus-inokulante en humate. Eenvoudige, praktiese metodes is aangewend om vas te stel hoe biologiese toevoegings grondmikrobe eienskappe beïnvloed en of dit verband hou met veranderinge in boomprestasie. Die studie het aangetoon dat die gereelde toediening van komposekstrak saammet kompos, betekenisvolle verbetering in boomprestasie van kernvrugboorde teweeg bring onder verskeie omstandighede. Die kumulatiewe opbrengs van ‘n peerboord is oor twee seisoene met meer as 50% verhoog teenoor die kontrole. In ‘n optimaal bestuurde appelboord onder sproeibemesting, is opbrengs met 22% verhoog in vergelyking met die kontrole. Biologiese toevoegings het ook groei verbeter in boorde waar appelhervestigingsiekte bome se groei vertraag het. In die geval van ernstige appelhervestigingsimptome het metielbromied egter steeds die mees konstante positiewe uitwerking gehad. Ander biologiese toevoegings wat ‘n gunstige uitwerking op opbrengs getoon het, was ‘n kombinasie van Bacillus inokulante, ‘n lae dosis humaat en ‘n aktiewe koolstofbron, asook kompos in kombinasie met humate. Dit is duidelik dat ‘n kombinasie van ‘n maklik afbreekbare koolstofbron (soos kompos) tesame met ‘n diverse groep mikroorganismes mees belowend is vir gebruik in biologiese verbouingssisteme. Resultate toon dat veranderings in aantal organismes gemeet deur plaattellings, die aktiwiteit van grondensieme, en verbruikspotensiaal van verskillende koolstofbronne, nie as ‘n aanduiding van boomprestasie gebruik kan word nie. Daar is voorgestel dat verbeterde sinkronisasie van voedingselementvrystelling en plantopname, sowel as produksie van plantgroeihormone deur mikrobe, moontlik ‘n rol speel by boomreaksies op biologiese toevoegings. Meer navorsing wat verband hou met die meganisme waardeur komposekstrak opbrengs verbeter, is nodig. Verder word studies op fynwortelontwikkeling sowel as aspekte van die wortelrisosfeer aanbeveel.

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Increasing pressure on food production and the concern over maintenance of biodiversity and ecosystem services is creating an urgent need to future-proof food production, while maintaining the natural environment for future generations. Within the Cape Floristic Region (CFR) biodiversity hotspot in the Western Cape of South Africa, deciduous fruit is widely grown, contributing significantly to the local economy. To ensure access is maintained to important export markets, this study reviews the current available pest control options with focus on techniques able to preserve the biodiversity of the CFR, while simultaneously providing effective control over arthropod pests in pome fruit. A scenario planning technique is then used to depict potential future scenarios and the options we have in dealing with them. Emphasis here is placed on economically important arthropod species, particularly Mediterranean fruit fly Ceratitis capitata (Wiedemann) and codling moth Cydia pomonella (L.). Biological control (biocontrol) is discussed in detail, covering predators, parasitoids and pathogens. Biocontrol is an important, sustainable pest control measure. However, certain risks associated with releasing living organisms into the environment must not be ignored. Monitoring of release programmes is essential. The sterile insect technique (SIT) offers a species-specific approach to controlling pests. However, the technique is research and management intensive. Globally SIT has shown great success, but lack of financial support has limited SIT uptake locally. SIT has shown increased effectiveness as an integrated technique, particularly with parasitoid release and pheromone-based mating disruption. The management of orchards as agroecosystems shows that preservation of natural vegetation and beneficial plant species increases crop resilience, encourages conservation biological control and maintains crop health. The importance of area-wide control is discussed under each section, as a favourable strategy which deals with entire pest populations rather than isolated farm-by-farm approaches. Other techniques covered include pheromone-based mating disruption, attract-and-kill and physical barriers such as sticky tree-bands, which all show integration potential with biologically-based techniques while minimising insecticide application. The usefulness of insecticides as a curative approach is recognised, and ways of preserving insecticide life-spans by limiting insecticide resistance are discussed. Social, economic, political, environmental and technological driving forces are used to develop four realistic future scenarios for pome fruit production in the CFR. The scenarios are based on the extremes of two key uncertainties: development of resistance to chemical insecticides, and changes in legislation regulating insecticide usage. The options we face in dealing with each potential scenario, with the suite of arthropod pest control techniques currently developed, is discussed. It is hypothesised that a best-case scenario, in which environmentally-friendly techniques which support healthy, productive agroecosystems, can be reached. We should carefully assess our options, and begin to shift pest control from a predominantly chemical basis to one in which habitat management and biocontrol form the basis of control, with techniques such as SIT, mating disruption and physical barriers assisting in creating holistic arthropod pest control systems. In light of the uncertainty that the future holds, a scenario planning exercise such as this, can assist in decision making today that will best prepare us to deal with future threats such as climate change and new pest invasions.
AFRIKAANSE OPSOMMING: Toenemende druk op voedselproduksie en kommer oor die handhawing van biodiversiteit en ekosisteemdienste lei tot „n dringende behoefte om voedselproduksie toekoms-bestand te maak, asook om tegelykertyd die natuurlike omgewing vir toekomstige generasies te bewaar. Binne die Kaap Floristiese Streek (KFS) „biodiversiteitskern‟ in die Wes-Kaap van Suid-Afrika word sagte vrugte algemeen verbou en lewer „n aansienlike bydrae tot die plaaslike ekonomie. Om toegang tot belangrike uitvoermarkte te verseker ondersoek hierdie studie die plaagbeheer opsies tans beskikbaar, met die fokus op tegnieke wat die biodiversiteit van die KFS kan bewaar en tegelykertyd effektiewe beheer oor geleedpotige plae van kernvrugte kan verskaf. „n Scenario-beplannings-tegniek word dan gebruik om moontlike toekomstige scenario‟s en die opsies tot ons beskikking om hulle te hanteer, uit te beeld. Klem word hier geplaas op geleedpotige spesies van ekonomiese belang, veral die Mediterreense vrugtevlieg, Ceratitis capitata (Wiedemann) en die kodlingmot Cydia pomonella (L.). Biologiese-beheer (biobeheer) word in diepte bespreek, en dek predatore, parasiete en patogene. Biobeheer is „n belangrike, volhoubare plaagbeheer-middel; alhoewel sekere risiko‟s verbonde met die vrystelling van lewende organismes in die omgewing nie verontagsaam moet word nie. Dit is noodsaaklik dat vrystellingsprogramme gemoniteer word. Die steriele-insek-tegniek (SIT) bied „n spesies-spesifieke benadering tot die beheer van plae, alhoewel dit navorsings- en bestuursintensief is. SIT het wêreldwyd al groot suksesbehaal, maar „n tekort aan finansiële ondersteuning het die plaaslike toepassing van SIT beperk. SIT het verhoogde effektiwiteit as „n geïntegreerde tegniek vertoon, veral met die verlies van parasiete en feromoon gebaseerde parings-ontwrigting. Die bestuur van boorde as agro-ekosisteme wys dat die bewaring van natuurlike plantegroei en voordelige plant spesies oes-herstelvermoë verhoog, bewaring-biologiese-beheer aanmoedig en oes-welstand handhaaf. Die belang van streekswye beheer word bespreek onder elke afdeling as „n gunstige strategie wat te doen het met algehele plaagbevolkings, eerder as afsonderlike plaas-tot-plaas benaderings. Ander tegnieke wat gedek word sluit in feromoon gebaseerde parings-ontwrigting, lok-en-doodmaak en fisiese versperrings soos taai boom-bande, wat alles integrasie-potensiaal wys met biologies gebaseerde tegnieke en tegelykertyd insekdoder aanwending verminder. Die nuttigheid van insekdoders as „n herstel benadering word erken en maniere om die leffektiwiteit van insekdoders te behou deur insekdoder-weerstand te beperk, word bespreek. Sosiaal-, ekonomies-, polities-, omgewings- en tegnologies-gedrewe kragte word gebruik om vier realistiese toekomstige scenario‟s vir kernvrug-produksie in die KFS te ontwikkel. Die scenario‟s is baseer op die ekstreme van twee belangrike onsekerhede: ontwikkeling van weerstand teen chemiese insekdoders, en veranderinge in wetgewing wat die gebruik van insekdoders reguleer. Die opsies wat ons in die gesig staar om elke potensiële scenario te hanteer met die verskeidenheid van geleedpotige plaagbeheer-tegnieke tans ontwikkel is, word bespreek. Dit word veronderstel dat „n beste scenario, waar omgewings-vriendelike tegnieke wat gesonde, produktiewe agro-ekosisteme onderhou, bereik kan word. Ons moet ons opsies versigtig assesseer, en begin om plaagbeheer vanaf „n oorwegend chemiese basis te skuif na een waar habitat-bestuur en biobeheer die basis van beheer vorm, en waar tegnieke soos SIT, parings-ontwrigting en fisiese versperrings help om holistiese geleedpotige-plaagbeheer sisteme te vorm. In die lig van die onsekerheid wat die toekoms inhou, kan „n scenario-beplannings oefening soos hierdie besluitneming vandag aanhelp wat ons die beste sal voorberei vir die hantering van toekomstige bedreigings soos klimaats-verandering en nuwe en vreemde plaag-indringing.

Thesis (MScAgric)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Inadequate cooling of produce after it has been packed into ventilated packaging can result in inconsistent fruit quality. Misalignment of ventilation holes during stacking as well as the use of internal packaging, such as trays, polyliner bags and thrift bags reduces airflow distribution through the packaging. Consequently, the complex needs of maintaining the cold chain of perishable produce and the considerable variations in packaging designs have made it challenging to find an optimal ventilated package and stacking arrangement. The aims of this study were, therefore, to assess the status of ventilated packaging in the South African pome fruit industry, and to characterize the effects of package design and multi-scale packaging components on the resistance to airflow and cooling performance of apples under forced-air cooling conditions. A survey of the pome fruit industry identified over twenty packaging designs which were grouped into eleven unique designs and further categorised into either ‘display’ or ‘telescopic’ designs. Although South African fruit industry standards recommend ventilation areas of at least 5%, the ventilation areas of package designs identified from the survey varied considerably between <1 and 11%. Furthermore, the study showed that use of stacking renders many of the ventilation holes ineffective, due to blockages from adjacent cartons. The contribution of each component of the multi-scale packages used for handling apples was determined by analysis of pressure drop during forced-air cooling. The results showed when utilising a combination of cartons, fruit trays and plastic liner bags, the total pressure drop contribution of the cartons (8%) and fruit trays (3%) was minimal, while the use of plastic liner bags contributed 89%. However, in a carton and thrift bag packaging combination, the thrift bags contributed 66% to the pressure drop while the carton contributed 34%. The cooling results indicated a negative correlation between the total stack ventilation area and the cooling heterogeneity. In addition, the airflow velocity was correlated positively with fruit cooling rate and negatively with total moisture loss. Fruit packed inside polyliner bags had cooling rates four times slower than fruit on trays and three times slower in thrift bags. The use of liner bags blocked the ventilation holes, thereby reducing the airflow velocity. As a result of the longer cooling times in the polyliner bags, fruit remained at higher temperatures for longer periods, resulting in up to three times more moisture loss during forced-air cooling. In addition, a temperature gradient formed due to a progressive increase in air temperature through the stack, thereby resulting in a similar gradient of moisture loss. This research showed that airflow velocity and distribution were the most important factors contributing to the effectiveness of fruit cooling in multi-scale packaging. From a cold chain perspective, future packaging designs should therefore focus on optimising ventilation characteristics and alignment during stacking to ensure adequate airflow. Given the contribution of internal packaging to high resistance to airflow, such packaging components should be used with caution and only when necessary to meet physiological and market requirements.
AFRIKAANSE OPSOMMING: Onvoldoende verkoeling van vars produkte nadat hulle verpak is kan lei tot wisselende vruggehalte. Wanbelyning van ventilasiegate tydens stapeling sowel as die gebruik van interne verpakking soos rakkies (eng. “trays”), poli-etileensakke en drasakkies (eng. “thrift bag”) verminder die lugverspreiding deur die verpakking. Komplekse behoeftes om bederfbare produkte in die koue ketting te behou en die aansienlike verskille in verpakkingsontwerpe het dit 'n uitdaging gemaak om 'n optimale geventileerde verpakking en stapelskikking of -rangskikking te vind. Die doelwitte van hierdie studie was dus om die status van geventileerde verpakking in die Suid-Afrikaanse kernvrugbedryf te asseseer, en die gevolge van die verpakkingsontwerp en multi-skaal verpakkingskomponente op die weerstand teen lugvloei en verkoeling van appels onder geforseerde lugverkoeling te bepaal. ‘n Opname van die kernvrugbedryf het meer as twintig verpakkingsontwerpe geïdentifiseer, wat in elf unieke ontwerpe gegroepeer is en verder getipeer word in ‘vertoon’ en ‘teleskopiese’ kartonontwerpe. Alhoewel die Suid-Afrikaanse vrugindustrie-standaarde ventilasie areas van ten minste 5% aanbeveel, het die ventilasie areas van die verpakkingsontwerpe geïdentifiseer uit die opname aansienlik gewissel tussen <1 en 11%. Verder het die studie getoon dat gebruik van stapeling baie van die ventilasiegate ondoeltreffend laat weens blokkasies veroorsaak deur aangrensende kartonne. Die bydrae van elke komponent van die multi-skaal verpakkingskombinasies gebruik vir die hantering van appels was bepaal deur analise van die afname in lugdruk tydens geforseerde lugverkoelingskondisies. Die resultate het getoon dat wanneer ‘n kombinasie van kartonne, polietileensakke en vrugte plus rakkies gebruik word, die bydrae van die kartonne (8%) en vrugte plus rakkies (3%) tot die totale afname in lugdruk minimaal was, terwyl die gebruik van polietileensakke ‘n 89% bydrae gemaak het. In ‘n karton en drasakkie kombinasie het die drasakkies 66% bygedra tot die afname in lugdruk, terwyl die karton 34% bygedra het. Die verkoelingsresultate het 'n negatiewe korrelasie getoon tussen die totale stapelventilasie-area en die verkoelingsheterogeniteit. Daarbenewens was die lugvloeisnelheid positief gekorreleer met vrugverkoelingstempo en negatief gekorreleer met totale vogverlies. Die verkoelingstydperk van vrugte in die poli-etileensakke was vier keer langer as die rakkie met vrugte kombinasie en drie keer langer in die drasakkies. Die poli-etileensakke het die ventilasiegate versper en dus die lugvloeisnelheid verlaag. Weens die langer verkoelingstye in die poli-etileensakke was vrugte veel langer aan hoër temperature blootgestel, wat uiteindelik gelei het tot drie keer meer massaverlies gedurende geforseerde lugverkoeling. Daarby het ‘n temperatuurgradiënt gevorm as gevolg van ‘n progressiewe verhoging in lugtemperatuur deur die stapel wat gelei het tot ‘n gelykstaande gradiënt van vogverlies. Hierdie navorsing het getoon dat die lugvloeisnelheid en -verspreiding die belangrikste faktore was wat die doeltreffendheid van vrugverkoeling in multi-skaal verpakking geaffekteer het. Uit 'n koelketting perspektief moet die toekomstige verpakkingsontwerpe dus fokus op die optimalisering van ventilasie eienskappe en belyning (eng. “alignment”) tydens stapeling om voldoende lugvloei te verseker. Gegewe die bydrae van die interne verpakking tot hoë weerstand teen lugvloei, moet sulke verpakkingskomponente met omsigtigheid gebruik word en slegs wanneer dit nodig is om aan markvereistes te voldoen.

The South African economy has in the past been categorised as carbon intensive due to an energy and capital intensive development path and an associated set of economic activities termed the minerals-energy complex. International export markets, specifically the European Union (EU), are systematically applying pressure on imported products with a high carbon footprint through potential trade barriers, border tariffs and consumer lobbying. The objective of this research is to determine whether South African pome fruit has a higher global warming potential (GWP) per kg fruit compared to pome fruit cultivated and packaged in other countries. Following on from this finding, is to determine whether the Greenhouse Gas (GHG) emissions for pome fruit in South Africa are declining, ,as could be expected based upon the declining carbon intensity of the South African economy since 1990 and efficiency improvements in the industry itself. The Attributional Life Cycle Assessment (ALCA) methodology is used to determine the Global Warming Potential (GWP) per kg fruit for multiple boundaries within the value chain, retrospectively for the years 2000, 2010 and prospectively for 2020. The product system boundary includes the farm, packhouse, controlled atmosphere store (CA) and cold store (CS). For the Life Cycle Inventory (LCI), the temporal variations in pome fruit cultivation, packing and storing for the export and local market are taken into account for each of the years studied. Using the single issue characterisation methods – the GHG Protocol and the IPCC GWP 2013 100a – the results for each of the years under study are compared at a value chain, boundary and activity level. The results indicate that the baseline GWP result for South African pome fruit in the year 2000 was relatively high compared to similar international LCA research on apples and pears during this period. However, the results for the years 2010 and 2020 clearly indicate a sustained decline in relative GHG emissions of South African pome fruit according to the GWP indicator result per kg fruit and the normalised results for the industry. It is clear that there has been an increase in eco-efficiency in a number of farming and agro-processing practices since 2000 which correlates to the declining CO2e emissions in the boundaries and value chain of South African pome fruit. The carbon intensity and efficiency of the pome fruit value chain is also determined for each year using the kg CO2e per kg fruit and the industry revenue for a specific year (ZAR 2010 adjusted for PPI). The findings support the hypothesis that the carbon intensity of the pome fruit industry has indeed declined since the year 2000. This decline in carbon intensity represents a relative decoupling of CO2e emissions from economic growth of the industry from 2000 to 2020.

Dissertation (PhD(Agric))--Stellenbosch University, 2003.
ENGLISH ABSTRACT: The codling moth, Cydia pomonella (L.) has been a major pest of pome fruits since before the turn of the last century. However, despite its high economic profile little is known about the bionomics and . behaviour of this pest in apple orchards in South Africa, information required for the development of a sustainable integrated management programme. In field trials there was contingency between the time of year and the upper and lower half of the tree. First generation moths laid significantly more eggs in the bottom half of the tree while second and third generation moths laid significantly more eggs in the top half of the tree. The preferred oviposition sites on Granny Smith (GS) and Golden Delicious (GD) cultivars, in order of preference, were leaves, fruit and wood. More eggs were laid on the fruit ofGS spurs (35.6 %) than on those ofGD spurs (10.7 %). On fruit spurs there was a significant increase in the number of eggs on GD leaves and GS fruit over the season, whereas the number of eggs on GS leaves and GD fruit remained constant. On branches there was an increase in the number of eggs on GD and GS leaves, but not on the fruit or wood. The preferred oviposition site on the fruit was the fovea of the stalk insertion and the rounded cheek area surrounding the fovea. The distribution within different fruit bearing classes (1 - 4 fruit per spur) was random only for one fruit per spur, while on the other spur classes clustering occurred. In laboratory studies of the embryonic and immature stages there was a linear relationship between rate of development and constant temperatures of 15, 17,20,25 and 30·C ± l·C. The lower threshold temperatures for embryonic, larval and pupal development were 11.1, 7.9, 9.9°C respectively. The degree-days required to complete embryonic, larval and pupal development were 80.5, 345, and 279 respectively. The response of the different stages to constant temperatures was similar to that under fluctuating temperatures. At temperatures below 16°C or abouve 27°C moths did not mate and few eggs were laid. Moth longevity decreased with increasing temperature. There was seasonal variation in longevity and oviposition at constant and fluctuating temperatures. Summer adults produced significantly more eggs than spring adults at constant temperatures. At a constant temperature of2S·C and fluctuating temperatures there were five distinct larval instars. The similarity between the mean head capsule width and ranges for each instar reared on fruit of different stages of development at fluctuating temperatures indicates that fruit development and temperature have little influence on mean head capsule width. From sleeve-cage studies in the orchard there was no significant difference in the fecundity of spring and summer moths. In the beginning of October spring moths produced significantly fewer eggs than in November. Egg mortality increased from 8.2 %in spring to 21.2 %in summer. Failure of 1st instar larvae to penetrate the fruit ranged from 4.9 % to 19.5 %, while mortality oflarvae from egg hatch to emergence from the fruit ranged from 29.7 % to 42.9 %. Mortality of 5th instar larvae after emerging from the apples ranged from 0 % to 8.7 % and pupal mortality from 0 % to 3.5 %. On large 27-year old trees more overwintering larvaewere found on Golden Delicious (13.9) than on Granny Smith trees (5.7), with over 70 % oflarvae being found in pruning wounds on both cultivars. On small 7-year old Golden Delicious and Granny Smith trees the mean number oflarvae was 0.5 and 2.0 per tree. A combined mating disruption and insecticide control programme reduced codling moth resistant populations to levels requiring a minimum to no insecticide intervention for several seasons. The efficacy of a pheromone based strategy, number of pheromone treatments, number of dispenserslha and level of insecticide intervention required are strongly influenced by prevailing weather conditions. Fruit infestation in orchards under a mating disruption programme and under an insecticide programme were greater along the borders compared to the interior. The presence of horticultural mineral oil on the leaves and branches did not have a detrimental effect on oviposition nor was there any significant ovicidal effect. A significant ovicidal effect was obtained when applied after oviposition. In field trials, insecticides with lower levels of efficacy than the primary insecticide, azinphos-methyl, provided acceptable control when successfully incorporated into a spray programme which followed a policy of alternation of insecticides across generations. The least variation in the number of degree-days between biofix and first egg hatch of the spring flight was when the second trap catch (Biofix 2) was used as the biofix. A biofix based on the first evening when the temperature reached or exceeded 1TC at 18:00 after first trap catch also showed less variation than when the biofix was based on first trap catch. The mean number of degree-days accumulated between Biofix 2 and first egg hatch was found to be 139.1 ° D. The number of degreedays between the first and second flight biofixes varied between 531.2 and 488.87°D with a mean of 508.1°D.
AFRIKAANSE OPSOMMING: Kodlingmot (Cydia pomonella) is reeds sedert die vorige eeu 'n sleutelplaag van kemvrugte. Ten spyte van die hoë ekonomiese profiel, is daar min kennis betreffende die bionomie en gedrag van hierdie plaag in appelboorde in Suid-Afrika. Hierdie inligting is noodsaaklik vir die ontwikkeling van 'n volhoubare geïntegreerde bestuursprogram. Tydens veldproewe is 'n korrelasie tussen die tyd van die jaar en eierlegging in die boonste of onderste helfte van bome gevind. Eerste-generasie motte het betekenisvol meer eiers in die onderste helfte van die bome gelê, terwyl tweede- en derde-generasie motte meer eiers in die boonste helfte van die bome gelê het. In toenemende volgorde was die voorkeur eierleggingsposisies op Granny Smith (GS) en Golden Delicious (GD) appels die blare, vrugte en hout. Meer eiers is op vrugte van GS spore (35.6%) as op dié van GD spore (10.7%) gelê. Op vrugspore was daar 'n betekenisvolle toename in aantal eiers op GD blare en GS vrugte deur die seisoen, terwyl die getal eiers op GS blare en GD vrugte konstant gebly het. Op takke was daar 'n toename in aantal eiers op GD en GS blare, maar nie op vrugte of hout nie. Die voorkeur eierleggingsposisie op vrugte was die fovea van die steelaanhegting en die wang rondom die fovea. Die verspreiding tussen verskillende vrugdraende klasse (1 - 4 vrugte per spoor) was slegs in die een-Vrug-per-spoorklas ewekansig, terwyl daar in die ander spoorklasse groepering voorgekom het. In laboratoriumstudies van embrioniese en onvolwasse stadia is 'n lineêre verband tussen ontwikkelingskoers en konstante temperature van 15, 17,20,25 en 30°C±I°C gevind. Die onderste drempel-temperature vir embrioniese, larwale en papie-ontwikkeling was onderskeidelik II. 1°C, 7.f?C en 9.9°C. Graaddae benodig vir voltooiing van embrioniese, larwale en papie-ontwikkeling was onderskeidelik 80.5,345 en 279. Die respons van verskillende stadia by konstante temperature het ooreengestem met hul respons onder wisselende temperature. Motte het nie gepaar nie en min eiers is gelê by temperature onder 16°C of bo 27°C. Die lewensverwagting van motte het afgeneem met toename in temperatuur. Seisoenale variasie in . lewensverwagting en eierlegging het voorgekom by konstante sowel as wisselende temperature. By konstante temperature het somer-volwassenes betekenisvol meer eiers as lente-volwassenes geproduseer. By 'n konstante temperatuur van 25°C, sowel as by wisselende temperature, het vyf duidelik onderskeibare larwale instars voorgekom. Die ooreenkoms tussen die gemiddelde kopkapsulewydte en wydte-reeks vir elke instar wat op vrugte van verskillende stadiums van ontwikkeling by wisselende temperature geteel is, dui daarop dat vrugontwikkeling en temperatuur weinig invloed op gemiddelde kopkapsule-wydte het. Tydens mou-hok studies in die boord is geen betekenisvolle verskil in die fekunditeit van lente- en somer-motte waargeneem nie. Vroeg in Oktober het lente-motte betekenisvol meer eiers as in November geproduseer. Eiermortaliteit het van 8.2% in die lente tot 21.2% in die somer toegeneem. Faling van 1ste instar larwes om vrugte te penetreer het van 4.9% tot 19.5% gewissel, terwyl mortaliteit van larwes vanaf uitbroei tot uitkoms uit die vrug van 29.7% tot 42.9% gewissel het. Mortaliteit van Sde instar larwes na uitkoms uit die vrug het van 0% tot 8.7% gewissel, en papie-mortaliteit van 0% tot 3.5%. Op groot, 27-jaar oue bome is meer oorwinterende larwes op Golden Delicious (13.9) as op Granny Smith (5.7) gevind, en meer as 70% van die larwes op beide kultivars is op snoeiwonde gevind. Op klein, 7-jaar oue bome was die gemiddelde aantallarwes op Golden Delicious en Granny Smithbome 0.5 en 2.0 onderskeidelik. 'n Gekombineerde paringsontwrigting- en insekdoder beheerprogram het weerstandbiedende kodlingmot-populasies verminder tot 'n vlak waar minimum tot geen insekdoder-toedienings vir verskeie seisoene gemaak is. Die effektiwiteit van 'n feromoon-gebaseerde strategie, aantal feromoonbehandelings, aantal vrystellers/ha en vlak van insekdoder-toediening word sterk deur heersende weersomstandighede beïnvloed. Die rande het hoër vruginfestasie as die middel getoon in boorde onder paringsontwrigting sowel as boorde onder insekdoder-programme. Die teenwoordigheid van minerale olie op blare en takke het geen nadelige effek op eierlegging gehad nie en dit het geen betekenisvolle eierdodende effek gehad nie. Indien die olie ná eierlegging toegedien is, is daar wel 'n betekenisvolle eierdodende effek waargeneem. Tydens veldproewe het insekdoders met laer effektiwiteit as die primêre insekdoder, azinfos-metiel, aanvaarbare beheer verskaf indien dit suksesvol geïnkorporeer is in 'n spuitprogram deur 'n beleid van afwisseling van insekdoders oor generasies. Die kleinste variasie tussen die aantal graaddae tussen biofix en eerste uitbroei van eiers is gevind indien die tweede lokvalvangs as biofix gebruik is. 'n Biofix gebaseer op die eerste aand na die eerste lokval vangste wat die temperatuur 17°Cofhoër was teen 18:00, het ook 'n kleiner variasie getoon as die eerste lokvalvangs. Die aantal graaddae tussen die tweede en derde vlug biofix het tussen 531.2 en 488.87°D gewissel, met 'n gemiddelde van 508.1°D.

The impact of TAL Pro-long and certain other sucrose ester coatings on the development of six common post-harvest fungal rots of pome fruit was investigated. The preparations were not observed to be fungistatic but TAL Pro-long did diminish the incidence of fungal infections on conference pears held in cold storage. At higher temperatures, depending on the nature of the disease, the coatings were able to modify the spatial distribution and reduce the rate of spread of the lesions within apples (cvs 'Chiver's Delight', 'Cox's Orange Pippin' and 'Granny Smith's') and pears (predominantly cv. 'Conference'). In comparison to the rate of decay in non-coated fruit, TAL Pro-long had a greater effect on those rots caused by Botrytis cinerea Fr., Monilinia fructigena (Aberh. & Ruhl.) Honey and Rhizopus nigricans Lind. than those of Alternaria alternata Fr., M. laxa (Aberh. & Ruhl.) Honey and Penicillium expansum Link em. Thom. The efficacy of the treatments was attendant on the ability of the surface coatings to ameliorate the rate of fruit ripening and was much influenced by the composition and concentration of the preparations, the variety of the fruit, the timing of the applications (relative to the onset of ripening and the climacteric rise in ethylene), and the temperature to which the produce was subsequently exposed. Studies indicated that, in Conference pears, the profile of simple sugars and the activity of certain extracellular enzymes produced by M. fructigena and P. expansum were modified by TAL Pro-long. The changes in enzyme activity were not obviously correlated with the development of the rots but there was an apparent association between coating and the reduced availability of monosacharides and sucrose in the tissues of the host. The sucrose ester coatings accentuated the differential permeability of the fruit skin to gases leading to a rapid decline in oxygen and a rise in carbon dioxide. Experiments indicated that such modified gas environments were unlikely to prevent the growth of pathogens but that they did effect the production and action of ethylene. It is suggested that the internal gas atmospheres established within the fruit delayed the inactivation of hormonal 'senescence retardants' and thereby diminished the sensitivity of the tissues to ethylene with the result that the rate of ripening was reduced and the innate resistance mechanisms of the fruit were retained for an extended period.

Thesis (MScConsEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) (obscure mealybug), is a common and serious pest of apples and pears in South Africa. Consumer and regulatory pressure to produce commodities under sustainable and ecologically compatible conditions has rendered chemical control options increasingly limited. Information on the seasonal occurrence of pests is but one of the vital components of an effective and sustainable integrated pest management system needed for planning the initiation of monitoring and determining when damage can be expected. It is also important to identify which orchards are at risk of developing mealybug infestations while development of effective and early monitoring tools for mealybug populations will help growers in making decisions with regards to pest management and crop suitability for various markets. It is also essential to determine the presence and efficacy of naturally occurring biological control agents in orchards so as to ascertain the potential of biological control as a viable alternative in orchards. However, under the current integrated pest management protocol, it has been difficult to determine this, due to the sporadic and relatively low incidence of mealybug infestations in some orchards, or by simply relying on naturally occurring field populations of biocontrol agents. Knowledge of the environmental conditions under which P. viburni population levels may become destructive is also essential for timing the release of insectary reared natural enemies as well as understanding the population ecology of this pest and its natural enemies. Information was gathered regarding the seasonal phenology of P. viburni and its natural enemies in pome fruit orchards in the Western Cape Province during the 2007/08 and 2008/09 growing seasons. Seasonal population studies showed that P. viburni has multiple overlapping generations with all life stages present throughout the year. The highest orchard infestations occurred during the summer period until early winter (January to early June). This was followed by a decrease in population from late June to November, before another increase in December. Presence-absence sampling of mealybugs on the host plant revealed that woody parts of the tree, such as the trunk and old stems were the most preferred sites for mealybug habitation, due to the availability of protected refuge sites. Migration of mealybug populations to newer growth and the upper sections of the tree crown, such as the new stems, leaves and eventually the fruit, was observed from December throughout the summer period until the early winter in June. Fruit colonization in both apples and pears commenced in January, when the fruit had developed a size sufficient for P. viburni to penetrate and occupy spaces such as the fruit core, calyx and stem end. There was no evidence of P. viburni occurring beneath the soil surface or on the roots of host trees. Two natural enemies of mealybugs, namely Pseudaphycus maculipennis (Mercet) and Coccidoxenoides perminutus (Girault), were found to be active in apple and pear orchards in the Western Cape. However, the status of C. perminutus as a parasite of P. viburni still needs to be verified despite evidence of emergence from P. viburni mummies, which was not sufficient enough to suggest that it is a useful biological control agent. Seasonal abundance trends of the two natural enemies revealed that their lifecycle is synchronized with that of the host. However, there was no evidence of P. maculipennis activity in Ceres. No predators were found during the course of this study. The rate of P. viburni parasitism at harvest was 46.52%, with P. maculipennis and C. perminutus constituting 98.966% and 1.034% of the parasitoids recovered from mealybug mummies, respectively. Studies on the use of pheromone traps as early monitoring tools for P. viburni showed that there was a positive and significant relationship between the fruit infestation and number of P. viburni adult males caught in pheromone-baited traps (r2 = 0.454). The action threshold level was estimated to be 2.5 male P. viburni caught per trap per fortnight at an economic threshold of 2% fruit infestation.
AFRIKAANSE OPSOMMING: Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) (ligrooswitluis), is ‘n algemene en ernstige plaag van appels en pere in Suid-Afrika. Druk deur verbruikers en regulasies om kommoditeite onder volhoubare en ekologies verenigbare toestande te produseer het chemiese beheeropsies toenemend beperk. Inligting oor die seisoenale voorkoms van plae is een van die essensiële komponente van ‘n effektiewe en volhoubare geïntegreerde plaagbestuurprogram. Dit is in die aanvanklike beplanning van monitering en om te bepaal wanneer skade verwag kan word. Dit is ook belangrik om boorde vroegtydig te identifiseer wat die risiko het om witluisbesmettings te ontwikkel. Die ontwikkeling van effektiewe en vroeë moniteringstegnieke vir witluisbevolkings sal produsente help met besluitneming rakende plaagbestuur en die geskiktheid van gewasse vir verskeie markte. Dit is ook noodsaaklik om die teenwoordigheid en effektiwiteit van biologiese beheer agente wat natuurlik in boorde voorkom te bepaal ten einde die potensiaal van biologiese beheer as ‘n lewensvatbare alternatief vas te stel. Onder die huidige geïntegreerde plaagbestuurprotokol was dit egter moeilik om laasgenoemde te bepaal weens die sporadiese en relatiewe lae voorkoms van witluisbesmettings in sommige boorde of deur bloot staat te maak op die veldpopulasies van biologiese beheer agente wat natuurlik voorkom. Kennis van die omgewingstoestande waaronder P. viburni bevolkingsvlakke skadelik raak is ook noodsaaklik vir die beplanning van vrylating van biologiese beheer agente, asook om die bevolkingsekologie van hierdie plaag en sy natuurlike vyande te verstaan. Inligting oor die seisoenale fenologie van P. viburni en sy natuurlike vyande in sagtevrugte boorde in die Westelike Kaapprovinsie is gedurende die 2007/08 en 2008/09 groeiseisoene versamel. Seisoenale bevolkingstudies het getoon dat P. viburni verskeie oorvleuelende generasies het met alle stadia teenwoordig regdeur die jaar.

Total soluble solids (TSS) is a reliable indicator of melon eating quality, with a minimum standard of 10% recommended. The state of Australian melon production with respect to this quality criterion was considered within seasons, between growing districts and over seasons. It was concluded that improvement in agronomic practice and varietal selection is required to produce sweeter melons. The scientific literature addressing melon physiology and agronomy was summarised, as a background to the work that is required to improve melon production practices in Australia. The effect of source sink manipulation was assessed for commercially grown and glasshouse grown melon plants. The timing of fruit thinning, pollination scheduling, the application of a growth inhibitor and source biomass removal were assessed in relation to fruit growth and sugar accumulation. Results are interpreted against a model in which fruit rapidly increase in weight until about two weeks before harvest, with sugar accumulation continuing as fruit growth ceases. Thus treatment response is very dependant on timing of application. For example, fruit thinning at 25 days before harvest resulted in further fruit set and increased fruit weight but did not impact on fruit TSS (at 9.8%, control 9.3%), while thinning at 5 days before harvest resulted in a significant (Pless than 0.05) increase in fruit TSS (to 10.8%, control 9.3%) and no increase in fruit weight or number. A cost/ benefit analysis is presented, allowing an estimation of the increase in sale price required to sustain the implementation of fruit thinning. The effect of irrigation scheduling was also considered with respect to increasing melon yield and quality. To date, recommended practice has been to cause an irrigation deficit close to fruit harvest, with the intent of 'drying out' or 'stressing' the plant, to 'bring on' maturity and increase sugar accumulation. Irrigation trials showed that keeping plants stress-free close to harvest and during harvest, facilitated the production of sweeter fruit. The maintenance of a TSS grade standard using either batch based (destructive) sampling or (non-invasive) grading of individual fruit is discussed. On-line grading of individual fruit is possible using near infrared spectroscopy (NIR), but the applicability of the technique to melons has received little published attention. Tissue sampling strategy was optimised, in relation to the optical geometry used (in commercial operation in Australia), both in terms of the diameter and depth of sampled tissue. NIR calibration model performance was superior when based on the TSS of outer, rather than inner mesocarp tissue. However the linear relationship between outer and middle tissue TSS was strong (r2 = 0.8) in immature fruit, though less related in maturing fruit (r2 = 0.5). The effect of fruit storage (maturation/senescence) on calibration model performance was assessed. There was a negligible effect of fruit cold storage on calibration performance. Currently, the agronomist lacks a cost-effective tool to rapidly assess fruit TSS in the field. Design parameters for such a tool were established, and several optical front ends compared for rapid, though invasive, analysis. Further, for visualisation of the spatial distribution of tissue TSS within a melon fruit, a two-dimensional, or hyper-spectral NIR imaging system based on a low cost 8-bit charge coupled device (CCD) camera and filter arrangement, was designed and characterised.

Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: Codling moth, Cydia pomonella, is a worldwide pest and of major economic importance to the South African pome fruit industry. Sterile insect release is applied as a component of area-wide integrated pest management and includes the mass-rearing, sterilization and the release of the sterile insects. For sterile insect release, the improvements of rearing methods in terms of the quality of the diet ingredients and the economical aspect of the rearing method are examined. The effect of genetically modified maize meal, containing the Bacillus thuringiensis gene, in an artificial medium for codling moth rearing, is determined. The use of even a small amount of Bacillus thuringiensis resulted in larval mortality and prolonged development. These results are detrimental to a mass-rearing facility and must be considered by any rearing facility that uses genetically modified maize meal if the insect is sensitive to the gene. An alternative to maize meal in the artificial medium was tested and whole wheat flour was considered to be a suitable replacement. Agar agar is an expensive gelling agent used in the artificial medium. An alternative for agar agar (Kelcogel, Elastigel and carrageenen) is tested and the biological effect on codling moth is determined. Factors such as mortality, pupal and moth weight, longevity, fecundity and development time were used as quality parameters. Results showed that Elastigel was a suitable replacement for agar agar, with bigger pupae and moths, higher fecundity and increased longevity. The economical advantage of the replacement is a 40.91% reduction of the diet cost. The other gelling agents tested also gave acceptable results and can be considered if shortages of agar agar or Elastigel occur. A new method of mass-rearing codling moth larvae in a closed rearing system using large trays placed in a ventilated box is designed. This method is more cost and space effective as a smaller area is needed to rear a large number of moths. The risk of diet contamination is less because of the closed environment and more economical and effective air handling. This is the first report of its kind to describe the mass-rearing of codling moth in a closed environment and the risks involved in using genetically modified maize meal in an artificial diet for the codling moth. These results should be incorporated into existing mass-rearing facilities or taking into consideration when designing new mass-rearing facilities.
AFRIKAANSE OPSOMMING: Die kodlingmot, Cydia pomonella, is van ekonomiese belang vir die Suid-Afrikaanse kernvrugte bedryf. Die steriele insek tegniek word gebruik as ‘n komponent in area-wye geïntegreerde plaagbeheer en sluit in die massa-aanteel, sterilisering en vrylaat van steriele insekte. Vir die steriele insek tegniek is die verbetering van die massa-aanteel van die kodlingmot in terme van kwaliteit van die dieet en die ekonomiese aspek van die aanteel metode ondersoek. Die effek van genetiese gemanipuleerde mieliemeel wat die Bacillus thuringiensis geen bevat, in ‘n kunsmatige voedselmedium vir die aanteel van kodlingmot, is bepaal. Daar is gevind dat die gebruik van selfs ‘n klein persentasie Bacillus thuringiensis in die mieliemeel, mortaliteit en ‘n verlengde lewenssiklus in kodlingmot veroorsaak. Die gevolge is nadelig vir ‘n massa-aanteel fasiliteit en behoort in ag geneem te word vir enige insek wat op ‘n kunsmatige medium, wat mieliemeel bevat, geteel word, mits die insek sensitief is vir Bacillus thuringiensis. ‘n Alternatiewe bestanddeel vir mieliemeel, volkoringmeel, word aanbeveel. Agar agar is ‘n duur verdikkingsagent wat in kunsmatige mediums gebruik word. ‘n Alternatief vir agar agar (Kelcogel, Elastigel en carrageenen) is getoets en die biologiese effek op die kodlingmot is bepaal. Faktore soos mortaliteit, papie en mot gewig, langlewendheid, vrugbaarheid en lengte van lewenssiklus was gebruik as kwaliteit parameters. Resultate het getoon dat Elastigel ‘n geskikte plaasvevanger is van agar agar, met groter papies en motte, groter vrugbaarheid en langlewendheid. Die ekonomiese gevolg van die plaasvervanger, is ‘n vermindering van 40.91% van die dieetkoste. Die ander verdikkingagente wat is getoets is, het aanvaarbare resultate gelewer wat noodsaaklik is indien daar ‘n tekort van Elastigel of agar agar ontwikkel. ‘n Nuwe metode van massa-aanteel van kodlingmot larwes is bepaal. Die metode behels ‘n geslote sisteem, waar groter aanteel bakke in ‘n geslote, geventileerde boks geplaas word. Die metode is koste en spasie effektief en ‘n kleiner area word benodig om ‘n groter aantal motte te lewer. Die risiko van kontaminasie van die dieet word verminder as gevolg van die geslote sisteem wat gebruik word en meer ekonomiese en effektiewe lugversorging word gebruik. Hierdie is die eerste verslag van sy soort wat die massa-aanteel van kodlingmot in ‘n geslote sisteem beskryf en wat die risiko aandui van geneties gemanipuleerde mieliemeel in ‘n kunsmatige medium vir die kodlingmot. Hierdie resultate behoort in ag geneem te word vir reeds bestaande massa-aanteel fasiliteite of met die ontwerp van nuwe massa-aanteel fasiliteite.

Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia
Brown spot of pear, associated to Pleospora allii/Stemphylium vesicarium, is economically important in pear production in Europe and was detected, in 1996, in Portugal. The causal agent is known to share similar morphological characteristics with other fungi in the genus, namely S. botryosum known as a storage fungus, making the identification between them quite difficult. With the aim to contribute for a better knowledge of brown spot in pears, the pathogens involved in this disease and its presence in other fruit trees, we studied, from 30 Stemphylium monosporics isolates obtained from apples and pear fruits, and pears leaves, from Portugal, the optimal grow temperature, cultural, morphologic and biometric characteristics from anamorphs and/or teleomorphs, the time required for ascospore prodution and phylogenetic relationships, inferred from ITS and gpd sequence data. The optimum growth temperature stood between 22.5º C and 27.5º C, the ratio between length and width ranged from 1.38 to 2.38. The number of days until mature ascospores were produced ranged between 10 and 54 days. The gpd fragments of 28 isolates clustered with S. vesicarium from NCBI bank and the whole data allowed to identify 29 isolates as S. vesicarium

Les propriétés mécaniques du péricarpe de la pomme dépendent d'une multitude de facteurs. Sont impliqués la matière sèche, répartie entre fraction insoluble (parois) et fraction soluble, l'état de l'eau et sa répartition au sein de la cellule, la fraction d'air entre les cellules, et leur taille et organisation. L'état de l'eau et sa répartition n'ont été que peu étudiés et l'IRM quantitative est un outil de choix pour réaliser ces mesures de façon non-destructive. Nous avons de façon originale exploité le signal IRM multi-exponentiel de relaxation du fruit pour en extraire le signal de différentes fractions aqueuses. Etudier les variations d'amplitude et de temps de relaxation de ces fractions dans des fruits de calibre variable a permis de caractériser l'hétérogénéité du fruit et l'influence de la taille des cellules sur le signal IRM. Une approche multi-instrumentale appliquée au parenchyme durant un stockage au froid a ensuite permis de mettre en regard ses propriétés viscoélastiques (analyse mécanique dynamique) avec sa répartition hydrique et sa porosité (IRM) et la taille, la forme (macro-vision) et la composition (dosage des sucres solubles, hémicelluloses et pectines pariétales) de ses cellules. Enfin, le signal IRM a été étudié sur l'ensemble des tissus du fruit à 1 mois et 6 mois de stockage. Ce travail a permis de démontrer l'intérêt de l'approche IRM pour décrire l'hétérogénéité du fruit sur des critères d'état de l'eau et de répartition de l'eau et de la porosité, de préciser certains mécanismes impliqués dans la relaxation RMN et de hiérarchiser les différents paramètres de structure et de composition impliqués dans les propriétés mécaniques des tissus
Mechanical properties of the pericarp of apple fruit are defined by multiple factors. Dry matter, as an insoluble fraction (cell wall) and a soluble fraction, water status and distribution within cell and tissues, the fraction of air between the cells and their size and organization influence the mechanical behavior of the tissue. Quantitative MRI is an interesting tool as it can non-destructively measure water status and distribution, which have seldom been studied. An original approach was applied by measuring the MRI multi-exponential relaxation signal of the fruit to extract the signal of different water pools. Studying the variations in amplitude and relaxation times of these fractions in fruit of different calibers allowed characterizing the heterogeneity of the fruit and the influence of cell size on MRI signal. A multi-instrumental approach applied to the parenchyma during cold storage then allowed comparing its viscoelastic properties (dynamic mechanical analysis) to its water distribution and its porosity (MRI) and the size, shape (macro-vision) and chemical composition (dosage of soluble sugars, cell wall hemicellulose and pectin) of its cells. Finally, the MRI signal of the tissues of whole fruit was studied at 1 and 6 month's storage. This study demonstrated the interest of MRI approach for characterizing the heterogeneity of the tissue according to water status and distribution and porosity. A better undestanding of some mechanisms implied in the NMR relaxation and of the relative influence of the structural and composition parameters on mechanical properties of the tissues was achieved

Les tests d'impact sur une surface metallique plane et rigide ont permis de simuler et d'etudier les phenomenes d'impact rencontres lors de la manutention des fruits (pommes). L'enregistrement des spectres d'impact (force-temps) est realise par l'intermediaire d'un capteur de force relie a un oscilloscope numerique connecte a un micro-ordinateur. Plusieurs parametres d'impact sont deduits de ces spectres. Le brunissement consecutif a l'endommagement cause par l'impact est quantifie par le releve de son diametre et de sa profondeur. La sensibilite aux meurtrissures est suivie en cours de conservation du fruit au froid. L'etat physique du fruit est evalue au moyen de tests penetrometriques et acoustiques et la fermete est quantifiee sous forme de coefficients d'elasticite. Les comportements au cours de l'impact et les caracteristiques de brunissement sont etudies en fonction des variations des energies d'impact. Le mecanisme de brunissement est simule en utilisant le methode des elements finis. La theorie de la plasticite est appliquee a l'estimation du volume bruni a partir de la contrainte d'impact, d'impact instantanee ou penetrometrique et a l'evaluation de l'energie absorbee durant l'impact. Les equations de hertz relatives a la theorie de l'elasticite sont utilisees pour l'etablissement de formules predictives du volume de brunissement. Une equation est proposee pour la prevision du volume lese en fonction de la hauteur de chute et de la duree de conservation.

La pomme est un des fruits les plus consommés au monde.Le développement d’une texture farineuse est un caractère rédhibitoire pour les consommateurs et pour la profession.La farinosité renvoie à une texture sèche et granuleuse en bouche qui se développe en cours de conservation. Malgré son importance, les connaissances sur les processusmoléculaires mis en jeu restent très parcellaires et son évaluation ne repose jusqu’à ce jour que sur des analyses sensorielles. Or, comprendre les mécanismes moléculairessous-jacents à la farinosité est nécessaire à l’amélioration de la qualité du fruit. Cette étude constitue la première étude transcriptomique globale de la farinosité. Une première étude multi-échelle,intégrant des données transcriptomiques, biochimiques et phénotypiques a été réalisée sur six hybrides issus d’un même croisement et présentant des textures contrastées pour lafarinosité.Cette étude a permis d’identifi er un gène marqueur précoce de la farinosité, MdPME2, codant pour une pectine méthylestérase. Par la suite, une analyse transcriptomiqueélargie à 34 variétés a permis de mettre en évidence un rôle clé de la voie du jasmonate dans la régulation de la maturation. Les jasmonates semblent orchestrer la voie de biosynthèse de l’éthylène et le stress oxydatif, contribuant ainsi à retarder la mise en place de la farinosité. Par ailleurs, afin de quantifier la farinosité autrement que via des analyses sensorielles, un nouveau test a été développé et permettra la validation fonctionnelle de ces résultats. Finalement, ce travail de thèse permet de proposer un
Apple fruit is one of the most consumed fruits in the world. Apple mealiness is an important textural deterioration which occurs during storage. This phenotype refers to a dry andgrainy sensory perception during mastication. Despite its significance, this phenotype is still rather poorly characterized, the few available results mostly depending on sensory analyses. Understanding the molecular mechanisms involved in the development of this unwanted character is essential for the improvement of fruit quality and fruit production.The work presented here is focused on the identification of key genes associated with apple mealiness through global transcriptome analyses. A first multiscale analysis combining transcriptomic, biochemical and phenotypic analyses was performed on pairs of individuals displayingcontrasted phenotypes for mealiness.This analysis led us to the identifi cation of one pectin methylesterase gene, MdPME2, which appears as an early molecular marker of mealiness in this genetic background. Next, a transcriptome analysis enlarged to 34 cultivars allowed the identification of the jasmonate hormonal pathway as a key driver of apple fruits ripening. By regulating ethylene and oxidative stress pathways, jasmonates appear as a fi ne-tuning regulator onthe postponement of apple mealiness. In addition, a new quantitative test of mealiness has also been developed to allow the validation of this model by means of pharmacological approaches. The main outcome of this work is to propose a new molecular model to explain apple mealiness development. This work shed

La couleur, la fermeté, la saveur, ou l’aptitude à la conservation, sont les principaux critères de qualité qui déterminent le choix du consommateur, les procédés de transformation et la stabilité des fruits charnus. Ces critères dépendent des mécanismes déterminants la qualité des productions, faisant intervenir les ions métalliques, les composés phénoliques et les parois cellulaires. Pour appréhender ces mécanismes, les travaux ont été réalisés sur deux variétés de pommes à cidre et étendus aux variétés de raisins de cuve. Le développement de méthodes de cryo-microscopie associées à la fluorescence X et UV a permis l’identification et la distribution tissulaire des ions métalliques et des composés phénoliques. Les métaux de transition et les flavanols sont retrouvés majoritairement dans la cuticule alors que le calcium, le magnésium et les pigments phénoliques sont co-localisés dans les couches sous-cuticulaires. Une distribution homogène du potassium est observée de la couche sous-cuticulaire au cortex externe, zones riches en acides phénoliques. Parmi ces acides, les acides hydroxycinnamiques sont potentiellement estérifiés dans les parois cellulaires. L’impact de ces composés sur la qualité des fruits lors de leur consommation ou transformation a été abordé par l’étude des interactions entre les ions métalliques, la pectine des parois cellulaires et les composés phénoliques en présence de peroxyde d’hydrogène. L’ensemble des résultats : distribution des ions métalliques et composés phénoliques, ainsi que les interactions et les mécanismes réactionnels possibles est résumé dans un modèle conceptuel qui servira de base pour de futurs travaux visant à un meilleur contrôle des propriétés organoleptiques des fruits frais et transformés
Colour, firmness, taste and long storage ability, are the main quality parameters that define consumer choice, processing and shelf-life of fleshy fruits. These quality criteria rely on physiological and physicochemical mechanisms that involve metallic ions, phenolic compounds and cell wall. To better understand these mechanisms, the thesis study was realised on two cider apples varieties and extended to wine grapes. The development of cryo-microscopy methods associated to X-ray and deep UV fluorescence highlighted the identification and distribution at the tissue scale of metallic ions and phenolic compounds. Transition metals and flavanols were mostly found in the cuticle while calcium, magnesium and phenolic pigments were co-localised in the sub-cuticle tissue layers. A homogeneous distribution of potassium was observed from the sub-cuticle to the outer cortex cell layers, a region that is rich in phenolic acids. Among these acids, hydroxycinnamic acids were found to be potentially esterified within cell wall. The impact of these compounds on the quality of fruit during consumption or processing was considered by studying the interactions between metal ions, cell wall pectin and phenolic compounds in the presence of hydrogen peroxide. All results: distribution of metal ions and phenolic compounds, as well as possible interactions and mechanisms of reaction, are summarized in a conceptual model that will serve as a basis for future work aiming at better controlling the organoleptic properties of fresh and processed fruit

L'évaporation osmotique est une nouvelle opération membranaire dont le but est la concentration de solutions aqueuses à température ambiante et à pression atmosphérique. Le liquide à concentrer (phase d'alimentation) est séparé d'une solution salée très concentrée (phase réceptrice) par l'intermédiaire d'une fine membrane microporeuse hydrophobe. Le moteur du transfert de vapeur d'eau de la phase d'alimentation vers la phase réceptrice est un gradient de pression de vapeur d'eau dû à la différence de pression osmotique entre les deux liquides de part et d'autre de la membrane. Une synthèse bibliographique permet de situer l'évaporation osmotique par rapport aux autres contacteurs à membrane et notamment, par rapport à la distillation membranaire. L'étude théorique montre que dans des conditions normales d'utilisation, le flux de vapeur s'exprimera de façon différente selon la valeur du rapport du libre parcours moyen des molécules à la dimension de pore : selon les cas, la dimension de pore influera ou non sur le flux de vapeur transférée. Par la suite, une étude du procédé en cellule de diffusion a été menée. Les influences sur le flux de la pression osmotique de la phase réceptrice, des vitesses d'agitation des solutions, de la température ainsi que celles de l'épaisseur et de la dimension des pores de la membrane ont été évaluées. Les résultats de cette étude paramétrique ont ensuite été utilisés pour vérifier la validité du modèle de transport, évaluer les résistances au transport dues à la membrane et à la couche limite de concentration dans la phase réceptrice et enfin pour modéliser le procédé en cellule agitée (régime non laminaire) par l'établissement d'une expression reliant les trois nombres adimensionnels Reynolds, Schmidt et Sherwood. L'étude en cellule agitée a été complétée par une évaluation du rôle joué par la présence d'air dans les pores et par une application à la concentration de solutions à fortes teneurs en glucose. La dernière partie du travail concerne des essais pilotes sur du jus de pomme. Elle a montré la possibilité de concentrer ce jus de fruit jusqu'à 630 g/I. Dans la perspective d'une application industrielle, un schéma type d'installation combinant osmose inverse et évaporation osmotique a été proposé et les consommations énergétiques estimées.

L'accumulation des formes libres et liees de l'acc (amino-cyclopropane carboxylique acide) pose le probleme des mecanismes enzymatiques impliques tels que: efe (enzyme formant l'ethylene), acc synthetase et mabonyl-acc transferase. L'etude de tissus excises maintenus en survie sur milieu gelose contenant un inhibiteur tel que: le cordycepine, le cycloheximide et le cobalt ont permis de mettre en evidence certains mecanismes de regulation des emissions ethyleniques

Le jus cellulaire du kiwi (actinidia chinensis) est particulierement riche en vesicules membranaires, comparables a des protoplastes ou des vacuoles libres, obtenues sans traitements enzymatique ni chimique. En realite, ces structures sont essentiellement issues de la rupture puis de la revesiculisation du tonoplaste limitant les travees cytoplasmiques des cellules. La fragmentation des vacuoles, in situ, conduit le tonoplaste a se refermer aussi bien sur le suc vacuolaire que sur le cytoplasme des travees, ce qui implique une orientation differente de sa face interne, vis-a-vis du milieu exterieur. L'approche electrophysiologique chez les vesicules ou le tonoplaste garde son orientation initiale, met en evidence leur polarisation positive, a l'instar des protoplastes et des vacuoles isolees. Le changement de l'orientation du tonoplaste vis-a-vis du milieu inverse le gradient electrique transtonoplastique qui devient negatif. Les caracteristiques thermodynamiques du transport de k**(+) et h**(+) a travers le tonoplaste (inverse ou non) des vesicules des fruits conserves (variete hayward) montrent que les potentiels mesures (negatifs ou positifs) sont essentiellement d'origine diffusive. Neanmoins, chez les vesicules cytoplasmiques provenant des fruits frais (variete deliciosa), une faible composante electrogene associee au fonctionnement de la pompe a h**(+) (mg-atpase tonoplastique) n'est pas exclue

Des vignes de muscat d'alexandrie et des pommiers de golden delicious ont subi des traitements de flusilazole et de triforine, deux inhibiteurs de la biosynthese de l'ergosterol (ibe), pendant 2 ans. Afin de verifier les effets de tels traitements sur la composante aromatique des baies de raisin et des pommes, les composes libres et lies ont ete extraits et separes sur amberlite xad-2 et analyses par chromatographie en phase gazeuse couplee a la spectrometrie de masse. Les fractions libres et liees des vins et des jus de pomme correspondants ont ete egalement analysees. Il en resulte une modification dans la composition des fractions libres et liees, bien qu'aucun effet significatif n'ait ete observe sur la maturite des fruits traites. Les resultats obtenus sur les composes glycosiles suggerent que ces ibe peuvent agir sur les voies de glycosilation au sein de la plante. Dans les vins traites, les concentrations en aromes varietaux, fermentaires et prefermentaires ont ete modifiees et un mecanisme de regulation pour la synthese des sterols dans la levure mettant en jeu les monoterpenes peut etre envisage. D'autre part, des analyses de residus sur fruits et produits transformes, utilisant la chromatographie en phase en gazeuse equipee de detecteurs specifiques azote-phosphore (npd) ou a capture d'electrons (ecd), ont ete realisees.

Les caractéristiques sensorielles peuvent être mesurées par des méthodes descriptives d'évaluation sensorielle, parmi lesquelles le profil conventionnel. Les résultats sensoriels de profil présentent une forte variabilité, due, d'une part aux différences entre les sujets du panel, et d'autre part à la variabilité intra-lot, et notamment aux différences existant entre les individus d'un échantillon. À ce jour, la variabilité des sujets est prise en compte et les méthodologies de collecte et d'analyse des données ont été adaptées dans ce but. Néanmoins, la variabilité intra-lot n'a pas été abordée, malgré le challenge qu'elle représente. Avec pour produit modèle la pomme, ce travail de thèse aborde la problématique de la variabilité intra-lot sous deux angles : la mesure de la variabilité et la réduction de la variabilité, dans le but d'obtenir une mesure sensorielle plus fiable. Premièrement, la capacité de discrimination du panel a été observée entre les variétés étudiées et entre les fruits de chaque variété, identifiés comme différents selon une mesure instrumentale. Deuxièmement, afin de prendre en compte la variabilité intra-lot, le modèle d'analyse de la variance classiquement utilisé en évaluation sensorielle a été adapté avec l'ajout d'un facteur fruit hiérarchisé au facteur variété. Cette adaptation implique le partage de chaque fruit par plusieurs sujets. L'application de ce modèle a démontré l'importance de la variabilité intra-lot et l'importance du choix du modèle pour obtenir des résultats plus pertinents. De plus, le modèle d'analyse de la variance déterminé a été adapté afin de distinguer désaccord pur entre les sujets et différences de dispersion. Enfin, une réduction de la variabilité effective est obtenue par le partage des fruits ou par une homogénéisation instrumentale, cette dernière étant dépendante de la variété et de la mesure choisie. Les résultats de ce travail apportent des clés méthodologiques pour l'obtention de résultats fiables dans la cadre de l'évaluation sensorielle de produits variables.

La regulation de la biosynthese d'ethylene autocatalytique a ete etudiee, a 20c, lors de la maturation de pommes (malus domestica borkh. Cv. Granny smith) et de bananes (musa cavendishii lamb. ) apres recolte. Le co#2 (20%) inhibe le developpement de la crise climacterique de production ethylenique de la pomme mais non de la banane. Le co#2 (20%) n'a pas d'effet sur la teneur en acc libre de la pomme mais stimule la malonyltransferase et inhibe l'efe. Ces effets ne se retrouvent pas chez la banane. La synthese de l'efe de pommes preclimacteriques est stimulee par l'ethylene (10 l. L##1 pendant 40 h). Le co#2 (20%) s'oppose a cette stimulation mais il promeut l'activite de l'efe. L'action des ions ca#2#+ (1, 10, 100 mm) sur la production ethylenique et les teneurs en acc libre et conjugue a ete etudiee sur des echantillons de parenchyme de pommes climacteriques. La production d'ethylene basale et acc-dependante (2 mm) est fortement reduite par un effet apoplastique de 100 mm ca#2#+. L'inhibition de la production d'ethylene basale est associee a une augmentation de la teneur en acc total ce qui suggere que l'efe est localisee dans la membrane plasmique. Les ions ca#2#+ (1 mm) n'ont pas d'effet sur la production d'ethylene acc-dependante mais stimulent la production d'ethylene basale alors que les teneurs en acc decroissent. Ainsi, les influx d'ions ca#2#+ pourraient stimuler la translocation de l'acc endogene de ses compartiments de synthese et/ou de stockage, vers le ou les sites reactifs de la membrane plasmique

Les purées de fruits sont considérées ici comme des dispersions concentrées de particules végétales déformables et insolubles dans une phase continue aqueuse ou sérum riche en sucre et contenant des pectines solubles. La phase dispersée est constituée de cellules ou d'amas de cellules de parenchyme dont les parois insolubles ne représentent qu'une très faible masse (un peu plus de 1 % p/p) dispersées dans un sérum dont elle sont remplies. La constitution et les propriétés rhéologiques des purées vont dépendre de plusieurs facteurs internes tels que la variété de fruit et l'état de maturité et de facteurs externes tels que les paramètres liées au procédé de transformation (traitement mécanique et thermique). Par ailleurs, la texture est l'un des principaux attributs de qualité des purées et constitue à ce titre une source potentielle importante dans le développement de produits nouveaux. L'objectif général de ce travail a été de mieux comprendre les relations entre les propriétés rhéologiques, structurales et sensorielles des purées de pomme dans la perspective d'identifier des leviers d'action pour le pilotage « à façon » de la texture des produits. La stratégie de recherche a consisté à réaliser l'ensemble de l'étude à partir d'une même lot d'une purée issue d'une seule variété de pomme : Golden Delicious et à identifier les axes majeurs permettant de créer des structures et textures variées. Les trois paramètres structuraux qui ont été modifiés sont : la concentration en parois cellulaires (liée à la quantité de particules de pulpe), la taille des particules et la viscosité de la phase continue. Une technique de séparation - reconstitution couplée à un traitement de broyage ainsi que l'augmentation de la viscosité du sérum ont permis d'obtenir une large gamme de textures et de structures. La construction de deux plans expérimentaux a permis de maîtriser la préparation des produits pour l'étude des relations entre la structure, la rhéologie et la texture des purées. La caractérisation physique et sensorielle a mis en évidence l'importance des paramètres structuraux sur le comportement rhéologique et la perception de la texture des purées. Ainsi la concentration en particules a un effet de premier ordre, suivi par la granulométrie et la viscosité du sérum. L'augmentation de la teneur en particules se traduit directement au niveau de l'état d'encombrement du milieu qui dépend de leur taille. Un traitement mécanique entraîne la séparation des amas des cellules de parenchyme en cellules individualisées, ce changement de structure implique des modifications marquées de propriétés. La caractérisation rhéologique et structurale a permis d'établir des modèles rhéologiques et de mieux comprendre le comportement, l'état et le rôle des particules (molles et déformables) sur la structuration du milieu ainsi que le volume occupé par celles-ci. Cette approche a été complétée et validée par l'observation des dispersions par différentes techniques microscopiques. Les différents régimes de concentration, du régime dilué à l'état d'encombrement et de compaction du régime concentrée des purées ont pu être mis en évidence. Les deux axes principaux qui suffisent à décrire la texture sensorielle d'une purée sont la « consistance » et la « granulosité ». La viscosité de la phase continue a un impact sur la perception de la « granulosité » comme sur la cohésion du réseau particulaire. Les résultats montrent que la texture des dispersions végétales peut être « pilotée » à partir de la maîtrise de quelques grandeurs clés : la concentration en parois cellulaires (pulpe) et la granulométrie des particules complété par la viscosité de la phase continue. De grandes possibilités d'innovation sont ouvertes en jouant sur ces leviers notamment à partir des possibilités offertes au niveau des paramètres du procédé de fabrication
Fruit purees are considered as concentrated dispersions of deformable and insoluble particles in a continuous phase or serum rich in water, sugar and soluble pectin. The dispersed phase consists of cells or cell clusters of parenchyma tissue and the insoluble cell wall material dispersed in the serum represents a very low weight (~ 1% w/w). The structure and the rheological properties of purees will depend on many internal factors such as the variety and ripeness of the fruit and external factors occurring during the processing (mechanical and thermal treatment). Texture is a key quality attribute of purees and thus constitutes an important potential source for new product development. The main objective of this study was to better understand the relationship between the rheological, structural and sensory properties of apple puree, in order to pilot and control the texture of the products. The study was performed with a single batch of apple puree prepared industrially from fresh mature Golden Delicious. In order to create purees with varied structure and texture, three structural parameters were identified and modified: the cell walls concentration (related to the amount of pulp), the particle size and the viscosity of the continuous phase. A separation-reconstitution strategy joined to a grinding step and the modification of the serum viscosity allowed us to obtain a wide range of products with different structures and textures. The construction of two experimental designs made it possible the controlled preparation of the products so as to study the relatioins between structure, rheology and texture of the apple puree. Physical and sensory characterization highlighted the importance of structural parameters on the rheological behaviour and perception of the texture of the puree. Thus, the concentration of particles is the main parameter influencing these properties, followed by the particle size and the serum viscosity. The increase in particle content translates directly at the “overcrowding” that also depends on the particle size. Mechanical treatment leads to the separation of clusters of parenchyma cells in to individual cells; this change in structure involves marked changes of properties. Rheological and structural characterization made it possible the generation of rheological models and the better understanding of the behaviour, the state and the role of particles (soft and deformable) on the structure of the medium and the volume occupied by them. This approach has been completed and validated by the observation of dispersions by various microscopic techniques. The different regimes of concentration were identified. Texture perception of apple puree can be described basically by their “consistency” and their “graininess”. The viscosity of the continuous phase has an impact on the perception of “graininess” and in the cohesion of the particle network. Our results show that the texture of plant food dispersions can be “mastered” by controlling a few selected key parameters: the concentration of cell walls (pulp) and particle size, completed by the viscosity of the continuous phase. High possibilities for innovation are opened by playing on these parameters that can be modified during the processing

La carpocapsa [Cydia pomonella (L.) (Lepidoptera: Tortricidae)] és una de les plagues més importants dels fruiters de llavor (pereres, pomeres i codonyers) i dels noguers. El seu control és crític per a assolir una producció sostenible i amb qualitat per a l’exportació. La implementació de programes de control d’abast regional de grans àrees ha demostrat ser una estratègia molt efectiva que permet assolir molt bons resultats de control amb nivell de danys baixos i una reducció important en l’ús d’insecticides. En aquestos programes, la recollida, registre i flux de la informació per a la presa de decisions és un factor crític, essent necessari disposar de metodologies fiables des del punt de vista biològic i sostenible, des de l’econòmic. El recompte de les poblacions és un factor clau per a determinar el risc d’atac de la carpocapsa i prendre decisions de control. En aquest context s’avaluaren diferents aspectes de la taxonomia i el monitoreig de C. pomonella, com un caràcter per a la ràpida diferenciació entre mascles i femelles, el comportament i l’eficàcia d’un nou atraient per a l’estimació de les seves poblacions, l’ús de la geoestadística i els sistemes d’informació geogràfica per a la interpretació i el maneig de grans quantitats de dades de captura en trampes, l’efecte del vent en la distribució espacial dels adults i finalment, es proposa un sistema de vigilància d’abast nacional. un sistema de vigilancia a nivel regional. Es determinà que la taca negra present en la part inferior del primer parell d’ales dels mascles de C. pomonella és un caràcter sexual secundari fiable per a la diferenciació de mascles i de femelles capturats en trampes esquerades amb cairomona. Les trampes esquerades amb feromona més cairomona, són més atractives pels mascles i les femelles de carpocapsa que els esquers de cairomona sola i un 50% més atractius pels mascles que els esquers de 1 o 10 mg de feromona, en àrees tractades amb la tècnica de confusió sexual. La geoestadística pot ser una eina valuosa per a avaluar la distribució espacial de carpocapsa en aquestos programes de control i per a implementar models que considerin la delimitació de zones de risc pel control de plagues. L’activitat de vol de carpocapsa durant el mes de novembre (vol de la generació hivernant) té lloc quan la temperatura supera els 15°C i entre les 18:30 i les 02:00 h. No es detectà una influència significativa del vent durant el període esmentat en la distribució espacial de la plaga, per la qual cosa no es recomana una distribució de las trampes amb una separació diferencial segons la direcció. Es determinà que una separació de 200 m entre trampes ofereix informació fiable per la finalitat de vigilància fitosanitaria, amb una reducció propera al 60% en el nombre de trampes en relació a la separació de 100 m actualment en ús. Aquesta separació permetrà, a més, la disminució del cost del sistema de vigilància i monitoreig. En resum, s’avaluaren i desenvoluparen metodologies i eines que faciliten i tornen més eficient el monitoreig i el procés de presa de decisions en el control de C. pomonella en programes de grans àrees tractades amb la tècnica de confusión sexual.
La carpocapsa [Cydia pomonella (L.) (Lepidoptera: Tortricidae)] es una de las plagas principales de los frutales de pepita (peras, manzanas y membrillos) y nogales. Su control es crítico para lograr una producción sustentable y con calidad de exportación. La implementación de programas de control a nivel regional o de grandes áreas ha probado ser una estrategia altamente efectiva que permite lograr muy buenos resultados de control con bajos niveles de daño y una sustancial reducción en el uso de insecticidas. En estos programas, la colecta, registro y flujo de información para la toma de decisiones es un factor crítico, siendo necesario contar con metodologías confiables desde el punto de vista biológico y sustentables desde lo económico. El monitoreo de las poblaciones es un factor clave para determinar el riesgo de ataque de la carpocapsa y tomar decisiones de control. En este contexto se evaluaron diferentes aspectos de la taxonomía y el monitoreo de C. pomonella, como un caracter para la rápida diferenciación de machos y hembras, el comportamiento y eficacia de un nuevo atractivo para su monitoreo, el uso de la geoestadística y los sistemas de información geográfica para la interpretación y manejo de grandes cantidades de datos de captura en trampas, el efecto del viento en la distribución espacial de los adultos y finalmente, se propuso un sistema de vigilancia a nivel regional. Se determinó que la mancha negra presente en la parte inferior del primer par de alas de los machos de C. pomonella es un caracter sexual secundario confiable para la diferenciación de machos y hembras de la especie capturados en trampas que contienen cebos con cairomona. Las trampas cebadas con feromona mas cairomona, son mas atractivas para los machos y hembras de la carpocapsa que los cebos de cairomona sola y un 50% mas atractivas para los machos que los cebos con 1 o 10 mg de feromona, en áreas tratadas con la técnica de confusión sexual. La geoestadística puede ser una herramienta valiosa para evaluar la distribución espacial de la carpocapsa en éstos programas de control e implementar modelos que consideren la delimitación de zonas de riesgo parael control de plagas. La actividad de vuelo de la carpocapsa durante el mes de noviembre (vuelo de la generación invernante) ocurre cuando la temperatura supera los 15°C y entre las 18:30 y las 02:00 h. No se detectó una influencia significativa del viento durante el período mencionado en la distribución espacial de la plaga, por lo que no se recomienda una distribución de las trampas con un distanciamiento diferencial según la dirección considerada. Se determinó que una grilla de 200 m entre trampas ofrece información confiable para los fines de vigilancia fitosanitaria, con una reducción cercana al 60% en el número de trampas respecto a la grilla actualmente en uso de 100 m. Esta grilla además permitirá la disminución del costo del sistema de vigilancia y monitoreo. En resumen, se evaluaron y desarrollaron metodologías y herramientas que facilitan y tornan más eficiente el monitoreo y el proceso de toma de decisiones en el control de C. pomonella en programas de grandes áreas tratadas con la técnica de la confusión sexual.
The codling moth [Cydia pomonella (L.) (Lepidoptera: Tortricidae)] is one of the main pest attacking pome fruits (apples, pears, and quince) and walnuts. Its control is critical in order to obtain a sustainable production and exportable fresh fruit. The implementation of control strategies like areawide programs has proven to be very effective, allowing for a substantial reduction on damaged fruits and on the use of insecticides. Collection, registration and delivery of the information needed for the decision-making process, is a critical factor in these programs, being necessary to use proved and reliable biological and economically sustainable methodologies. Population monitoring is a key factor in order to assess the risk of attack of the codling moth and to decide the application of a control measure. Under this scenario, different aspects of C. pomonella taxonomy and biology were evaluated as long with new analytical tools. Among them, a sexual character for the quick differentiation of sexes, the efficacy of a new lure, the use of geostatistical analysis and Geographical Information Systems aimed to the manage bulk data of trap capture, the effect of the wind on the spatial distribution of adults, and finally a proposal of a regional surveillance system for the pest. As a result it was found that the black spot in the inner side of the forewings of males of C. pomonella is a reliable character for the differentiation of the sexes when they are trapped with lures containing kairomone. Traps lured with codlemone plus kairomone were more attractive to males and females of the codling moth than lures with kairomone alone, and 50% more attractive for males than lures containing 1 or 10 mg of codlemone, when used in orchards permeated with pheromones as a control measure. Geostatistical analysis could be a very valuable tool in order to evaluate de spatial distribution of codling moth in area-wide programs and to implement control strategies with the delimitation of riskareas of action. Adult flight activity during November (peak of overwinter generation flight) takes place when temperatures are above 15°C and from 18:30 to 2:00 h. No significant effect of the wind direction on the spatialdistribution of the pest was observed during this time of the year. In consequence, trap distance in different directions do not need to be modified. A grid with traps set at 200 m from each other, provides reliable information in order to keep an efficient phytosanitary surveillance program. The reduction of almost 60% of the number of traps used today, allows for a marked reduction of monitoring costs. In summary, several methodologies and tools were evaluated with the aim to make more simple and efficient the monitoring and control decision of C. pomonella in area-wide programs treated with mating disruption.

Dans le séchage des fruits et légumes, beaucoup de questions non résolues subsistent. Le «Swell-drying» est un procédé de séchage couplant une étape de déshydratation par air chaud à la texturation par Détente Instantanée Contrôlée (DIC). Dans le cadre de ce travail de recherche, la carotte et la pomme sont utilisées comme aliment modèle pour le traitement de la plupart des végétaux. La littérature scientifique sur le séchage des agromatériaux est unanime sur l’effet positif de la température de l'air, l’effet négatif de l'humidité relative de l'air et de l'épaisseur vis-à-vis du temps de séchage. Cependant, malgré un nombre important d’études, des conclusions contradictoires sont notées en termes de corrélations entre la cinétique de séchage et la vitesse de l'air qui, selon certains auteurs, n’entraîne aucune modification du séchage; alors que certains travaux ont tenté d'établir des modèles empiriques entre la diffusivité effective et la vitesse de l'air ; ce qui est fondamentalement erroné. L’objectif de cette thèse est d’analyser les phénomènes de transfert pendant le processus du séchage et d'identifier le phénomène limitant entre les transferts internes et externes. Ce travail aboutir à l’identification de la vitesse critique de l'air CAV capable de rendre la diffusion interne de l’eau comme phénomène limitant. La CAV doit donc dépendre de la diffusivité effective et de la taille du produit. À partir de résultats expérimentaux qui couvrent de larges plages de température d’air, de teneur en eau, et de taux d'expansion absolu, un modèle empirique a été établi
Great research works support the sector of drying of fruits and vegetables in a number of ways. Each year, experimental results and mathematical modelling try through conventional and innovative technological processes to protect agricultural products from seasonality and variability in the market prices. Nonetheless, there still exist considerable issues to improve and control this strategic agricultural sector. Swell-drying is very relevant drying process coupling hot air dehydration with Instant Controlled Pressure Drop (DIC). In the present work, carrot and apple were used as a fruit and vegetable model. Scientific literature on drying is unanimous that the drying time decreases with increasing air temperature, decreasing air relative humidity, and reducing thickness. However, the effect of airflow velocity leads to contradictory conclusions. Some authors have claimed that it does not trigger any modification of drying; while some articles tried to establish empirical models of the effective diffusivity versus airflow velocity; what is fundamentally erroneous. This thesis aims at analyzing external and internal transfer phenomena during drying. So, it was possible to recognize the Critical Airflow Velocity CAV depending on the effective diffusivity and the product size, to have the internal water transfer as the limiting phenomenon. From experimental results, an empirical model was established between the effective moisture diffusivity and airflow temperature, water content, and absolute expansion ratio

La problématique de cette thèse repose sur la caractérisation de l'aptitude variétale des pommes à la transformation industrielle. Trois objectifs principaux ont guidé cette étude. Le premier objectif était d'identifier parmi dix variétés de pommes, celles étant les plus aptes à deux types de transformation industrielle : la 5ème gamme et la spécialité fruitière. Cette sélection a été effectuée par une analyse des propriétés mécaniques des fruits avant et après transformation. Au final, cinq variétés différentes ont été choisies pour chaque type de procédé. Le deuxième objectif était d'évaluer l'incidence de la maturité des fruits en post-récolte ainsi que la durée des traitements thermiques appliqués, sur les propriétés mécaniques, sensorielles et les marqueurs biochimiques en lien avec l'évolution de la texture des produits transformés. La caractérisation physique et sensorielle a permis de confirmer le fort impact du génotype des pommes sur la qualité des produits finis. L'analyse des polysaccharides pariétaux a mis à jour une solubilisation des composés pectiques liée au stockage et à la cuisson des fruits. Le troisième objectif a été de réaliser un suivi du devenir de certains polyphénols ainsi que leur activité, en fonction de la variété, et au cours de la transformation industrielle. Le procédé 5ème gamme préserve globalement ces composés. En revanche pour le procédé « spécialité fruitière », une dégradation est observée sur certaines variétés.

Penicillium includes some of the most concerning postharvest pathogens of pome and citrus fruit. The pathogenicity and aggressiveness of selected Penicillium spp. previously isolated from South African and European Union fruit export chains were investigated on pome and citrus fruit. New insight and findings were documented in this study. Penicillium digitatum, the most aggressive pathogen on citrus, was also identified the most aggressive on „Beurre Bosc‟, „Beurre Hardy‟ and „Sempre Rosemarie‟ pears. It was also the third most aggressive species on „Granny Smith‟ and „Cripps Pink‟ apples. To our knowledge this is the first report where P. digitatum has been described as an aggressive pathogen on certain pome fruit cultivars. The most concerning species in terms of decay on the evaluated apple cultivars („Royal Gala‟, „Granny Smith‟, „Golden Delicious‟, „Topred‟ and „Cripps Pink‟) and two pear cultivars („Packham‟s Triumph‟ and „Forelle‟) were P. expansum and P. crustosum respectively. New reports concerning spoilage caused by these species were noted on citrus. Penicillium expansum decay and tissue-response lesions were noted on „Nules Clementine‟, „Owari Satsuma‟, „Delta Valencia‟, „Midknight Valencia‟ and „Eureka‟ seeded. Penicillium crustosum caused decay and tissue-response lesions on „Nules Clementine‟, „Nova‟, „Owari Satsuma‟, „Delta Valencia‟, „Cambria Navel‟, „Eureka‟ seeded and „Star Ruby‟. In contrast to more aggressive infections and large surface lesions, some tissue-response lesions sporulated despite their small size, thus allowing the species to complete their life cycle. The second most aggressive species affecting citrus was P. italicum. Pathogenicity of P. solitum was also confirmed on some apple and pear cultivars, although a broader cultivar range and higher level of aggression was observed on pears. Penicillium brevicompactum was only found to be pathogenic on pears. New information regarding host-Penicillium interactions, the potential of cross-infection and the impact each species may have on fruit moving through the market chain was added. Future studies should examine the link between host susceptibility as influenced by maturity and the pathogenic potential of non-host pathogens. Further research is needed to elaborate on the pathogenicity of P. digitatum on pome fruit. Information on market-end losses, the causal agents involved, and inoculum levels and sources may prove beneficial in solving industry problems at the retail-end.
Dissertation (MScAgric)--University of Pretoria, 2014.
lk2014
Microbiology and Plant Pathology
MScAgric
Unrestricted

The public concern over synthetic pesticides in foods and the environment has created an interest to find effective and safe non-fungicide means of controlling postharvest pathogens. The overall objective of this thesis was to evaluate the effect of potassium silicate, yeast antagonists and hot water dip treatment to control postharvest grey mould and blue mould of pome fruits, caused by Botrytis cinerea and Penicillium expansum, respectively. Botrytis cinerea and Penicillium expansum were isolated from infected strawberry and pear fruits, respectively. These isolates were found to be non-resistant to YieldPlus® (Anchor yeast, Cape Town, South Africa), a biofungicide containing a yeast Cryptococcus albidus. A total of 100 epiphytic yeast isolates were obtained from the fruit surface of “Golden Delicious” apples and “Packham’s Triumph” pears, and screened against B. cinerea and P. expansum. Fifteen yeast isolates reduced grey mould incidence by > 50%, when applied four hours before inoculation with B. cinerea. Similarly, seven yeast isolates reduced blue mould incidence by > 50%, when applied four hours before inoculation with P. expansum. YieldPlus® and yeast Isolate YP25 provided the best control of B. cinerea, while Isolate YP60 and YieldPlus® provided the best control of P. expansum on “Golden Delicious” apples. A mixture of YP25 and YP60 provided complete control of both B. cinerea and P. expansum, when applied to “Golden Delicious” apples before inoculation with either B. cinerea or P. expansum. Electron microscopy studies showed that yeast Isolates YP25 and YP60 inhibited the mycelial growth of B. cinerea and P. expansum, respectively. Preventative and curative application of potassium silicate resulted in reduced incidence of B. cinerea or P. expansum of “Golden Delicious” apples. Electron microscopy studies indicated that potassium silicate inhibited the growth of B. cinerea and P. expansum. Furthermore, treatment of “Golden Delicious” apples with either potassium chloride or potassium hydroxide resulted in reduced incidence of both B. cinerea and P. expansum. In vivo tests showed that the disease incidence of P. expansum and B. cinerea on “Golden Delicious” apples was reduced by hot water dip treatments at 58-60°C for 60 to 120 seconds, compared with the control fruit treated with sterile distilled water, without causing skin damage. The use of potassium silicate, yeasts (Isolates YP25 and YP60), YieldPlus® and the antagonists mixture (YP25+YP60) in combination, resulted in the control of B. cinerea and P. expansum of “Golden Delicious” apples compared with Imazalil® treated fruit.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

碩士
朝陽科技大學
應用化學系生化科技碩博士班
103
In this article, we investigate the learning outcomes, including the science misconception and its correction, for preschool children on a science curriculum with the topic of “browning effect of the cut-section of vegetable and fruits” through prediction-observation-explanation （POE）teaching strategy. The subject includes 28 pre-school children in level 1 and level 2 of the kindergarten the author taught. The teaching program, composed of six activities integrating four major concepts, was carried out in 16 successive curriculums over a period of two months. The teaching effects were quantitatively analyzed by descriptive statistics, independent-samples and paired-samples T tests and analysis of covariance （ANCOVA）together with qualitative observation. The results showed that: 1.In the prediction stage, the misconception of pre-school children toward the browning effect of vegetable and fruits was restricted by the experience and expression ability 2.In the observation stage, the systemic and multiple observation activities lead to enrich the children’s experience toward the browning effect and shape the relative scientific conceptions. 3.In the explanation stage, utilization of teaching aids could promote the cognition toward natural phenomena. 4.POE teaching strategy is helpful in constructing the scaffold for scientific inquiry for pre-school children. 5.In some of the activities, the learning outcomes for level 1 children is higher than that of level 2 children. This result indicates the earlier the systematic teaching strategy could be involved in the observation of natural phenomena, the more prominent the effect to assist the children to build up their scientific conception. 6.There is no significant difference in learning outcomes between genders.