Dissertations / Theses on the topic 'Fruit quality'

Thesis (MScAgric)--Stellenbosch University, 2013.<br>ENGLISH ABSTRACT: Fruit size and the integrity of the rind are key components that determine the value of a citrus fruit. The application of 2,4-dichlorophenoxy acetic acid (2,4-D) to reduce splitting, a physiological disorder which entails cracking of the rind as well as to increase fruit size was conducted on three different split-susceptible mandarin and two split-susceptible orange cultivars. Treatments were applied directly after the physiological fruit drop period, as well as in January and February at 10 mg·L-1, alone or in combination with calcium (Ca), potassium (K) or gibberellic acid (GA3). Application of 2,4-D directly after physiological fruit drop, either alone or in a tank-mix with K, consistently reduced the number of split mandarin fruit, with later applications in January and February generally being ineffective. Post physiological fruit drop application of 10 mg·L-1 2,4-D significantly increased growth rate (mm.day-1) of all the mandarin cultivars, resulting in increased fruit size. Differences in sensitivity of cultivars to 2,4-D were evident, with the January application reducing the splitting in ‘Midknight’ Valencia. However, all the 2,4-D treatments reduced the fruit growth rate of the orange cultivars. The 2,4-D treatments, in terms of splitting, increased rind thickness, -strength and -coarseness of ‘Marisol’ Clementine, throughout fruit development. In addition fruit diameter and –length increased to such an extent that the fruit shape was altered (reduced d/l-ratio), reducing the potential of the rind to crack and the fruit to split, however rind coarseness of treated fruit was also increased. There were no major negative side effects on internal and external fruit quality, except for a possible reduction in juice content (%). Therefore, 10 mg·L-1 2,4-D can be applied directly after physiological fruit drop on ‘Marisol’ Clementine and ‘Mor’ mandarin to reduce fruit splitting.<br>AFRIKAANSE OPSOMMING: Vruggrootte asook die integriteit van die skil is belangrike aspekte in die bepaling van ʼn sitrusvrug se waarde. Die toediening van 2,4-dichlorofenoksie asynsuur (2,4-D) om vrugsplit, 'n fisiologiese defek wat tot die kraak van die sitrusskil lei, te verminder is getoets op drie mandaryn- en twee lemoenkultivars. Hiermee saam is die potensiaal van 2,4-D om vruggrootte te verbeter ook geëvalueer. Die 2,4-D behandelings is direk na die fisiologiese vrugval periode toegedien, asook in Januarie en Februarie, teen 10 mg·L-1, alleen of in kombinasie met kalsium (Ca), kalium (K) of gibberelliensuur (GS3). Al die mandarynkultivars het ʼn vermindering in die totale aantal gesplete vrugte getoon indien die 2,4-D (enkel of in kombinasie met K) toegedien was direk na fisiologiese vrugval. Suksesvolle behandelings het ook 'n toename in vruggrootte tot gevolg gehad. Toediening van behandelings in Januarie en Februarie was oor die algemeen oneffektief. Verskille in kultivar sensitiwiteit teenoor 2,4-D is gevind, met vrugsplit in ‘Midknight’ Valencia wat verminder was deur die Januarie toediening van 2,4-D. Al die 2,4-D behandelings het vruggrootte van die lemoenkultivars verlaag. Daar is bevind dat die 10 mg.L-1 2,4-D, enkel of in kombinasie met K, ‘n toename in beide skildikte en –sterkte van ‘Marisol’ Clementine teweeg bring asook ʼn growwer skil. Behandelings met 2,4-D het vrugdeursnee en –lengte laat toeneem, wat ʼn verandering in vrugvorm tot gevolg gehad het, tot so ʼn mate dat vrugte minder geneig was om gesplete te wees. Behalwe vir ʼn moontlike verlaging in die sapinhoud (%) van vrugte, was daar geen noemenswaardige negatiewe effekte op interne en eksterne vrugkwaliteit nie. Die toediening van 10 mg.L-1 2,4-D direk na fisiologiese vrugval kan dus aanbeveel word op mandaryn kultivars wat geneig is tot vrugsplit.<br>The Citrus Academy

Quality and traceability are the winning combination for the development of a modern agriculture, where other functions, related to territorial, environmental and social skills, are gradually taking place aside from the traditional economic task. In the last decade quality has become an essential feature to ensure the access into the market and an effective competition to many ever-growing exporting countries. Quality is defined as the set of features of a food that leads to consumer satisfaction and includes sensory properties, shelf-life, product safety and functional properties. The systems for the traceability of food products along specified stages of production, processing and distribution play a key role in assuring safety, quality and origin of food and are typically based on a continuous paper-trail and effective labelling. However, analytical techniques that enable the determination of the provenance of a food product provide an independent mean of control and also help to prove product authenticity, to combat fraudulent practices and to control any adulterations. The capability to certify food origin or authenticity of a product is of significant economic importance for the agri-food stakeholders in different countries. For example, some food products (organic and/or with certifications of origin) can boast EC recognition on their label. This adds value to such products in terms of marketability and increased export value. The present work has been developed starting from this perspective, focusing on the quality and traceability of Mediterranean fruits and their derivatives grown in Sicily.

Plants synthesize a diverse array of phytochemicals in response to interactions with herbivores, pathogens, and commensal microbes. These phytochemicals may simultaneously enhance crop defense and quality, representing a potential pest management strategy. However, plant chemical responses to different types and levels of biotic interactions remain unclear, particularly in fruit tissues, and the feasibility of inducing these defenses through elicitor application in field environments also requires further examination. Thus, apples were used to 1) examine the impact of distinct communities of biotic interactions among plants, insects, and microbes on fruit phenolic chemistry, and 2) examine the impact of the phytohormones jasmonic acid (JA), salicylic acid (SA), and melatonin (M) on fruit phenolic chemistry and resistance against pests and pathogens. Ultimately, phenolic defenses were induced by fungal damage primarily in ripe pulp tissues, where there was also a positive relationship between fungal endophyte and phenolic diversity, supporting a broad hypothesis that chemical diversity may increase with biotic diversity. Additionally, two compounds were upregulated in response to fungal damage: chlorogenic acid and an unidentified benzoic acid. Elicitor applications did not affect phenolic chemistry, but the combined application of JA-SA analogues had some chemical or physical effect, as this treatment reduced emergence of the insect Rhagoletis pomonella. Thus, fruit induced defenses may be tissue-specific and subject to temporal, environmental, or genotypic variation. Overall, these chapters examined the relationship between biotic interactions and induced fruit chemistry, with the goal of improving understanding of plant-microbe-insect interactions and incorporating these interactions into more sustainable agricultural practices.<br>Master of Science<br>Plants may produce a diverse array of defensive phytochemical compounds in response to interactions with herbivores, pathogens, and the microorganisms that reside within plant tissues. These phytochemicals may simultaneously improve crop defenses and quality, representing a potential agricultural management strategy. However, plant chemical responses to different types and levels of biotic interactions are not well-understood, particularly in fruit tissues, and the feasibility of activating these defenses in fruits through the application of phytohormones that regulate defense pathways as a potential management strategy also requires further examination. Thus, apples were used to 1) examine the impact of distinct communities of biotic interactions among plants, insects, and microbes on fruit chemistry, focusing on phenolics, an important class of phytochemical compounds, and 2) examine the impact of the defense-activating phytohormones jasmonic acid (JA), salicylic acid (SA), and melatonin (M) on fruit phenolic chemistry and resistance against pests and pathogens. Ultimately, phenolic defenses were activated by fungal damage primarily in ripe pulp tissues, where there was also a positive relationship between fungal endophyte and phenolic diversity, supporting a broad hypothesis that chemical diversity may increase with biotic diversity. Additionally, two compounds were produced in response to fungal damage: chlorogenic acid and an unidentified benzoic acid. Phytohormone applications did not affect phenolic chemistry, but the application of the combined JA-SA analogues had some chemical or physical effect, as this treatment reduced emergence of the insect Rhagoletis pomonella. Overall, the phytochemical defenses activated by biotic interactions in fruits may occur primarily in certain tissue types, and may also vary due to environmental conditions, time of year, or plant species. These chapters examined the relationship between fruit chemistry and biotic interactions with the goal of improving understanding of plant-microbe-insect interactions and incorporating these interactions into more sustainable agricultural practices.

Thesis (MScAgric)--Stellenbosch University, 2002.<br>ENGLISH ABSTRACT: Fruit size can be a problem in 'Clementine' mandarin and 'Valencia' orange in the Western Cape region of South Africa. Small fruit is not only unacceptable to the consumer but is also more difficult and expensive to harvest. Means of alleviating this problem is to manage the crop load. Hand thinning trials were conducted to evaluate the effect of timing and severity thereof in enhancing fruit size. The benefits of enhancing large fruit size was obtained by a heavy-thinning (60% fruitlet removed) treatment, but the actual benefits were offset by a reduction of total yield. Yield was reduced up to 30% when heavy thinning treatments were applied. No effect on early or late treatments were obtained since the trial was conducted rather late (4 to 6 weeks after the physiological fruit drop period) to obtain the desirable results. However, better packouts are expected with thinning treatments since blemished fruit are also removed. The effect of multiple 2,4-dichlorophenoxy propionic acid (dichlorprop) sprays were also evaluated on 'Nules Clemetine' mandarin. Comparing multiple sprays with a single spray, it was observed that more than one spray was no better in improving fruit size. The use of multiple dichlorprop sprays resulted in no additional yield reduction, while internal fruit quality was also not affected. The best results were obtained with dichlorprop at 50 mg. L-1 • The use of dichlorprop with different surfactants was evaluated in both 'Clementine' mandarin and 'Valencia' orange. The fruit size was increased from 50 mg. L-1 up to 100 mg. L-1 • Yield was usually not affected but, where reductions were experienced, yield of large fruit (>55 mm) was not significantly affected. In the 'Valencia' orange trials, during the first year, dichlorprop was sprayed relatively late (fruit diameter: 19 mm). No fruit size, yield and internal fruit quality effects were observed. The following year, when early and late sprays (fruit diameter at spray time = 8 and 12 mm, respectively) were evaluated, it was observed that late sprays had no effect on fruit size, whereas fruit size (48 fruit per carton) was significantly increased by early sprays. This implies that the dichlorprop effect on fruit size is during the early stages of fruit development, just after or during the late stage of the physiological fruit drop period. Yield was drastically reduced by up to 35%, which affected the actual kilograms of large fruit adversely in some treatments. Juice percentage was inconsistent and tended to be reduced by dichlorprop application. Dichlorprop tended to increase TSS slightly in year one and significantly so in year two, but did not affect the TSS:TA ratio. The use of Orchex mineral oils as surfactant at 150 mL. 100 L-1 was effective and seemingly allowed lower rates of dichlorprop to be used. Therefore, surfactants seemed to show potential in enhancing dichlorprop efficiency to reduce the application cost. The dichlorprop-sprayed fruit was used to measure carotenoid content of the rind during the later stage of fruit development. Observations indicate that dichlorprop-sprayed fruit at 50 mg. L-1 obtained better carotenoid content in both 'Clementines' mandarin and 'Valencia' orange. Also, fruit exposed to light had higher carotenoid levels as compared to fruit shaded with brown paper bags. However, dichlorprop-sprayed fruit at 100 mg. L-1 , even though exposed to light did not show significant differences with unsprayed in both shaded and exposed conditions. Therefore, no consistent effect of dichlorprop was established on total carotenoid content of the rind.<br>AFRIKAANSE OPSOMMING: Vruggrootte van 'Clementine' mandaryn en 'Valencia' lemoene kan 'n probleem wees in die Wes Kaap area van Suid Afrika. Klein vrugte is nie net onaanvaarbaar vir die verbruiker nie, maar is ook moeilik om te oes. Vrugdrag manipulasie is een manier om hierdie probleem te beheer. Hand uitdunningsproewe is uitgevoer om die effek van tyd en graad van uitdunning op vruggrootte te bepaal. Strawwe vruguitdunning (60% van vruggies verwyder) het groter vrugte tot gevolg gehad maar het gelei tot 'n verlaagde opbrengs. Opbrengs is tot soveel as 30% verlaag met die strawwe vruguitdunning. Vroeë en laat behandelings het egter geen effek gehad nie, aangesien die proewe te laat uitgevoer is (4 tot 6 weke na die fisiologiese vrugvalperiode) om die gewenste effek te verkry. Beter uitpak word verwag na uitdunning, aangesien vrugte met letsels ook verwyder word. Die effek van veelvuldige 2,4-dichlorofenoksie-propioonsuur (dichlorprop) spuite IS ook geëvalueer op 'Nules Clementine' mandaryn. Daar is geen verskil gevind tussen enkel en veelvuldige spuite in terme van vruggrootteverbetering nie. Die gebruik van veelvuldige dichlorprop spuite het nie tot 'n verlaging in opbrengs gelei nie, en interne vrugkwaliteit is ook nie beïnvloed me. Die beste resultate is verkry met die 50 mg. L-1 dichlorprop behandeling. Die gebruik van dichlorprop saam met verskillende benatters is op beide 'Clementine' mandaryn en 'Valencia' lemoene geëvalueer. Vruggrootte het toegeneem vanaf 50 mg. L-1 tot 100 mg. L-1 • Opbrengs was net in sekere gevalle verlaag en dan sonder 'n betekenisvolle verskil in groot-vrug produksie (>55 mm: Clementines). Tydens die eerste jaar van die 'Valencia' lemoen proef is die dichlorprop relatief laat gespuit (vrug deursneë: 19 mm). Daar was geen effek op vruggrootte, opbrengs en interne vrugkwaliteit nie. Tydens evaluasie van vroeë en laat bespuitings die volgende jaar is waargeneem dat laat bespuitings geen effek op vruggrootte gehad het nie, terwyl vruggrootte (48 vrugte per karton) betekenisvol verhoog is deur die vroeë bespuitings (Vruggrootte voor bespuiting = 8 en 12 mm, onderskeidelik). Dit impliseer dat dichlorprop se effek op vruggrootte gedurende die vroeë stadiums van vrugontwikkeling is, net na of gedurende die laat stadiums van die fisiologiese vrugvalperiode. Opbrengs is drasties verlaag deur dichlorprop, tot soveel as 35% wat die kilogram groot vrugte negatief beïnvloed het in sommige behandelings. Sappersentasie was nie konsekwent affekteer nie, maar is verlaag deur die dichlorprop bespuitings. Dichlorprop het die TSS effens verhoog in beide jare, maar het geen effek gehad op die TSS:TA verhouding nie. Die gebruik van Orchex minerale olie as benatter was effektief by 150 mL. 100 L-1 , en laat klaarblyklik die gebruik van dichlorprop by laer konsentrasies toe. Dus, kom dit voor dat benatters die potensiaal het om die effektiwiteit van dichlorprop te verbeter wat lei tot 'n verlaging in toedieningskoste. Die dichlorprop gespuite vrugte is gebruik om karotenoïed-inhoud van die skil te meet tydens die laat stadiums van vrugontwikkeling. Vrugte gespuit met dichlorprop teen 'n konsentrasie van 50 mg. L-1 het 'n beter karotenoïed-inhoud in beide 'Clementine' mandaryn en 'Valencia' lemoene tot gevolg gehad. Vrugte blootgestel aan lig het ook 'n hoër karatenoïedkonsentrasie gehad as vrugte wat met bruin papiersakke bedek was. Dichlorprop bespuite vrugte teen 100 mg. L-I, alhoewel blootgestel aan lig, het geen betekenisvolle verskil gehad in vergelyking met onbespuite vrugte nie. Dus is daar geen konsekwente effek van dichlorprop op karotenoïde inhoud van die skiI waargeneem nie.

Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(農学)<br>甲第17616号<br>農博第1978号<br>新制||農||1009(附属図書館)<br>学位論文||H25||N4737(農学部図書室)<br>30382<br>京都大学大学院農学研究科地域環境科学専攻<br>(主査)教授 縄田 栄治, 教授 米森 敬三, 教授 間藤 徹<br>学位規則第4条第1項該当

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 (MSc)--Stellenbosch University, 2002.<br>ENGLISH ABSTRACT: Successful export of South African fresh fruit requires fruit of a high quality. Variable fruit quality within a consignment is detrimental to effective marketing of the product. The light microclimate under which the fruit develops is one of the factors that affect within-tree and between-tree variation in quality, maturity and yield. Light exposure effects on fruit quality at harvest and after commercial storage and ripening periods, as well as the physiological mechanisms of these responses to light exposure were studied. Increased exposure to light resulted in the development of typical sun leaf characteristics, with the associated increase in leaf nitrogen concentration and photosynthetic rates. Size and mass of 'Laetitia' plums and 'Cripps' Pink' apples increased with increasing exposure to light. Shade treatments were only started after the initial phase of cell / division was complete. Increased size of the fruit was likely due to the improved carbon balance of the exposed foliage and fruit from the end of cell division until harvest. The transpiration stream was higher in the more exposed foliage compared to the shaded parts of the canopy. This was supported by increased transpiration rates and decreased midday water potentials of exposed leaves. 'Songold' plums and 'Rosemarie' pears were also investigated in the first season, but results were not conclusive. Increased exposure to light was associated with advanced maturity of 'Laetitia' plums at harvest. Shaded fruit were able to attain a similar level of maturity as exposed fruit during storage and ripening periods. At harvest and after the storage and ripening periods, exposed fruit had a higher total soluble solid (TSS) content and therefore an improved eating quality. At harvest, blush colour of 'Laetitia' plums increased with increased exposure to irradiance. Blush colour continued to develop during storage and ripening, and after the ripening period it was evident that blush colour development was associated with a dosage effect i.e. exposure to a cumulative level of irradiance gives the fruit the potential to develop a certain amount of blush colour. Fruit exposed to more than 70% photosynthetic photon flux density (PPFD) were .able to develop to a similar level of blush colour, whereas, fruit exposed to less than 50% PPFD were not able to attain the same level of blush colour. Increased exposure to light did not result in advanced maturity of 'Cripps' Pink' apples at harvest, but it did lead to improved blush colour and increased TSS levels. Blush colour of 'Rosemarie' pears was also dependent on exposure to light from four weeks before harvest. Exposed 'Laetitia' plums had a greater whole fruit content of Mn and B, but concentration on a dry mass basis of P, K, and B decreased with increasing light. Exposed 'Cripps' Pink' apples had increased whole fruit content of P, K, Ca, Mg, Mn, Fe, Cu and B, but concentration on a dry mass basis of K and Na decreased with increasing light. Nutrient content is often associated with the incidence of internal disorders of fruit after storage and further investigation of this effect is necessary as internal disorders were virtually absent in this study. The termination of irrigation shortly before harvest in order to advance the maturity of all the fruit to a similar level, and the subsequent strip harvest of the fruit on a single harvest date, is a practice commonly used by South African plum producers to reduce cost and ostensibly to improve fruit quality. The effect of this practice on 'Songold' plum quality at harvest, after storage and after ripening was also studied. Drip-irrigated plums and plums subjected to soil drying had a better eating quality and were more marketable than micro-irrigated and non-droughted fruit. Following commercial storage and ripening periods these fruit were firmer, had a higher TSS content and were of a similar size and mass to micro-irrigated and non-droughted fruit. The extended harvesting period, in contrast to a strip harvest, allowed the fruit that were smaller and less mature at the beginning of the period to attain a greater size and advanced maturity toward the end of the harvesting period.<br>AFRIKAANSE OPSOMMING: Suksesvolle uitvoer van Suid-Afrikaanse vars vrugte vereis volgehoue hoë gehalte. Wisselvallige vruggehalte binne 'n besending is nadelig vir die effektiewe bemarking van die produk. Die lig mikroklimaat waaronder die vrug ontwikkel is een van die faktore wat variasie in gehalte, rypheidsstadium en opbrengs binne die boom en tussen bome beïnvloed. Die effek van verhoogde ligblootstelling op vruggehalte by oes, na kommersiële opberging en na die rypwordingsperiode, sowel as die fisiologiese meganismes van die reaksie van verhoogde ligblootstelling is bestudeer. Verhoogde blootstelling aan lig lei tot die ontwikkeling van tipiese son-blaar karaktertrekke, met die gepaardgaande verhoging in blaar stikstof konsentrasie en fotosintetiese tempo. Grote en massa van 'Laetitia' pruime en 'Cripps' Pink' appels het toegeneem met verhoogde blootstelling aan lig. Skadu behandelings is eers begin na die einde van die periode van selverdeling. Toenemende grootte van die vrugte is as gevolg van die verbeterde koolstofbalans van die blootgestelde blare en vrugte vanaffase II van vruggroei tot oestyd. Die transpirasie stroom is geallokeer na die blootgestelde blare. Dit word ondersteun deur die verhoogde transpirasie tempo en verminderde middag waterpotensiaal van die blootgestelde blare. 'Songold' pruime en 'Rosemarie' pere is ook bestudeer, maar die uitslae is nie so oortuigend nie. Toenemende blootstelling aan lig is geassosieer met gevorderde rypheid van 'Laetitia' by oes. Dit was moontlik vir skadu vrugte om dieselfde rypheidsvlak as blootgestelde vrugte te bereik, tydens die opberging en rypwording periodes. Teen oestyd en na opberging en rypwording, het blootgestelde vrugte 'n hoër suiker inhoud gehad en dus 'n hoër eetgehalte. Teen oestyd, het die bioskleur van die pruime toegeneem met toenemende blootstelling aan lig. Ontwikkeling van bloskleur het aangehou gedurende opberging en rypwording, en na die die rypwordings periode was dit duidelik dat bioskleur ontwikkeling met 'n dosis-effek geassosieer word, m.a.w. blootstelling aan 'n sekere opgestapelde vlak van lig gee die vrug die potensiaal om 'n sekere hoeveelheid bioskleur te ontwikkel. Vrugte wat meer as 70% ligblootstelling gekry het, het dieselfde bioskleur ontwikkel, maar vrugte wat minder as 50% ligblootstelling gekry het, het minder bloskleur ontwikkel. Toenemende blootstelling aan lig het nie gelei tot gevorderde rypheid van 'Cripps' Pink' appels teen oestyd nie, maar dit het wel gelei tot verbeterde bioskleur en verhoogde suiker inhoud. Bloskleur van 'Rosemarie' pere is afhanklik van blootstelling aan lig kort voor oestyd. Blootgestelde 'Laetitia' pruime het 'n verhoogde vrug inhoud van Mn en B met verhoogde ligblootstelling gehad, maar die konsentrasie van P, K en B op 'n droë massa basis het afgeneem met verhoogde ligblootstelling. Blootgestelde 'Cripps' Pink' appels het 'n verhoogde vrug inhoud van P, K, Ca, Mg, Mn, Fe, Cu en B met verhoogde ligblootstelling gehad, maar die konsentrasie van K en Na op 'n droë massa basis het afgeneem met verhoogde ligblootstelling. Voedingstof inhoud is geassosieer met die voorkoms van interne probleme in vrugte na opberging en verdere navorsing oor hierdie effek is nodig. Die terminering van besproeiing kort voor oestyd met die doelom die rypheid van al die vrugte op dieselfde vlak te kry sowel as die gepaardgaande oes van al die vrugte op een dag, is 'n algemene praktyke wat gebruik word deur Suid-Afrikaanse pruim produsente om kostes te beperk en oënskynlik, om vruggehalte te verbeter. Die effek van hierdie praktyke op 'Songold' pruim gehalte teen oestyd, na opberging en na rypwording is ook bestudeer. Drup-besproeide pruime en pruime wat blootgestel is aan grond uitdroging het 'n beter eetgehalte en is meer bemarkbaar as mikro-besproeide en nie-droogte geïnduseerde vrugte. Na kommersiële opberging en rypwording periodes het hierdie vrugte 'n hoër fermheid en suiker inhoud gehad, en 'n gelyksoortige grootte en massa as mikrobesproeide en nie-droogte geïnduseerde vrugte. Die verlengde oesperiode het die kleiner en minder ryp vrugte aan die begin van die periode 'n kans gegee om toe te neem in grootte en 'n gevorderde vlak van rypheid te bereik aan die einde van die oesperiode.

Quality is increasingly important for retailers, who tend to look for more definitive assessment criteria. Taste has become a major issue over past years for consumers, who are seeking higher quality produce. For banana fruit, at least one major retailer is asking TSS measurement in addition to the usual assessment based on skin colour. At the same time organic produce sales are increasingly important for ripeners and retailers to consumers. This study investigated variability in banana pulp with regard to sampling position from proximal, middle and distal portions. Also two different devices, the traditional pocket refractometer and the digital refractometer were evaluated. TSS was measured on juice obtained directly from the pulp, as practised by one supermarket representative, versus the more conventional method of homogenizing pulp samples in distilled water. Finally, a comparison of postharvest qualities of conventionally and organically grown banana fruit from nearby plantations in the Dominican Republic was made. This comparison involved several harvest times over the seasonal period from February to June 2001. Green mature Cavendish bananas var. Grand Nain were imported from the Dominican Republic by SH Pratt’s & Co. (Luton, UK). Both the conventionally and the organically grown bananas from the same area were held at about 15 degrees C during shipping and handling. The fruit were then ripened in a postharvest laboratory in the UK with a shot of 100 muL/L ethylene applied for 48 hours at 20 ±1 degree C. They were then assessed over 12 days of shelf life at this same temperature and at 60 ±10 % relative humidity. Fruit weight (g), colour (L* and H degrees), acidity (ml of 0.1 N NaOH), firmness (N) and TSS (%Brix) were assessed every second day during shelf life. In addition, starch breakdown was visualised by dipping slices of banana in iodine solution. Sensory analysis on the ripened fruit was also made with 30 panellists for four out of six of the harvest times.

The purpose of this project was to test and implement recent research of polarization and scatter properties that suggest using a cross polarization imaging system to reduce glare artifacts. In particular, the use of this research is to improve the machine vision of apple quality detection in the food industry. The automated measurement system was implemented by acquiring pictures at different angles and different polarization states of apples. The opto-mechanics, system integration, synchronization and data collection are controlled with LabVIEW.

Thesis (MScAgric)--Stellenbosch University, 2000.<br>ENGLISH ABSTRACT: The effect of foliar application oftriadimenol (a triazole), Promalin'", or scoring branches on fruit set, fruit size and fruit quality of 'Royal Gala' apples were evaluated. Four treatments were tested, viz., (a) an unsprayed control, (b) triadimenol sprayed on 6 March 1997 (one month after harvest) and then every two weeks for 8 weeks until leaf drop, as well as at mouse ear and full bloom, (c) as treatment b, plus Promalin® two weeks after full bloom, and (d) Promalin® two weeks after full bloom. Four scoring treatments were tested, viz., (a) a control, (b) scoring at full bloom, (c) scoring two weeks after full bloom, and (d) scoring four weeks after full bloom. Promalin® application two weeks after full bloom improved fruit size without any detrimental effects on fruit quality. This application was in addition to the standard commercial applications of Promalin'" as part of the chemical thinning program. The possible negative effect of the G~+7 on return bloom was however not determined. The scoring treatments were not severe enough to influence growth and development significantly and should be investigated again in the future. The influence of bearing position on apple flower and subsequent fruit quality was evaluated. At full bloom in the 1997/98 season, ten flower clusters from the following bearing positions were collected and evaluated: (a) dorsal spurs, (b) ventral spurs, (c) terminal on bourse shoot, (d) terminal on long shoot, and (e) lateral on long shoots. The same bearing positions were used, one week after full bloom, for the 1998/99 season. The flowering pattern was monitored for both seasons and just prior to harvest in both seasons the length and diameter of the fruit were measured as well as the length of the bourse shoot that had developed from the same bud. Fruit thinning by hand was done in 1997 by thinning to the largest fruit per cluster, but no thinning was done in the 1998 season. The results obtained in the morphological analysis of the flower cluster of 'Royal Gala' were not very consistent. In general, the dorsal spurs appeared to be the better quality flowers and the "king" flower is believed to be the best quality flower in the cluster as far as the receptacle dimensions are concerned. When fruit were harvested, no fruit on long shoots, either in the terminal or lateral positions, were found. Even though the percentage of these positions were low at bloom, this indicates a low set potential and possibly poor flower quality of these bearing positions in 'Royal Gala'. The size of the fruit at harvest in 1998/99, did not correlate well with the parameters measured at bloom. The correlation coefficients between bourse shoot length and fruit size were significant, but relatively small. We found a positive correlation between developed seed number and fruit dimensions. Thinning and heading pruning cuts affect fruit size and yield of 'Royal Gala' apple trees. During the 1997 winter trees were pruned as follows: (a) control with no further pruning, (b) thinning cuts of only entire secondary branches (branches that were thicker than half of the trunk diameter were removed at the point of attachment to the trunk), (c) thinning cuts of secondary branches and tertiary fruiting units (positioned on branches), (d) thinning of spurs only, without removal of branches or fruiting units, and (e) thinning cuts of branches and tertiary fruiting units combined with heading back of fruiting units into the spurs leaving four bud on the fruiting units. Treatments (b) through (e), were conducted at light or heavy pruning intensities, i.e., by leaving 300 or 150 reproductive buds/tree, respectively. Pruning was followed up by hand thinning of fruitlets to one fruit per cluster. All pruning treatments increased fruit size, primarily because of a indirect fruit thinning effect except the combined thinning and heading treatments where a direct effect resulted in the largest apples without having a negative effect on yield. In winter 1998 trees were pruned as follows: (a) control with no further pruning, (b) heavy thinning of secondary branches and fruiting units leaving 250 reproductive buds/tree, (c) light thinning of secondary branches and fruiting units leaving 400 reproductive buds/tree, (d) heavy thinning of secondary branches and fruiting units combined with heading back into the spurs of the remaining fruiting units leaving 250 reproductive buds/tree, and (e) light thinning of secondary branches and fruiting units combined with heading back into the spurs of the remaining fruiting units leaving 400 reproductive buds/tree. In 1998/99 season the advantage of pruning on fruit size were not observed. Lastly, the effect of artificial extinction (removal) of flower clusters on fruit size and quality of 'Royal Gala' apples were evaluated. Individual branches were pruned as follows: (a) control, (b) 25 % removal of fruiting spurs, (c) 50 % removal of fruiting spurs, (d) 75 % removal of fruiting spurs to test for any possible enhancements of fruit size. No subsequent hand thinning of fruitlets was done. Thinning by artificial extinction methods of the fruit buds did not influence fruit size, colour, seed set or seed development. No significant differences were found between fruit number, but with 50% and 75% bud removal fewer fruit were counted. In these data the absence of any significant fruit size improvement may be due to the lack of subsequent hand thinning of fruitlets.<br>AFRIKAANSE OPSOMMING: Die effek van blaarbespuiting van triadimenol en Promalin® asook ringelering op vrugset, vruggrootte en vrugkwaliteit is geëvalueer. Vier behandelings is toegepas nl: (a) onbehandelde kontrole, (b) triadimenol op 6 Maart 1997 en dan elke twee weke tot en met blaarval asook met "muis oor" en volblom, (c) soos behandeling b, plus Promalin® twee weke na volblom, en (d) Promalin® twee weke na volblom. Vier ringelering behandelings is ook toegepas nl: (a) geen ringelering (kontrole), (b) tydens volblom, (c) twee weke na volblom, en (d) vier weke na volblom. Promalin® bespuiting twee weke na volblom verbeter vruggrootte sonder enige nadelige effekte op vrugkwaliteit. Dit moet ingedagte gehou word dat hierdie behandeling van Promalin® was addisioneel toegevoeg tot die standard kommersiele gebruik van Promalin® wat deel vorm van die chemiese uitdun program. Die moontlike negatiewe effek van GA4+7 op blominisiasie is nie bepaal nie. Die ringelering behandelings was nie straf genoeg nie en dit het nie die groei en ontwikkeling betekenisvol beïnvloed nie en sal in die toekoms weer geëvalueer moet word. Verder is die invloed van draposisies op die appel blomkwaliteit en die daaropvolgende vrugkwaliteit geëvalueer. Met vol blom in die 1997/98 seisoen is tien blom trosse van die volgende draposisies versamel en geëvalueer: (a) dorsale spore, (b) ventrale spore, (c) terminaal op beurslote, (d) terminaal op langlote, en (e) lateraalop langlote. Dieselfde draposisies is versamel, een week na volblom, vir die 1998/99 seisoen. Die blompatroon is gemonitor gedurende beide seisoene. Net voor oes is die vruglengte en - deursnee gemeet as ook die lengte van die beurslote wat van dieselfde knop ontwikkel het as die vrugte. Vruguitdinning met die hand tot die grootste vrug per tros was gedoen in die 1997/98 seisoen, maar nie in die 1998/99 seisoen nie. Die resultate wat gekry is met die morfologiese analise van die blom trosse was nie baie konsekwent nie. In die algemeen vertoon die dorsale spore die beste kwaliteit blomme en die "koning" blomme het die grootste blombodems. Met die oes van die vrugte is geen vrugte op lang lote, hetsy in die terminale of laterale posisies gevind nie. Al was die persentasie van die posisies laag met volblom dui dit op lae setpotensiaal en moontlik ook op 'n lae blom kwaliteit van hierdie draposisies vir 'Royal Gala" appels. Die grootte van die vrugte van die 1998/99 oes korreleer nie goed met die parameters wat tydens blom gemeet is nie. Ongelukkig is die vrugte vir die 1998/99 seisoen nie gedurende die na-blom staduim uitgedun nie, wat daartoe bygedra het dat dit moeilik is om afleidings te maak. Die korrelasiekoeffisient tussen die beurslootlengte en vruggrootte was betekenisvol maar redelik klein. 'n Positiewe korrelasie tussen die aantal goed ontwikkelde sade en vrugdimensie is gevind. Die effek van uitdun en terugsnysnitte op vruggrootte eh opbrengs van 'Royal Gala' is ook geëvalueer. Gedurende die 1997 winter is die bome op die volgende manier gesnoei: (a) geen snoei (kontrole), (b) uitdunsnitte van hele sekondêre takke (takke wat dikker was as die helfde van die stam se deursnee by die punt van aanhegting aan die stam), (c) uitdunsnitte van sekondêre takke en tersiêre vrugdraende takke, (d) uitdun van spore alleen sonder om enige takke te verwyder, en (e) uitdunsnitte van sekondêre takke en tersiêre vrugdraende takke gekombineerd met terugsnysnitte van vrugdraende takke in die spoor sisteem in tot net vier spore per tak oorbly. Vir behandelings (b) tot (e) was die behandelings opgedeel in 'n ligte en 'n strawwe uitduning van knoppe deur onderskeidelik uit te dun tot 300 en 150 reproduktiewe knoppelboom. Die snoei was opgevolg deur handuitdunning tot een vrug per tros. Alle snoeibehandelings verbeter vruggrootte, primêr as gevolg van 'n indirekte vruguitdunnings, effek behalwe die behandeling met uitdunsnitte van sekondere takke en tersiêre vrugdraende takke gekombineerd met terugsnysnitte van vrugdraende takke. In hierdie behandeling is daar 'n direkte effek op vruggrootte sonder om 'n negatiewe effek op die oes opbrengs te he. In die winter van 1998 is die bome soos volg gesnoei: (a) geen snoei (kontrole), (b) strawwe uitdun snitte van hele sekondêre takke en vrugdraende takke tot op 250 reproduktiewe knoppe/boom, (c) ligteuitdun snitte van hele sekondêre takke en vrugdraende takke tot op 400 reproduktiewe knoppe/boom, (d) strawwe uitdunsnitte van sekondêre takke en tersiêre vrugdraende takke gekombineerd met terugsnysnitte van vrugdraende takke tot in die spoorsisteem tot op 250 reproduktiewe knoppelboom, en (e) ligte uitdunsnitte van sekondêre takke en tersiêre vrugdraende takke gekombineerd met terugsnysnitte van vrugdraende takke tot in die spoorsisteem tot op 400 reproduktiewe knoppelboom. Geen handuitdunning is gedurende die' seisoen gedoen nie, In die 1998/99 seisoen is geen voordeel van snoei op vruggrootte waargeneem nie. Snoei moet dus opgevolg word deur handuitdunning van vruggies. Laastens is daar na die effek van kunsmatige uitdun van blomtrosse op vruggrootte van 'Royal Gala' appels gekyk. Individuele takke is soos volg gesnoei: (a) kontrole, (b) 25 % verwydering van spore, (c) 50 % verwydering van spore, en (d) 75 % verwydering van spore. Geen opvolg handuitdunning is gedoen nie. Die uitdun tegniek het nie die vruggrootte, - kleur of die hoeveelheid en ontwikkeling van saad beïnvloed nie. Met die 50 % en 75 % verwydering is daar soos verwag minder vrugte geoes. Die rede dat geen vruggrootte verbetering gevind is nie kan moontlik daaraan toegeskryf word dat geen opvolg handuitdunning toegepas is nie.

Mestrado Vinifera EuroMaster - Instituto Superior de Agronomia<br>The objective of this study was to determine the optimal timing of fruit-zone leaf removal for red wine grape cultivars, specifically Vitis vinifera ‘Merlot’, in the Yakima Valley, Washington using four different timings of fruit-zone leaf removal, (i) pre-bloom, (ii) full-bloom, (iii) 3 weeks post-bloom and (iv) no leaf removal (control). Fruit-zone leaf removal is a common canopy management technique, with increasing focus on early (pre-fruit set) timing. Little research exists on the impacts of early fruit-zone leaf removal in semiarid viticultural regions like the inland Pacific Northwest, USA. Shoot growth after leaf removal in the pre-bloom treatment temporarily decreased relative to the no leaf removal treatment (control). The incidence of summer lateral shoot development within the fruit-zone indicates that only pre-bloom fruit-zone leaf removal recovered to control levels by véraison. Percent fruit set was lowest in the pre-bloom treatment. Sunburn, powdery mildew and Botrytis bunch rot did not develop to any significant level in any treatment. Though not statistically significant, fruit-zone leaf removal increased surface temperatures of clusters and compound buds. The scope of this report does not provide adequate data for firm conclusions about the effects of early fruit-zone leaf removal on grapevine development and fruit quality. Outside of the summer lateral shoot data, the fruit-zone leaf removal treatments in this experiment were statistically similar to the no leaf removal treatment. However, trends in the data suggest fruit-zone leaf removal may impact vine vigor, fruit set, and fruit-zone microclimate providing ample cause for further research on this canopy management technique

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

El melón (Cucumis melo L.) es un importante cultivo a nivel mundial, con una producción de 31 millones de toneladas durante el año 2016. Aunque tradicionalmente los programas de mejora genética se han focalizado en el comportamiento agronómico del cultivo, la calidad de fruto se ha convertido recientemente en un objetivo principal. La calidad del fruto es un concepto complejo, que incluye diversos caracteres relacionados con la apariencia visual del fruto y su calidad nutricional y organoléptica. Muchos de estos caracteres están asociados a la maduración de fruto, que es el proceso que sufre el fruto para transformarse en un alimento atractivo para promover la dispersión de la semilla. Los frutos son clasificados, en base a su comportamiento durante la maduración, en climatéricos, cuando la hormona vegetal etileno es sintetizada de manera autocatalítica al comienzo del proceso de maduración, y no climatéricos, para los cuales el etileno no tiene un papel importante. El principal objetivo de este trabajo ha sido estudiar las bases genéticas de la calidad y la maduración del fruto en melón. Hemos desarrollado una población de líneas puras recombinantes (RIL) a partir del cruce entre dos variedades élite, “Védrantais”, altamente climatérica, y “Piel de Sapo” (PS), no climatérica. La diversidad fenotípica en la calidad de fruto y los caracteres asociados a la maduración, incluyendo la producción de etileno, han sido estudiados en profundidad. Un mapa genético de alta densidad ha sido construido usando variantes obtenidas a través de un experimento de genotyping-by-sequencing. Un experimento de mapeo de QTLs reveló cinco genes mayores y 33 QTLs implicados en la apariencia visual del fruto (color, presencia de suturas, moteado), morfología de fruto, contenido en azúcares y peso de semilla. Un segundo experimento de mapeo de QTLs identificó 14 QTLs implicados en la producción de etileno y otros caracteres asociados a la maduración, como degradación de clorofila o formación de una capa de abscisión. Entre ellos, podemos destacar un QTL mayor, ETHQV8.1, implicado en la producción de etileno que afectó a prácticamente todos los caracteres estudiados, localizado en un intervalo de 500 kb del cromosoma VIII. Para diseccionar genéticamente la maduración del fruto, además de la mencionada población de RILs, estudiamos la línea casi isogénica (NIL) climatérica 8M35, con el fondo genético de PS y una introgresión de la accesión exótica PI 161375. 8M35 porta el QTL ETHQB3.5, delimitado en una región de 5Mb del cromosoma III. Se ha seguido una estrategia de clonaje posicional para el mapeo fino de ETHQB3.5, generando un juego diverso de subNILs. Tras múltiples evaluaciones de diferentes subNILs, determinamos que al menos dos factores genéticos diferentes deben estar implicados en el desencadenamiento de la maduración climatérica en la línea 8M35. Uno de ellos, nombrado ETHQB3.5.1, es responsable de la mayor parte del fenotipo y fue delimitado a una región de 500 kb que contiene 63 genes anotados. Finalmente, dos colecciones de introgresiones recíprocas fueron desarrolladas, utilizando “Védrantais” y PS, ambos como líneas parentales recurrente y donante, respectivamente. Se efectuaron retrocruzamientos recurrentes en las dos direcciones y se realizó una selección asistida por marcadores en cada generación, para seleccionar tanto la introgresión diana como el fondo genético deseado. Las colecciones actuales, que cubren el 95% del genoma de la línea parental donante, están formadas por 38 líneas de introgresión. Hemos realizado un fenotipado preliminar que ha permitido validar algunos de los QTLs mapeados en la población de RILs. Además, dos familias segregantes de líneas de introgresión con el fondo genético de PS se han usado para el mapeo fino de ETHQV8.1, permitiendo reducir la región a un intervalo de 150 kb que contiene 14 genes candidatos.<br>Melon (Cucumis melo L.) is an important crop worldwide, with a production of around 31 million tons during 2016. Although traditionally breeding programs have been focused on agronomic traits, fruit quality has become a main goal recently. Fruit quality is a complex concept, including diverse traits related to fruit appearance, nutritional and organoleptic traits. Many of these traits are associated to fruit ripening, which is the process that the fruit undergoes to become edible to promote seed dispersal. Fruits are classified according to their ripening behavior into climacteric, when the plant hormone ethylene is synthesized in an autocatalytic way at the onset of ripening, and non-climacteric, in which ethylene has not a major role. The main goal of this work was to study the genetic basis of fruit quality and fruit ripening in melon. We have developed a Recombinant Inbred Line (RIL) population from a cross between two elite cultivars, “Védrantais”, highly climacteric, and “Piel de Sapo”, non-climacteric. The phenotypic diversity in fruit quality and ripening-associated traits, including ethylene production, has been thoroughly studied. A high-density genetic map was constructed using SNPs and INDELs obtained through a genotyping-by-sequencing experiment. A first QTL mapping experiment revealed five major genes and 33 QTLs governing fruit appearance (flesh and rind color, presence of sutures, mottled rind), fruit morphology, sugar content and seed weight. A second QTL mapping experiment identified 14 QTLs modifying ethylene production and ripening-associated traits, as chlorophyll degradation and abscission layer formation. Among them, we highlight a major QTL, ETHQV8.1, involved in ethylene production that was affecting almost all the studied traits, located in a 500-kb interval in chromosome VIII. In order to genetically dissect the fruit ripening process in melon, in addition to the mentioned RIL population, we studied a climacteric near-isogenic line, 8M35, with “Piel de Sapo” background and containing an introgression from the exotic accession PI 161375. 8M35 carries a QTL, ETHQB3.5, delimited in a region of 5 Mb in chromosome III. A positional cloning strategy was followed to fine map ETHQB3.5, generating a diverse set of subNILs. After multiple evaluations of different subNILs, we determined that at least two different genetic factors should be involved in triggering climacteric ripening in 8M35. One of them, named ETHQB3.5.1, which is responsible for the major part of the variation, was delimited to a 500-kb region containing 63 annotated genes. Finally, two reciprocal introgression line (IL) collections were developed, using both “Védrantais” and “Piel de Sapo” as recurrent and donor parental lines, respectively. Recurrent backcrosses were performed in both directions and marker-assisted selection was performed in each generation to select both the target introgressions and the desired background. The current IL collections, covering approximately 95% of the donor parental genome, are formed by 38 ILs. We performed a preliminary phenotyping that allowed to validate some of the QTLs mapped in the RIL population for both fruit quality and fruit ripening traits. In addition, two segregating families of ILs with “Piel de Sapo” background were used to fine map ETHQV8.1, allowing to narrow down the region to a 150-kb interval containing 14 candidate genes. As a summary, this PhD thesis has contributed to improving our knowledge about the genetics of fruit quality and particularly fruit ripening in melon, proposing some important QTLs that will be further explored in the future. Our work suggests that climacteric behavior in melon is a complex and quantitative trait controlled by polygenic inheritance, rather than a qualitative class as described traditionally in the literature.

A number of methods for the analysis of free amino acids in melon fruit have been evaluated experimentally. Analysis of their tBDMS derivatives by GC (gas chromatography) was found to be the most suitable for the mix of free amino acid found in the melon matrix. It affords good yields of amino acid derivatives with excellent gas chromatographic properties and characteristic mass spectra. The single-step derivatization procedure is highly reproducible and allows simultaneous analysis of asparagine and glutamine together with their corresponding acids. Changes in amino acids, sugars, the principal acids, volatiles and minerals in the free form were studied in the fruit mesocarp during development, ripening and storage of the fruits. Sucrose was the principal sugar, absent in young fruit but showing a dramatic increase during ripening while the levels of fructose and glucose remained constant during the whole course of fruit growth or slightly decreased during ripening and storage. The quantitative determination of 22 free amino acids was achieved by GC analysis using the method developed. Total aroma volatiles were determined using a headspace-gas chromatographic technique. They increased and reached a maximum value just before fruit full slip. Most of the esters characteristic of melon aroma were absent in young fruit but developed at the ripening stage. Changes in the quantities of mineral nutrients present in the fruits were determined by ICP-AES analysis. The concentrations of most elements increased thoughout the fruit development except for Ca which decreased markedly and Cu which decreased during early growth then fluctuated around lower values later in the development stage. All of the above changes can be related to the metabolic activity during fruit growth and maturation. Statistical analysis showed changes in TV, TSS, TS, pH, some free amino acids and some minerals were strongly correlated.<br>Master of Science (Hons)

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

Several experiments were conducted to determine: the influence of canopy position, girdling, and defoliation on nectar production; whether instantaneous light measurements yield reliable estimates of cumulative seasonal light levels within the canopy; and the effect of the canopy light environment on spur leaf physiology and fruit quality. Defoliation of nongirdled flowering spurs had no effect on nectar production or composition, while defoliation of girdled spurs n~duced nectar sugar concentration by 24%. Canopy position had no influence on nectar production or composition. At full bloom there were differences in photosynthe~tic potential of spur leaves from different canopy positions. Exterior leaves had a greater maximum photosynthetic rate and an unique photosynthetic light response curve compared to the intermediate and interior leaves. Differences among positions persisted throughout the season. Stomatal conductance, specific leaf weight, dark respiration, and light levels were greater for the exterior leaves throughout the season. Instantaneous light measurements made on a single uniformly overcast day after the canopy was fully-developed (average of four times during the day) provided reliable estimates (predictive R2 > 0.90, n = 30) of total cumulative seasonal photosynthetic photon density (PPD). There was a I-to-l relationship between instantaneous and cumulative PPD after canopy development was complete providing both measures were expressed as a percentage. The relationships were equal over multiple dates for two consecutive years. Cloudless conditions provided poor estimates (predictive R2 = 0.49 to 0.80, n = 30). Light environment and harvest date influenced fruit quality characteristics within the canopy. Fruit red color, intensity of red color, and soluble solids concentration were all positively related to light level, with the highest R 2 on the early harvest dates. Fruit weight, firmness, length/ diameter ratio, starch index, and seed number were not consistently influenced by the light environment. The number of hours above an average photosynthetic photon flux density threshold of 250 I-£mol. m-2• sec'! explained slightly more of the variation in fruit quality characteristics than any other expressions of light.<br>Ph. D.

A number of methods for the analysis of free amino acids in melon fruit have been evaluated experimentally. Analysis of their tBDMS derivatives by GC (gas chromatography) was found to be the most suitable for the mix of free amino acid found in the melon matrix. It affords good yields of amino acid derivatives with excellent gas chromatographic properties and characteristic mass spectra. The single-step derivatization procedure is highly reproducible and allows simultaneous analysis of asparagine and glutamine together with their corresponding acids. Changes in amino acids, sugars, the principal acids, volatiles and minerals in the free form were studied in the fruit mesocarp during development, ripening and storage of the fruits. Sucrose was the principal sugar, absent in young fruit but showing a dramatic increase during ripening while the levels of fructose and glucose remained constant during the whole course of fruit growth or slightly decreased during ripening and storage. The quantitative determination of 22 free amino acids was achieved by GC analysis using the method developed. Total aroma volatiles were determined using a headspace-gas chromatographic technique. They increased and reached a maximum value just before fruit full slip. Most of the esters characteristic of melon aroma were absent in young fruit but developed at the ripening stage. Changes in the quantities of mineral nutrients present in the fruits were determined by ICP-AES analysis. The concentrations of most elements increased thoughout the fruit development except for Ca which decreased markedly and Cu which decreased during early growth then fluctuated around lower values later in the development stage. All of the above changes can be related to the metabolic activity during fruit growth and maturation. Statistical analysis showed changes in TV, TSS, TS, pH, some free amino acids and some minerals were strongly correlated.

The purpose of this thesis was to research some innovative post-harvest techniques with potential to extend the shelf-life of berry fruit during storage and enhance their overall quality. Emphasis was given to different packaging system, in particular microperforated film, edible film, and electrostatic spraying of antimicrobial coating. The berry fruits studied were blueberry and strawberry. These fruits were selected because of their increasing worldwide consumption, among the many different types of berries. The application of microperforated polypropylene film to store freshly harvested blueberries, demonstrated the importance of selecting a proper packaging to increase the storage period and maintain the quality attributes of the fruit. The number of microperforations made to the film (1, 10, and 30) created a passive modified atmosphere within the package that led to improvement of firmness and antioxidant activity of the fruit, throughout their storage period. Equilibrium atmosphere within the packaging was achieved after two days of storage and the concentration of gases remained constant for the rest of the storage period. This stable atmospheric condition resulted in an extension of the shelf-life of blueberry for up to 16 days, at 4°C. Strawberry shelf-life extension and quality improvements were obtained by storing the fruit in clamshells that contained strawberry puree edible films infused with carvacrol and methyl cinnamate. The strawberry puree edible films served as matrix for the controlled release of natural antimicrobial’s (Carvacrol and methyl cinnamate) vapors, over time. Fresh strawberries packed in clamshells had an extended shelf life of 10 days, at 10◦C and 90% RH. The released vapors from the strawberry puree edible film extended the strawberry shelf-life by delaying spoilage of the fruit and improved main quality-related attributes, such as firmness and brightness. The natural antimicrobial vapors also increased the total soluble phenolic content and antioxidant activity of the stored strawberry. Besides microbial spoilage, that limits strawberry shelf-life, the presence of foodborne pathogens bacteria that can be carried by the fruit as result of contamination, is another important issue that can lead to serious outbreaks. Antimicrobial edible coatings can be an effective post-harvest technique to assure microbial safety and, at the same time, retain overall quality of the fruit. Antimicrobial alginate coating was developed and optimized using response surface methodology. Antimicrobial activity against Escherichia coli O157:H7 and Botrytis cinerea, as well as physical properties such as viscosity, turbidity and whitish index of the coating were also optimized based on carvacrol and methyl cinnamate concentration. After the optimization, the resulted antimicrobial coating solution was applied on the surface of freshly harvested strawberry fruit using an electrostatic spraying technology. This technology presented unique advantage with regard to transfer efficiency and evenness application of the antimicrobial coating solution. The antimicrobial coating application led to a significant increase on strawberry shelf-life. Additionally, the strawberry coated using the electrostatic spraying technology presented a significant reduction of visible decay of four days compared to not-coated fruit, and of one day compared to fruit coated with conventional spray method. Moreover, the firmness and color of the strawberries were improved by coating the fruit using the electrostatic spraying technology. Therefore, electrostatic spraying could be considered a potential technology for the commercial application of liquid coating to extend the shelf-life and improve the post-harvest quality of strawberry and other perishable fruits.<br>Questa tesi è stata volta alla ricerca di alcune tecniche innovative da adottare nel post-raccolta per la conservazione di piccoli frutti, al fine di allungarne la shelf-life e, allo stesso tempo, migliorarne le caratteristiche qualitative. Particolare attenzione è stata posta allo sviluppo e utilizzo di diversi tipi di confezionamento (packaging), in particolare film micro perforati, film edibili, e coating edibili applicati mediante tecnologia spray elettrostatica. Fragole (Fragaria x ananassa) e mirtilli (Vaccinium), tra i diversi tipi di piccoli frutti disponibili sul mercato, sono stati selezionati come modelli di studio a causa del loro crescente consumo globale e importanza economica. Nel primo studio, film in polipropilene micro perforati sono stati utilizzati per la conservazione di mirtilli freschi. La selezione di tali film ha evidenziato l’importanza di utilizzare un packaging opportuno (in base alle caratteristiche ambientali e del prodotto) al fine di allungare il periodo di conservazione del frutto mantenendo allo stesso tempo ottimali caratteristiche qualitative. Le tre diverse intensità di micro perforazioni (1, 10, e 30, create mediante tecnologia laser e dal diametro di 0,1 mm) hanno originato un’ atmosfera modificata passiva all’interno della confezione dovuta alla respirazione del frutto stesso. Tale atmosfera ha causato un miglioramento della consistenza dei mirtilli e un sostanziale incremento dell’attività antiossidasica durante tutto il periodo di confezionamento. All’interno delle confezioni l’equilibrio atmosferico, tra ossigeno consumato ed anidride carbonica prodotta durante il processo di respirazione, è stato ottenuto dopo due giorni di conservazione e mantenuto tale per tutto il periodo di conservazione. Questa particolare condizione di stabilità atmosferica ha determinato un allungamento della shelf-life dei mirtilli fono a 16 giorni a 4 °C. Il secondo studio ha visto l’ottenimento dell’estensione della shelf-life e il miglioramento delle caratteristiche qualitative di fragole fresche, utilizzando delle confezioni commerciali in cui erano stati applicati film edibili. Tali film ottenuti da purè di fragole erano stati arricchiti con carvacrolo e metile cinammato, due oli essenziali naturali dal potere antimicrobico. Il film edibile, fungendo da vettore, ha permesso il rilascio graduale dei vapori degli oli essenziali nel tempo. La shelf-life delle fragole conservate con questo packaging a 10 °C e con il 90% di umidità relativa è aumentata fino a 10 giorni, grazie al potere antimicrobico dei vapori degli oli essenziali che hanno ritardato lo sviluppo microbico sulla superficie del frutto, di conseguenza aumentando anche alcune caratteristiche qualitative come ad esempio la brillantezza e la compattezza. Anche la capacità antiossidasica totale e il contenuto di fenoli è aumentato a causa dell’effetto dei vapori di carvacrolo e metile cinnamato. Lo sviluppo microbico, e in particolare di muffe, è solo uno degli aspetti che limitano il consumo di fragole fresche. Infatti, la presenza di microorganismi patogeni di origine alimentare è molto diffusa soprattutto su prodotti freschi e deperibili come le fragole che non vengono lavate dopo la raccolta e possono fungere da vettore di tali batteri patogeni e causare serie epidemie. Considerando tale problematica, l’utilizzo di coating edibili con azione antimicrobica (direttamente applicati sulla superficie del frutto) possono essere considerati una valida soluzione per garantire sicurezza microbiologica e allo stesso tempo per mantenere inalterate le caratteristiche qualitative del frutto. L’attenzione del terzo studio è stata rivolta allo sviluppo e ottimizzazione di un coating antimicrobico di alginato di sodio utilizzando una collezione di metodi statistici e matematici definiti come response surface methodology (RSM). L’attività antimicrobica nei confronti di Escherichia coli O157:H7 e Botrytis cinerea, e alcune caratteristiche fisiche della soluzione, come ad esempio la viscosità, turbidità e indice del bianco (Wi) sono stati ottimizzati sulla base delle concentrazioni dei componenti antimicrobici selezionati (carvacrolo e metile cinnamato). Dopo l’ottimizzazione e lo sviluppo del coating di alginato, lo stesso coating è stato applicato su fragole fresche utilizzando la tecnologia spray elettrostatica caratterizzata dal vantaggio di creare maggiore resa e uniformità di coating rispetto ad una comune tecnologia spray. L’applicazione di tale coating elettrostatico ha reso possibile una estensione della shelf-life delle fragole trattate e una significativa e visibile riduzione di muffe presenti sui frutti pari a quattro giorni di ritardo quando paragonato alle fragole non trattate e un giorno nei confronti delle fragole trattate con una comune tecnologia spray. Inoltre, la compattezza e il colore delle fragole è migliorata durante il periodo di conservazione quando il metodo elettrostatico è stato utilizzato.

Quantify the magnitude, sources and distribution of variation in fruit quality traits within kiwifruit populations and identify opportunities for the management of this variation. Near-infrared (NIR) grading was used as a tool for monitoring fruit quality, and measurements combined with orchard/vine information to investigate opportunities for the management of the variation in fruit quality traits with a particular focus on fruit DM. NIR enabled non-destructive assessment of the quality characteristics of individual fruit from 96 commercial orchards, comprising 550 fruit-lines, across four consecutive seasons, resulting in a dataset of measurements made on 146.7 million individual fruit. The distribution of quality traits within fruit populations and the relationships between quality traits were examined. The spatial component of variation in fruit quality was investigated to assess the potential for zonal management practices. Finally, the effects of growth temperatures on fruit quality were studied. Significant variation in fruit quality was observed between-seasons, between-orchards, and between-vines within an orchard. From comparison of CVs between quality traits, cropload was more variable than fruit weight which varied more than fruit DM, independent of the production scale considered (between-orchard or between-vine). Across a hierarchy of fruit populations (individual vine, fruit-line and orchard), the majority of fruit quality distributions demonstrated significant deviations from normality. However, departures from normality can be tolerated for estimation of the proportion of fruit with specific quality criteria. The sources of variation in fruit weight and DM populations were investigated at both a between-orchard scale and a within-orchard scale. Between-orchard variation was significant, however, the majority of variation occurred within-fruitlines, within-orchards and within seasons. The within-fruitline component of variation was investigated separately. Both between-vine and within-vine variation were significant, but within-vine variation was dominant. The focus of management should be on reducing variation occurring within-fruitlines within-orchards, which is largely attributable to variation occurring within the individual vine. Higher croploads per vine have negative consequences for fruit weight but variable effects on DM. Increasing croploads reduce both FW and DW allocations for each fruit, therefore the effect of cropload on DM is dependent on the relative reductions in FW and DW. The DW allocations to fruit are not limited by DW production, at least up to the croploads observed in this study (≤65 fruit m-2). The potential for zonal management was investigated. Variation in fruit quality characteristics between-orchards across the Te Puke growing region, and between-vines within an individual orchard area were investigated using geostatistics. A spatial component to variation was identified both between-orchard and between-vine. However, the effect of spatial variation was diluted by that of non-spatial variation and therefore, zonation between orchards or between areas within-orchards should not be where the effort in managing variation is concentrated. Orchard altitude correlated with some aspects of fruit quality. Mean fruit weight declined 0.5g and within-orchard variation in fruit weight declined 0.25 units with a 25m increase in orchard altitude. Mean fruit DM was independent of orchard altitude and within-orchard variability in DM declined 0.023 units per 25m increase in orchard altitude. Differences in orchard altitude equated with differences in growth temperatures. Warm spring and cool summer temperatures favour the growth of high DM fruit. The effects of spring temperatures on canopy development and maturation were investigated to elucidate potential physiological mechanisms for temperatures effects on fruit growth. Higher spring growth temperatures increased the rate of total leaf area development and promoted development of leaf photosynthesis. Higher spring growth temperatures favoured a more positive carbon balance, which has beneficial effects on the development of fruit quality characteristics. Post-harvest, the traditional practice of grading fruit into count sizes generally also segregates for DM, and large count size fruit will often have higher DM than small sized fruit. Between fruit populations, a positive correlation was identified between fruit DM and acidity; therefore, segregation of the inventory by DM will also segregate for acidity. High DM fruit are also more acidic with a higher, more favourable brix/acid ratio when ripe. It is recommended that fruit DM status be managed in the inventory, not by maturity area as is the current practice, but by groups of similar count sizes within maturity areas.

The aim of this research was to develop a new harvest maturity index for highly coloured stone fruit that is not affected by seasonal or climatic factors. The judgement of commercial maturity is difficult with some cultivars of stone fruit because they develop intense skin pigmentation several days before they are ripe. Studies of the changes of the physiochemical and physiological parameters associated with ripening confirmed that no single measurement is suitable for the assessment of harvest maturity in the Japanese type plum cultivars(Prunus salicina Lindl). Two distinct patterns of ripening behaviour were identified. The cool storage (0 degrees Centigrade) responses of fruit harvested at three stages of maturity were examined. Total soluble proteins were extracted and separated from fruit during maturation and ripening using 2-dimensional gel electrophoresis. At least three proteins were first detected in fruit at optimum commercial harvest maturity. Since Gulfruby, Beauty and Rubyred (Japanese type plum cultivars) accumulated similar concentrations of aminocyclopropane-1-carboxylic acid(ACC), it was suggested that the suppressed-climacteric phenotype is the result of an impaired ability of the fruit to convert this compound to ethylene<br>Doctor of Philosophy (PhD) (Ph.D.)

Stone fruits are highly perishable due to their sensitivity to ethylene which limit their domestic and international trade. Different formulations of the anti-ethylene compounds 1H-cyclopropabenzene and 1H-cyclopropa[b]naphthalene were investigated to manage ethylene, extend postharvest life and maintain fruit quality. Fumigation and spray solutions containing ethanol prevented the deleterious effects of ethylene and maintained postharvest fruit quality of stone fruits. The development of spray solutions will allow these compounds to be used in future open-field applications.

Thesis (PhD(Agric))--Stellenbosch University, 2013.<br>ENGLISH ABSTRACT: The aim of this study was to develop non-destructive methods to predict external and internal quality of citrus fruit. A critical review of the literature identified presymptomatic biochemical markers associated with non-chilling rind physiological disorders. The prospects for the use of visible to near infrared spectroscopy (Vis/NIRS) as non-destructive technology to sort affected fruit were also reviewed. Initial studies were conducted to determine the optimum condition for NIRS measurements and to evaluate the accuracy of this technique and associated chemometric analysis. It was found that the emission head spectroscopy in diffuse reflectance mode could predict fruit mass, colour index, total soluble solids, and vitamin C with high accuracy. Vis/NIRS was used to predict postharvest rind physico-chemical properties related to rind quality and susceptibility of ‘Nules Clementine’ to RBD. Partial least squares (PLS) statistics demonstrated that rind colour index, dry matter (DM) content, total carbohydrates, and water loss were predicted accurately. Chemometric analysis showed that optimal PLS model performances for DM, sucrose, glucose, and fructose were obtained using models based on multiple scatter correction (MSC) spectral pre-processing. The critical step in evaluating the feasibility of Vis/NIRS was to test the robustness of the calibration models across orchards from four growing regions in South Africa over two seasons. Studies on the effects of microclimatic conditions predisposing fruit to RBD showed that fruit inside the canopy, especially artificially bagged fruit, had lower DM, higher mass loss, and were more susceptible to RBD. The study suggested that variations in microclimatic conditions between seasons, as well as within the tree canopy, affect the biochemical profile of the rind, which in turn influences fruit response to postharvest stresses associated with senescence and susceptibility to RBD. Principal component analysis (PCA) and PLS discriminant analysis (PLS-DA) models were applied to distinguish between fruit from respectively, inside and outside tree canopy, using Vis/NIRS signal, suggesting the possibility of using this technology to discriminate between fruit based on their susceptibility to RBD. Results from the application of optical coherence tomography (OCT), a novel non-destructive technology for imaging histological changes in biological tissues, showed promise as a potential technique for immediate, real-time acquisition of images of rind anatomical features of citrus fruit. The study also demonstrated the potential of Vis/NIRS as a non-destructive tool for sorting citrus fruit based on external and internal quality.<br>AFRIKAANSE OPSOMMING: Die studie het ten doel gestaan om nie-destruktiewe meeting metodes te toets en ontwikkel wat die interne en eksterne-kwaliteit van sitrusvrugte kan voorspel. In ʼn litratuuroorsig is biochemies verandering in die skil en wat geassosieer word met die ontwikkeling van fisiologies skildefekte geïdentifiseer, asook is die moontlikheid ondersoek om Naby Infrarooi spektroskopie (NIRS) as ‘n nie-destruktiewe tegnologie te gebruik om vrugte te sorteer. Eerstens was die optimale toestande waarby NIRS meetings van sitrusvrugte geneem moet word asook die akkuraatheid van die toerusting en chemometrika data-ontleding beproef. Daar is gevind dat die uitstralings-kop spektrofotometer in diffusie-weerkaatsings modus vrugmassa, skilkleur, totale opgeloste stowwe asook vitamien C akkuraat kan voorspel. Daarna van NIRS gebruik om na-oes fisies-chemiese eienskappe wat verband hou met skilkwaliteit en vatbaarheid vir skilafbraak van ‘Nules Clementine’ mandaryn. Deur gebruik te maak van “Partial least squares” (PLS) statistieke was gedemonstreer dat die skilkleur, droë massa (DM), totale koolhidrate en waterverlies akkuraat voorspel kon word. Chemometriese analises het ook getoon dat optimale PLS modelle vir DM, sukrose, glukose en fruktose verkry kan word deur modelle te skep wat gebaseer is op “Multiple scatter correction” (MSC) spektrale voor-verwerking. ʼn Belangrike stap in die ontwikkeling van NIRS gebaseerde indeling is om die robuustheid van die kalibrasiemodelle te toets en was gedoen deur vrugte te meet en sorteer van vier boorde en oor twee seisoene. ʼn Verder eksperiment om die impak van mikroklimaat op die skil se vatbaarheid vir fisiologiese defekte te ontwikkel het getoon dat vrugte wat binne in die blaardak ontwikkel (lae vlakke van sonlig) ʼn laer DM, hoër gewigsverlies het en was ook meer vatbaar vir skilafbraak. Die resultate dui daarop dat verskille in mikroklimaat oor die seisoen asook in die blaardak die skil se biochemiese profiel beïnvloed, wat lei tot ʼn negatiewe reaksie op na-oes stres en verhoogde voorkoms van fisiologiese skilafbraak. Die ontwikkelde “Principal component analysis” (PCA) en PLS-diskriminant analise modelle was daarna suksesvol toegepas om vrugte te skei na NIRS meetings, op die basis van vrugpossies in die blaardak. Nuwe, nie-destruktiewe tegniek, nl. “Optical coherence tomography” (OCT) was suksesvol getoets as manier om ʼn fotografiese beeld te skep van histologiese veranderinge in die skil. Die resultate dui op die potensiaal van die onontginde tegnologie om intak biologiese-materiaal te analiseer. Hierdie studie het getoon dat daar wesenlike potensiaal is om NIRS verder te ontwikkel tot ʼn tegnologie wat gebruik kan word om vrugte te sorteer gebaseer op eksterne (skil) asook interne (pulp) eienskappe

La maduixa cultivada, Fragaria x ananassa, és un cultiu mundialment important. Les seves fruites s’ aprecien pel balanç entre la dolçor i la acidesa, i pel seu aroma característic. Malgrat que tradicionalment els programes de millora de maduixa estaven enfocats en el rendiment i la resistència a les malalties, actualment, l’interès per la qualitat de la fruita s’ha vist augmentat. La maduixa cultivada és una espècie allo-octoploid (2n = 8x = 56) i el seu genoma és altament diploiditzat. La naturalesa poliploide augmenta la dificultat per analitzar l’herència genètica dels caràcters quantitatius. El coneixement que es té sobre l’espècie model F. vesca es pot transferir fàcilment a la maduixa cultivada, ja que el seu genoma és un dels subgenomes de les espècies octoploides. Amb l’ objectiu de determinar l’herència de l’ aroma de la maduixa i d’altres caràcters de la qualitat de la fruita, hem estudiat amb profunditat dues poblacions de millora, una F1 i una F2. La població F1 (‘FC50xFD54’ ) s’ha obtingut amb l’ encreuament de les línies de millora ‘FC50’, seleccionada per l’ aroma a maduixa del bosc, i ‘FD54’ , seleccionada per l’ aroma afruitat. Hem construït un mapa genètic saturat per a la població ‘FC50xFD54’ amb 1495 marcadors polimòrfics, del xip IStraw35k, agrupats en 28 LGs i repartits en 3451cM. La comparació del mapa mostra una alta col·linealitat entre les posicions dels marcadors del mapa genètic del ‘FC50xFD54’ amb el mapa consens de F. x ananassa i amb els genomes diploide i octoploide de Fragaria. A més, hem millorat el mapa genètic de la població F2 (‘21AF’ ), obtinguda de l’ encreuament entre les línies d’ elit ‘Camarosa’ , seleccionada per la qualitat de la fruita i ‘Dover’ , seleccionada per ser robusta. El mapa resultant està compost per 7977 marcadors polimòrfics, agrupats en 28 LGs i cobreix una longitud de 2056cM. La variació fenotípica de l’ acumulació dels compostos volàtils (VOCs), gust (acidesa i SSC) i caràcters d’ aparença com la forma, el color o la fermesa s’ ha estudiat detalladament en les fruites madures d’ aquestes dues poblacions en diferents collites. L’ anàlisi de la segregació i de la correlació entre aquests caràcters han permès la detecció de possibles caràcters co-regulats i l’ anàlisi de QTL han permès localitzar centenars de regions que expliquen la variació observada. Els compostos orgànics majoritaris que contribueixen en la preferència dels consumidors són els sucres, els àcids i els VOCs. S’ han identificat un total de 58 VOCs en ‘FC50xFD54’ i s’han localitzat 19 QTLs estables. D’entre aquests, 22 QTLs amb alta estabilitat estan relacionats amb els compostos volàtils claus (KVCs) que són objectiu d’ alguns programes de millora de l’ aroma. A més, alguns d’ aquests QTLs pels KVCs han estat validats en la població ‘21AF’ . Ressaltem la detecció d’ un QTL pels terpens localitzat al LG3B, diferents QTLs per èsters als LG1A, LG4B, LG6A i LG7D, un QTL pel metil antranilat al LG7A i un altre per la γ-decalactona al LG3D. Les anàlisis del sabor i de l’aparença han permès localitzar un total de 77 QTLs estables a la població ‘FC50xFD54’ i de 31 QTLs a la població ‘21AF’ . Ressaltem un QTL pel color intern trobat al LG1A i dos QTLs per la forma de la fruita localitzats al LG4C i LG6D. La població ‘FC50xFD54’ segrega per un allargament del coll no desitjat, mapant dos QTLs als LG3A i LG4B. Aquesta tesi ha contribuït en la millora del coneixement genètic sobre la qualitat de la fruita, específicament l’aroma, el gust i l’ aparença. A més, els SNPs seleccionats lligats a un caràcter d’ interès podrien utilitzar-se en MAS per satisfer la demanda dels consumidors.<br>La fresa cultivada, Fragaria x ananassa, es un cultivo importante mundialmente. Sus frutas son apreciadas por su sabor, balance entre dulzura y acidez y por su característico aroma. Tradicionalmente, los programas de mejora de fresa han estado enfocados en la mejora del rendimiento y de la resistencia a enfermedades, pero actualmente, el interés en la calidad de la fruta se ha incrementado. La fresa cultivada es una especie allo-octoploide (2n = 8x = 56) y su genoma está altamente diploidizado. Su naturaleza poliploide dificulta el análisis de la herencia genética de los caracteres cuantitativos. El conocimiento en la especie modelo F. vesca se puede transferir fácilmente a la fresa cultivada, ya que su genoma es también uno de los subgenomas en las fresas octoploide. Con el objetivo de conocer la herencia del aroma y de otros caracteres de la calidad de la fruta, hemos estudiado en profundidad dos poblaciones de mejora, una F1 y una F2. La población F1 (‘FC50xFD54’) fue obtenida del cruzamiento entre las líneas de mejora ‘FC50’, seleccionada por su aroma a fresa del bosque, y ‘FD54’, seleccionada por su aroma afrutado. Hemos construido un mapa genético saturado para esta población con 1495 marcadores polimórficos del chip IStraw35k agrupados en 28 LGs y repartidos en 3451cM. La comparación de los mapas muestra una alta colinealidad entre las posiciones de los marcadores del mapa genético ‘FC50xFD54’ y del mapa consenso de F. x ananassa y también con los genomas diploide y octoploide de Fragaria. Además, hemos mejorado el mapa genético de la población F2 (‘21AF’), obtenida del cruzamiento entre las líneas ‘Camarosa’, seleccionada por la calidad de su fruta, y ‘Dover’, por ser robusta. El mapa resultante está compuesto por 7977 marcadores polimórficos, agrupados en 28 LGs y cubriendo 2056cM. La variación fenotípica de la acumulación de los compuestos volátiles (VOCs), gusto (acidez y SSC) y caracteres de apariencia como la forma, el color o la firmeza en las frutas maduras de las dos poblaciones ha sido estudiada detalladamente en diferentes cosechas. Los análisis de la segregación y correlación entre estos caracteres han permitido la detección de posibles caracteres co-regulados y los análisis de QTL han localizado cientos de regiones explicando la variación observada. Los compuestos orgánicos que contribuyen en la preferencia de los consumidores son los azucares, los ácidos y los VOCs. Un total de 58 VOCs fueron identificados en la población ‘FC50xFD54’ localizando 179 QTLs estables. De entre estos QTLs, 22 con alta estabilidad fueron relacionados con los compuestos volátiles clave (KVCs), objetivo de algunos programas de mejora. Además, algunos de estos QTLs para los KVCs fueron validados en la población ‘21AF’. Resaltamos la detección de un QTL para los compuestos terpenoides localizado en LG3B, diferentes QTLs para compuestos de tipo éster en LG1A, LG4B, LG6A y LG7D, un QTL para metil antranilato en LG7A y otro para γ-decalactona en LG3D. Los análisis del sabor y la apariencia han reportado un total de 77 QTLs estables en la población ‘FC50xFD54’ y 31 QTLs en la población ‘21AF’. Resaltamos un QTL para el color interno encontrado en LG1A y dos QTLs para la forma de la fruta localizados en LG4C y LG6D. La población ‘FC50xFD54’ segregaba por un carácter no deseado, el alargamiento del cuello, y el análisis de QTLs ha mapeado QTLs en LG3A y LG4B. Esta tesis ha contribuido a mejorar el conocimiento genético sobre la calidad de la fruta, específicamente el aroma, el gusto y la apariencia. Además, los SNPs seleccionados ligados a un carácter de interés podrían ser usados en la selección asistida por marcadores (MAS) para satisfacer la demanda de los consumidores.<br>Cultivated strawberry, Fragaria x ananassa, is an important crop cultivated worldwide. Its fruits are appreciated for their balance between sweetness and acidity and for their characteristic aroma. Although, traditionally, strawberry breeding programs were essentially focused on yield improvement and disease resistance, currently, there is also an interest in improving some fruit quality traits. Cultivated strawberry is allo-octoploide (2n = 8x = 56) and its genome is highly diploidised. Its polyploid nature increases the difficulty to analyse the genetic heritability of quantitative traits. The knowledge of the model species F. vesca can be easily transferred to cultivated strawberry, since its genome constitute one of its subgenomes. In order to elucidate the heritability of strawberry aroma and other fruit quality traits, we have studied in depth two breeding populations, an F1 and an F2. The F1 population (‘FC50xFD54’) was produced through a cross between the breeding lines ‘FC50’, selected for its wild strawberry aroma, and ‘FD54’, selected for its fruity aroma. We have constructed a saturated ‘FC50xFD54’ genetic map with 14595 polymorphic markers, from IStraw35k array, grouped in 28 LGs and spanning 3451cM. The maps comparison shows high collinearity between marker position in ‘FC50xFD54’ genetic map and the F. x ananassa consensus map and with the diploid and octoploid Fragaria genomes. Additionally, we improved the genetic map of the F2 population (‘21AF’), derived from a cross between two elite lines ‘Camarosa’, selected for its fruit quality, and ‘Dover’, selected for its robustness. The resulting map is composed of 7977 polymorphic markers grouped in 28 LGs and covers a total length of 2056cM. The phenotypic variability of ripe fruits in these two populations for volatile compounds accumulation (VOCs), taste (acidity and SSC) and appearance traits such as shape, colour and firmness has been thoroughly studied in different harvests. The analysis of segregation and the study of correlation between traits allowed the detection of possible co-regulated traits and the QTL analysis located hundreds of regions that explain the variance of these traits. The main organic compounds contributing to consumer preferences are sugars, acids and VOCs. A total of 58 different VOCs was identified in ‘FC50xFD54’ and 179 stable QTLs were localised. Of these QTLs, 22 presenting high stability were related to key volatile compounds (KVCs) which are target of some aroma breeding programs. Additionally, some of these KVC QTLs were validated in the ‘21AF’ population. We highlight the detection of a QTL for terpene compounds in LG3B, different QTLs for ester compounds in LG1A, LG4B, LG6A and LG7D, a QTL for methyl anthranilate in LG7A and another for γ-decalactone in LG3D. The analysis of taste and appearance traits reported a total of 77 stable QTLs in the ‘FC50xFD54’ population and 31 QTLs in the ‘21AF’ population. We highlight an internal colour QTL found in LG1A and two fruit shape QTLs in LG4C and LG6D. ‘FC50xFD54’ population segregated for an undesirable neck phenotype whose QTLs were mapped in LG3A and LG4B. The aim of this thesis was to increase the genetic knowledge of fruit quality, specifically aroma, taste and appearance traits. Furthermore, the selected SNPs linked to a desired trait could be applied in marker assisted selection (MAS) to satisfy the consumer demand.<br>Universitat Autònoma de Barcelona. Programa de Doctorat en Biologia i Biotecnologia Vegetal

[EN] Until recently, the genetic improvement of tomato (Solanum lycopersicum) was focused in agronomic traits, such as yield and biotic or abiotic stresses; therefore the interest in tomato fruit quality is relatively new. The tomato fruit surface can be considered both an agronomic trait as well as a quality trait, because it has an effect on consumer impression in terms of color and glossiness but also it underlies the resistance/sensitivity to cracking or water loss with consequences on fruit manipulation (e.g. transport and processing). The cuticle is deposited over the cell wall surrounding the epidermal cells and it is the first barrier in the plant-environment interface. The cuticle composition includes two main groups of metabolites: cuticular waxes and cutin. Other metabolites can be founded into the cuticle matrix, as triterpenoids and flavonoids. Those minor cuticular components are involved in the correct functionality of the cuticle. Understanding cuticle biosynthesis and genetic regulation requires the development of fast and simple analytical methodologies to study those specialized metabolites using large populations (e.g. mutant collections or introgression lines), together with the identification of genes and genomic regions responsible of their production. This thesis aims to contribute to our understanding of the molecular programs underlying tomato fruit quality by providing: i) a general protocol to profile cuticular waxes in different species, including tomato; ii) a QTL map for cuticular composition (i.e. cuticular waxes and cutin monomers) using the Solanum pennellii introgression line population; iii) a detailed protocol of the reverse genetic tool so-called Fruit-VIGS to assist in the study of gene function in tomato fruit; and iv) a thorough characterization of the first null allele for the transcription factor SlMYB12 (i.e. Slmyb12-pf) in tomato fruit which provides new insights into the regulation of the flavonoid biosynthetic pathway in the fruit peel by high resolution mass spectrometry and RNA-Seq approaches.<br>[ES] Hasta hace poco, la mejora genética del cultivo del tomate (Solanum lycopersicum) había estado centrada principalmente en caracteres agronómicos, como la productividad y la resistencia a estreses, tanto bióticos como abióticos. Así, el interés en la calidad del fruto de tomate es relativamente reciente. La superficie del fruto del tomate puede considerarse tanto un carácter agronómico como de calidad, pues influye en la primera impresión de los consumidores en términos de color y brillo, así como también en los procesos de resistencia o sensibilidad a la rotura ('cracking') o a la pérdida de agua. Estos factores determinan el aspecto del fruto y condicionan atributos relacionados con su manipulación (transporte y procesado). La cutícula se deposita sobre la pared celular de las células epidérmicas y es la primera barrera que interacciona con el ambiente. Está constituida por dos grandes tipos de metabolitos: las ceras cuticulares y la cutina. Otros metabolitos pueden aparecer embebidos en la matriz cuticular, como es el caso de los triterpenoides y los flavonoides. Estos metabolitos contribuyen a la correcta funcionalidad de la cutícula. La compresión de la biosíntesis y regulación génica de la cutícula requiere del desarrollo de metodologías de análisis sencillas y rápidas para el estudio de estos metabolitos especializados en grandes poblaciones (colecciones de mutantes o líneas de introgresión), así como para la identificación de genes y regiones génicas responsables de la producción y acumulación de dichos compuestos, pudiendo ser muy útiles para implementar programas de mejora de la calidad del tomate. El objetivo de esta tesis es contribuir a la comprensión sobre los programas moleculares subyacentes a la calidad del fruto de tomate, proporcionando: i) un protocolo general de análisis del contenido de ceras cuticulares en diferentes especies, incluyendo el tomate; ii) un mapa de QTL de la composición cuticular (incluyendo ceras y monómeros de cutina) obtenido con la población de líneas de introgresión de Solanum pennellii; iii) un protocolo detallado de uso de la herramienta de genética reversa Fruit-VIGS con el que realizar estudios de funciones génicas en fruto de tomate; y iv) una minuciosa caracterización de un nuevo alelo nulo del factor de transcripción SlMYB12 (Slmyb12-pf) en fruto de tomate, proporcionando nueva información sobre la regulación de la ruta biosintética de los flavonoides en la piel del fruto, utilizando espectrometría de masas de alta resolución y de nuevas tecnologías de secuenciación.<br>[CAT] Fins fa poc de temps, la millora genètica de la tomata (Solanum lycopersicum) anava dirigida fonamentalment als caràcters de tipus agronòmic, com la productivitat i la tolerància a estressos biòtics o abiòtics, resultant que l'interés per la qualitat dels fruits és relativament nou. La superfície de la tomata pot ser considerada tant com un caràcter agronòmic com un de qualitat, ja que és l'aspecte de la superfície del fruit el que confereix al consumidor la primera impressió de color, brillantor, però és també la pell del fruit la responsable de la diferent susceptibilitat del fruit a desenvolupar clevills o que el fruit sofrisca més o menys pèrdues d'aigua, tot tenint importants conseqüències en la manipulació (i.e. transport i processament del fruit). La cutícula és dipositada per sobre de la paret cel·lular que envolta la capa de cèl·lules epidèrmiques i constitueix la primera barrera en la interfase planta-medi ambient. La composició de la cutícula presenta dos grups principals de metabòlits: les ceres i la cutina. També es poden trobar altres metabòlits els triterpenoids i el flavonoids. Aquests darrers components cuticulars menors són implicats en el correcte funcionament de la cutícula. Per tal de comprendre la biosíntesi i la regulació genètica de la cutícula cal desenvolupar tecnologies analítiques senzilles i rapides que permeten estudiar aquests metabòlits especialitzats en poblacions grans de plantes (i.e. Col·leccions de mutants o de línies d'introgressió), a més de la identificació de gens i regions genòmiques que són responsables de la seua producció. Aquesta tesi té com a objectiu contribuir a millorar la nostra comprensió dels programes moleculars que afecten determinats aspectes de la qualitat de la tomata mitjançant els següents objectius: i) proporcionar un protocol general per obtenir perfils de ceres cuticulars en diferents espècies, inclosa la tomata; ii) obtenir un mapa de QTL per a la composició cuticular (i.e. ceres cuticulars i monòmers de cutina) mitjançant la utilització de la població de línies d'introgressió de Solanum pennelli; iii) descriure amb detall el protocol d'una eina de revers genètica denominada Fruit-VIGS que resulta molt adequada per estudiar funció gènica a la tomata; y iv) fer una caracterització exhaustiva del primer al·lel nul del factor de transcripció SlMYB12 (ie. Slmyb12-pf) en tomata la qual proporciona informació nova sobre la regulació de la ruta de biosíntesi de flavonoides en la pell de la tomata mitjançant espectrometria de masses d'alta resolució i RNAseq.<br>Fernández Moreno, JP. (2015). TOMATO FLESHY FRUIT QUALITY IMPROVEMENT: CHARACTERIZATION OF GENES AND GENOMIC REGIONS ASSOCIATED TO SPECIALIZED METABOLISM IN TOMATO FLESHY FRUIT [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/55505<br>TESIS<br>Premiado

Tomato is an important food crop and a model for fleshy fruit development. The process of fruit ripening involves changes in chemical composition and in particular the accumulation of sugars, organic, amino acids and carotenes. The research described in this thesis aimed to identify key regulatory aspects associated with the accumulation of the major acids in tomato fruit by analysis of introgression lines resulting from a cross between a cultivated variety, Solanum lycopersicum, and a wild progenitor species, Solanum pennellii. Line 2-5 showed increases in citrate, malate, aspartate and glutamate in fruit grown under greenhouse conditions. The genetic differences between line 2-5, its overlapping lines, sub-introgression lines and the recurrent parent were used to link the metabolite phenotypes to smaller chromosomal regions. This analysis suggested multiple epistatic loci control fruit metabolite accumulation. Investigation of the biochemical differences between line 2-5 and the recurrent parent revealed that organic and amino acid accumulation did not dependent upon increased TCA cycle capacity. Regulation at the metabolic level was identified for citrate accumulation with changes in cytosolic aconitase in line 2-5. As these metabolites accumulate in the vacuole, tonoplast transport was investigated. Correlation of ATPase-dependent malate influx with altered malate content suggested malate tonoplast transport plays a role in malate accumulation and highlights the importance of vacuolar storage and transport in the regulation of organic and amino acid accumulation.

Thesis(MScEng)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: The SQUID-NMR technique has been increasingly recommended by many researchers as holding a lot of potential, and it is believed it will become an invaluable tool for non-destructive evaluation in the future. Most of its potential is yet to be exploited. Non-destructive quality control of food products is one of the applications where such a system is being tried. Much of the progress that has been made in improving such a system to the present degree of user friendliness and cost effectiveness shows that, with more effort, it would be possible to implement the technology for on-line sorting, and possibly to reduce it down to hand-held devices. The goal was to investigate the feasibility of the internal fruit quality measurements using the NMR technique, and to develop a SQUID system suitable for SQUID-NMR application, intended for a later integration in a full SQUID-NMR system. A working dc SQUID was manufactured on an YBCO (Y Ba2Cu3O7􀀀 ) thin film deposited on a 10 mm x 10 mm MgO substrate. The SQUID was made of microbridge Josephson junctions, patterned by using the double resist laser lithography method, implemented during the course of this manufacturing process. The test of the SQUID showed a non-hysteretic current-voltage characteristic. Under the action of bringing a magnet closer to the SQUID under test, and then retracting it, the modulation of the I-V curve was observed. The critical current of the SQUID was 20 A and the resistance was 5.5 A series of experiments were performed on destructive measurements of the sugar content in table grapes using NMR, in order to evaluate the feasibility of this technique. The total sugars(TSS) measurements of the same samples were carried out by refractometry, chosen as a conventional method for validation. The NMR measurements were evaluated to be 5.4% precise and have an accuracy of 9.3% relative to the refractometry measurements. A further series of experiments were carried out on a high-Tc SQUID-NMR system. A high correlation coefficient (0.85) of the increasing values of the T1 and T2 relaxation times to the decreasing concentration of sugar (sucrose) in water was obtained. Non-destructive measurements T1 and T2 in table grapes suggested a possible prediction of sugar content in table grapes from the values of T1 or T2. This technique also presented many advantages compared to the conventional high field NMR technique, such as the fast measurements that do not require spectral processing, the ease of sample preparation, and its non-destructive nature.<br>AFRIKAANSE OPSOMMING: Die SQUID-NMR tegniek word al hoe meer aanbeveel deur navorsers oor die groot potensiaal, en dit beloof om in die toekoms van onskatbare waarde te wees in nie vernietigende evaluering. Die potensiaal moet grotendeels nog ontgin word, en die nie vernietigende kwaliteitsbeheer van voedselprodukte is een van die toepassings wat hier getoets word. Die vooruitgang tot dusver om die stelsel te verbeter wat die gebruikersvriendelikheid en koste-effektiwiteit betref, toon dat met effens meer moeite dit moontlik sal wees om die tegnologie aan te pas vir lynsortering van vrugte, en om dit dalk ook as handtoestel beskikbaar te stel. Die vooruitgang tot dusver om die stelsel te verbeter wat die gebruikersvriendelikheid en koste-effektiwiteit betref, toon dat met effens meer moeite dit moontlik sal wees om die tegnologie aan te pas vir lynsortering van vrugte, en om dit dalk ook as handtoestel beskikbaar te stel. Die doel is om die uitvoerbaarheid van interne vrugtekwaliteit metings deur hierdie tegniek te ondersoek en om ’n SQUID stelsel te ontwikkel wat gepas is vir SQUIDNMR toepassing, met die doel om dit later in ’n volledige SQUID-NMR stelsel te kan integreer. ’n Werkende GS-SQUID is vervaardig op ’n YBCO dunfilm wat op ’n 10 mm x 10 mm MgO substraat gedeponeer is. Die SQUID is van mikro-brug Josephson aansluitings/ voegvlakke, waarop in die loop van die vervaardigingsproses ’n patroon m et dubbelweerstand laser litografie neergelê is. Toets van die SQUID het ’n niehisterese stroom-spanning as kenmerkend getoon. Die nader bring en terugtrekking van ’n magneet het gelei tot waarneming van die modulasie van die I-V kurwe. Die kritieke stroom van die SQUID was 20 A en die weerstand was 5.5 ohm. ’n Reeks eksperimente is uitgevoer oor vernietigende metings van die suikerinhoud van tafeldruiwe met gebruik van NMR, om die gangbaarheid van hierdie tegniek te evalueer. Totale suikers (TSS) metings van dieselfde monsters is uitgevoer deur refraktometrie, wat gekies is as gebruiklike metode vir geldigheidsbepaling. Die NMR metings is as 5.4% presies/noukeurig evalueer, en met ’n akkuraatheid van 9.3% teenoor die refraktometrie metingsyfers. ’n Verdere reeks eksperimente is uitgevoer op ’n hoë-Tc SQID-NMR stelsel. ’n Hoë korrelasiekoëffisiënt van 0.85 van die toenemende waardes van T1 en T2 ontspantye teenoor die afname in konsentrasie van sukrose in water is waargeneem. Nie-vernietigende metings van T1 eb T2 in tafeldruiwe het gelei tot die moontlikheid van gebruik van hierdie tegniek om suikerinhoud van tafeldruiwe te voorspel. Die tegniek het ook baie voordele getoon in teenstelling met die gebruiklike hoëveld NMR tegniek, onder andere dat hierdie metings vinniger is, nie verdere verwerking van die spektrum benodig nie, die maklike voorbereiding van die monsters en die nie-vernietigende aard van die proses.

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Two experiments were conducted to determine the influence of light on 'Norman' and 'Cresthaven' peach fruit quality characteristics. Of primary interest was the relationship between ground color and flesh firmness. Light levels were manipulated by use of shade cloth, reflective mulch, and aluminum foil. 'Norman' trees, with a randomly chosen half of the canopy covered with 73% shade cloth, had fruit with lower levels of red color, soluble solids concentration (SSC), specific leaf weight, and average photosynthetic photon flux (PPF) than did non-shaded trees. Foil-covered 'Cresthaven' fruit were larger, less firm, and had lower SSC than non-covered fruit. Covered fruit developed yellow but not red color. Position of the fruit within the canopy of the tree also affected fruit quality characteristics. Inside fruit on both 'Norman' and 'Cresthaven' trees were smaller and firmer, had lower SSC, and were less red than fruit from the canopy exterior. The position effect was probably due to the degree of light exposure and not to the distance from the roots. Fruit on the inside of the tree canopies received much lower average PPF than outside fruit. Relationships were evaluated between ground color and firmness for both cultivars. At a given hue angle, fruit developing in high-light environments were firmer than fruit from low-light environments for 'Cresthaven', but the opposite was true for 'Norman'. Therefore, canopy position or the light environment in the vicinity of the developing fruit does not consistently influence the relationship between hue angle on the non-blush side of the fruit, and flesh firmness.<br>Master of Science

Poor colour of orange fruit causes serious economic losses to growers. Spray application of abscisic acid, prohexadione-Ca, paclobutrazol or methyl jasmonate at 6 or 3 weeks before harvest promoted fruit colour in M7 Navel. Hot water (50 °C) 5 min dip alone or combined with thiabendazol, methyl jasmonate 1 min dip (0.1 - 0.50 mM) or nitric oxide (5 - 20 µL L-1) fumigation reduced chilling injury in Midknight Valencia and Lane Late oranges.

Growth, productivity and fruit quality of grapevines are closely linked to soil water availability. Withholding of water for any length of time results in slowed growth. If drought continues yield may be lost. Vines can be manipulated to stimulate early defence mechanisms by decreasing soil water availability. By using an irrigation technique, which allows for separate zones with different soil moisture status, it is possible to stimulate response mechanisms of the root system which are normally related to water stress. The difficulty of separating 'wet' and 'dry' zones was initially overcome by using split-root plants with root systems divided between two containers. Such experiments on split-root model plants resulted in the development of an irrigation technique termed partial rootzone drying (PRD). Results from irrigation experiments using PRD have shown that changes in stomatal conductance and shoot growth are some of the major components affected (Dry et al., 1996). The idea of using irrigation as a tool to manipulate stress responses in this way had its origin in the concept that root- derived abscisic acid (ABA) was important in determining stomatal conductance (Loveys, 1984). Later experiments on split-root plants have demonstrated that many effects of water stress can be explained in terms of transport of chemical signals from roots to shoots without changes in plant water status (Gowing et al., 1990). The necessary chemical signals are provided by the dry roots, and the wet roots prevent the development of deleterious water deficits. The general hypothesis tested during this study was that partial drying of the root system gives rise to a change in the supply of root-derived chemical signals which determine changes in grapevine physiology, thereby affecting fruit quality. Experiments were conducted on split-root vines (Vitis vinifera L. cvs. Cabernet Sauvignon and Chardonnay) grown in pots of different sizes, on field-grown vines which had either their root system divided by a plastic membrane (Vitis vinifera L. cv. Cabernet Sauvignon on own roots or grafted on Ramsey rootstocks) or conventional vines with a non-divided root system (Vitis vinifera L. cv. Cabernet Sauvignon, Shiraz and Riesling) with a commercial PRD irrigation design. The irrigation treatments were vines receiving water on both sides (control) and PRD-treated vines, which only received water on one side at any time. The frequency of alternation of 'wet' and 'dry' sides was determined according to soil moisture and other influences such as rainfall and temperature. In most of the experiments the irrigation was alternated from one side to the other every 10 to 15 days. Chemical signals from roots: the role of ABA and cytokinins Studies on chemical signals have concentrated on ABA and cytokinins (CK). An improved stable isotope dilution protocol, which enables analysis of ABA and CK from the same tissue sample, was developed. Analysis of cytokinins focused on zeatin (Z), zeatin riboside (ZR), zeatin glucoside (ZG) and iso pentenyl adenine (iP). Roots are relatively inaccessible, particularly in field situations. To enable easier access to roots of field-grown vines, split-root vines were planted in a trench which was refilled with a sandy soil. This created a homogenous soil substrate and did not restrict root growth while still allowing access to roots under field conditions. Analyses of root samples of field-grown vines have shown that cytokinins and ABA may originate in roots and their concentrations can be substantially altered during an irrigation cycle. Alternating soil water conditions showed that [ABA] in roots on the 'dry' side was significantly higher compared with the 'wet' side. Due to a reduction in CK on the 'dry' side of PRD-treated vines, the ratio between ABA and CK was substantially changed during an irrigation cycle. The ABA levels in root tissue and in petiole xylem sap were negatively related to stomatal conductance. This further suggests that ABA, mostly synthesized on the 'dry' side of the root system, might be responsible for a decline in stomatal conductance. Furthermore, a higher pH of petiole xylem sap was observed in PRD-treated vines which may also contribute to the regulation of stomatal conductance. Studies on stomatal patchiness showed that non-uniform stomatal aperture occurred in field-grown vines under natural environmental conditions and was more abundant under PRD conditions. The degree of stomatal opening, determined by using a water infiltration technique, correlated with measurement of stomatal conductance. Exogenous application of a synthetic cytokinin (benzyl adenine) can override the possible ABA-mediated stomatal closure resulting from PRD treatment, providing further evidence for the in vivo role of these growth regulators in the control of stomatal conductance. The effect of benzyl adenine was transient, however, requiring repeated applications to sustain the reversal. In addition, CKs may also be important in influencing grapevine growth. Following several weeks of repeated spray applications with benzyl adenine, it was found that the development of lateral shoots in PRD-treated vines was enhanced compared to PRD-treated vines sprayed with water only. This supports the idea that the reduction in lateral shoot development seen in PRD-treated vines is due to a reduced production of CKs (Dry et al., 2000a). By measuring shoot growth rate it was found that one common feature of PRD-treated vines, which were not sprayed with CK, was a reduction of lateral shoot growth. It can therefore be speculated that the reduction in lateral growth is related to a reduced delivery of cytokinins from the roots. Zeatin and zeatin riboside concentration in shoot tips and prompt buds/young lateral shoots were reduced by the PRD treatment providing further evidence in support of this hypothesis. Water movement from 'wet' to 'dry' roots Roots, being a primary sensor of soil drying, play an important role in long- and short-term responses to PRD. Using stable isotopes of water and heat-pulse sap flow sensors water movement was traced from wet to dry roots in response to PRD. The redistribution of water from roots grown in a soil of high water potential to roots growing in a soil of low water potential may be of significance with regard to the movement of chemical signals and the control of water balance of roots. Measurements of the relative water content (RWC) have shown a slower decline of RWC of the 'dry' roots of PRD vines relative to roots of vines which received no water, despite similar water content in soil surrounding those roots. The redistribution of water may help to sustain the response to PRD for longer periods possibly releasing chemical signals and to support the activity of fine roots in drying soil. Field vines, irrigated with PRD over several growing seasons, altered their root distribution relative to the control vines. PRD caused a greater concentration of fine roots to grow in deeper soil layers and this may contribute to a better water stress avoidance. The effect on root growth may be augmented by the water movement and by the large difference in ABA to cytokinin ratio, which are also known to alter root growth. PRD makes more efficient use of available water In experiments where both control and PRD-treated vines received the same amount of water many differences between the vines were demonstrated. Under conditions where water supply was adequate for both treatments, the stomatal conductance and growth of the PRD-treated vines was restricted as has been observed in many previous experiments. As total water input was reduced, however, the stomatal conductance of PRD-treated vines became greater than control vines, suggesting that the latter were experiencing a degree of water stress, whereas the PRD-treated vines were not. This may have been due to the greater depth of water penetration in the case of the PRD-treated vines, where water was applied to a smaller soil surface area. This distinction between PRD-treated and control vines, at very low water application rates, was also reflected in pruning weights and crop yields which were actually greater in PRD-treated vines. It was concluded that at low water application rates, the PRD-treated vines were more tolerant of water stress and made more efficient use of available water. Reduction in vigor opens the canopy. The initial aim of the research which led to the development of PRD was to achieve better control of undesirable, excessive shoot and foliage growth which, from a viticultural point of view, has many disadvantages. Grapevine shoot growth rate responds very sensitively to drying soil conditions. The irrigation strategy used in the PRD experiments maintained a reduction of both main shoot and lateral shoot growth. In response to PRD a decrease in shoot growth rate and leaf area was observed. Much of the reduction in canopy biomass was due to a reduced leaf area associated with lateral shoots, thus influencing the canopy structure. This was one major factor improving the light penetration inside the canopy. Control of vegetative vigour results in a better exposure of the bunch zone to light and, as a consequence, in improved grape quality. It is likely that changes in canopy density, as a result of PRD, is causing changes in fruit quality components. Anthocyanin pigments such as derivatives of delphinidin, cyanidin, petunidin and peonidin were more abundant in berries from PRD vines; by comparison the concentration of the major anthocyanin, malvidin, was reduced. When leaves were deliberately removed from more vigorous control vines, which improved bunch exposure, the differences in fruit composition were much reduced. This further supports the idea that a more open canopy, in response to PRD, improves fruit quality by affecting the canopy structure. Fruit quality consequently determines the quality, style and value of the finished wine. Wines from this study have been produced and data on wine quality from commercial wineries are also available. Sensory evaluations have demonstrated that high wine quality from PRD-treated vineyards can be achieved without any yield-depressing effects. This study has provided evidence to support the original hypothesis. The major findings were: a) Chemical signals, altered under PRD and mostly originating from roots, play an important role in the root to shoot communication in grapevines. b) The movement of water from 'wet' to 'dry' soil layers may help to sustain chemical signals as a response of grapevines to PRD and to support the activity of fine roots in drying soil. c) A reduction in vegetative growth, in particular of lateral shoots, was sustained using PRD and affected the canopy structure which in turn, due to a better light penetration into the canopy, improved the fruit quality. d) The reduction in irrigation water applied did not have a detrimental effect on grape yield and thus the efficiency of water use was improved. e) Application of relatively low irrigation rates showed that PRD-treated vines were more tolerant of water stress and made more efficient use of available water.<br>Thesis (Ph.D.)--Department of Horticulture, Viticulture and Oenology, 2000.

Aquest treball va estudiar la irradiació ultraviolada-visible (UV-Vis) com una alternativa per a la pasteurització de sucs. Els resultats van mostrar que la irradiació ultraviolada no produeix hidroximetilfurfural i es capaç de degradar-lo. Es va proposar un mecanisme de foto-degradació i es van usar diferents models cinètics per descriure la reacció. La foto-degradació de la vitamina C va ser insignificant usant una làmpada d’emissió múltiple. A més, el processament d’UV-Vis va ser efectiu inactivant els enzims polifenoloxidasa i peroxidasa; a major temperatura major inactivació. Mentrestant, la majoria dels paràmetres fisicoquímics van ser pràcticament inalterats i la quantitat inicial de pigments es va reduir. Per tant, el processament d’UV-Vis combinat amb lleu escalfament és una alternativa viable per a la pasteurització de sucs.<br>Este trabajo estudió la irradiación ultravioleta-visible (UV-Vis) como una alternativa para la pasteurización de zumos. Los resultados demostraron que la irradiación ultravioleta no produce hidroximetilfurfural y es capaz de degradarlo. Se propuso un mecanismo de foto-degradación y se usaron diferentes modelos cinéticos para describir la reacción. Por el contrario, la foto-degradación de la vitamina C fue insignificante usando una lámpara de emisión múltiple. Además, el procesamiento UV-Vis fue efectivo inactivando las enzimas polifenoloxidasa y peroxidasa en zumos; a mayor temperatura, mayor inactivación. Mientras tanto, la mayoría de los parámetros fisicoquímicos fueron prácticamente inalterados y la cantidad inicial de pigmentos fue reducida. Por lo tanto, el procesamiento UV-Vis combinado con un calentamiento suave representa una alternativa viable para la pasteurización de zumos.<br>This work studied the ultraviolet-visible (UV-Vis) irradiation as an alternative for fruit juice pasteurisation. The results showed that ultraviolet irradiation does not produce hydroxymethylfurfural and is capable of degrade it. A mechanism of photo-degradation was proposed and different kinetic models were used to describe the reaction. On the contrary, the photo-degradation of vitamin C was insignificant using a multi-wavelength emitting lamp. Moreover, the UV-Vis processing was effective inactivating the enzymes polyphenoloxidase and peroxidase in fruit juices. The higher the temperature the higher the inactivation. Meanwhile, most physicochemical parameters were practically unaltered and the initial quantity of pigments was reduced. Therefore, the UV-Vis processing combined with a mild-heating represents a viable alternative for fruit juice pasteurisation.