Strawberries are an extremely perishable fruit mainly due to their soft texture and sensitivity to fungal infection. The fungal pathogen Botrytis cinerea is responsible for grey mould on strawberries and is the main causal agent of postharvest decay and subsequent economic loss. As an alternative to fungicides, manipulation of plant nutrition, such as calcium and boron, has been suggested as a means of disease management. This project investigated the effects of calcium and boron application on fruit quality and grey mould development in strawberry. The effect of calcium on fruit quality, grey mould development and leaf blight in strawberry cultivars ‘Aromas’ and ‘Selva’ was investigated through preharvest and postharvest applications. To determine the effect of preharvest application, calcium sulphate in 0.25X strength Hoagland’s solution was applied at 0, 100, 300 and 500 ppm Ca through fertigation. Fully-ripened fruit were harvested and evaluated for postharvest quality at harvest and then after storage at 10⁰C, 90±5% RH for 2 to 10 days. Although fruit firmness of both cultivars declined slightly during storage, this was not affected by preharvest calcium application. Similarly, preharvest calcium treatment had no effect on the external appearance, pH, soluble solids content (SSC) or titratable acidity (TA). No grey mould development was observed on fruit at harvest when flowers were inoculated with a conidia suspension of B. cinerea (10⁴ conidia per mL). However, fruit harvested from plants that received calcium at any concentration had less incidence of grey mould during storage at 10⁰C, 90±5% RH for 14 days than fruit harvested from plants that received no calcium for both cultivars. For ‘Aromas’, 79% and 51% of fruit, and for ‘Selva’, 69% and 43% of fruit, showed rot when treated with 0 and 500 ppm Ca, respectively. The shelf life of ‘Aromas’ and ‘Selva’ increased by about 8% when plants received 500 ppm Ca in comparison with plants that received 0 ppm Ca. After 7 days of incubation at 22 to 24⁰C, there was no difference between blight lesions on wound-inoculated detached leaves from different calcium treatments for either cultivar. However, the lesions on ‘Selva’ were smaller than on ‘Aromas’. The calcium levels in leaves from plants that received calcium at any concentration were adequate for strawberry growing and significantly higher (P < 0.05) than in leaves from plants that received 0 ppm Ca. However, calcium treatment did not ensure transfer of calcium to fruit tissues. Calcium lactate and calcium chloride were used as postharvest calcium treatments at 1500, 3000 and 4500 ppm Ca. Fruit of ‘Selva’ were dipped in calcium solution for 5 min and wound-inoculated with B. cinerea (10⁶ conidia per mL). Calcium lactate and calcium chloride at 3000 and 4500 ppm Ca, respectively, were most effective in delaying Botrytis rot development on ‘Selva’ after 7 days of storage at 10⁰C, 90±5% RH. Storage for least 24 h after calcium dips prior to inoculation was required to delay the development of fruit rot. Fruit harvested early in the season seemed to be less susceptible to grey mould than those harvested later. However, calcium treatment tended to be more effective when applied to late-season fruit. Preharvest boron treatment, applied as for calcium but at 0, 0.25, 0.5 and 1.0 ppm B, had no effect on fruit firmness of either cultivar. However, firmness of ‘Aromas’ fruit was slightly greater than ‘Selva’ fruit for all treatments. The amount of boron applied had no effect on the external appearance, pH, SSC or TA for either cultivar after storage of fruit for up to 10 days. Application of boron had no effect on fruit grey mould development in either cultivar. Furthermore, boron had minimal effect on the incidence of blight on woundinoculated detached leaves of ‘Aromas’ 7 days after inoculation. However, blight lesion diameters on ‘Selva’ leaves in the 1.0 ppm B treatment (8.0 mm) were significantly smaller (P < 0.001) than in the 0 ppm B treatment (13.0 mm). Phytotoxicity was observed in boron treatments even at the level considered optimum for strawberry growing. Severity increased with increasing boron concentration but no consistent effect on flower death or flower abortion was observed. In conclusion, strawberry is sensitive to boron toxicity. Calcium may enhance fruit firmness and, consequently, delay grey mould development if calcium penetrates the fruit. Postharvest calcium treatment tended to be more effective in delaying development of grey mould when applied to late-season fruit. Calcium lactate is a potential alternative to calcium chloride for reducing decay caused by B. cinerea in strawberry without providing undesirable bitterness. This finding may provide a basis for application in industry. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1331382 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine 2008

Brown and Penicillium rot (blue and green mould) are the most common postharvest diseases in New Zealand, causing significant postharvest fruit losses. Current practice uses fungicides to control the postharvest diseases; however there are perceived health risks associated with the use of such chemicals. Recently, there has been substantial interest in chemicals that are considered Generally Regarded as Safe or GRAS and natural products as alternative postharvest treatments to replace currently used fungicides. In this study, ethanol (GRAS chemical) and the natural products honey, milk and essential oils (lemon, lemongrass, manuka and orange) were assessed as potential alternative treatments to replace the currently used fungicides on both peaches and oranges. In pilot studies ethanol was applied to the fruit by either vapour or dipping (30 seconds or 1.5 minutes). Honey, milk and essential oils were applied by dipping at 30 seconds. Essential oils were also tested using a microtiter assay. Exposing fruit to ethanol vapour proved effective at inhibiting fungal growth, but impacted negatively on fruit quality. Peaches that were exposed to 70% to 100% ethanol vapour were protected against fungal infection for up to 30 days when stored at either 4ºC or room temperature. This is compared to two days for untreated peaches and three days for fungicide -treated peaches. However, the ethanol-treated peaches suffered from severe browning. In contrast, 20% ethanol protected peaches for ten days when stored at 4ºC and two days at room temperature. The fruit that were exposed to 20% ethanol did not brown as a result of the treatment. Oranges that were exposed to 20%, 50%, 70% and 100% ethanol vapour were protected from fungal inhibition for 30 days at both 4ºC and room temperature, but they too suffered from severe browning. Dipping was not as effective as vapour at protecting against fungal infection, but had a little effect on fruit quality. Peaches dipped in 20% to 100% ethanol were completely rotten by ten days when stored at room temperature, but the peaches experienced little to no browning. Untreated and fungicide-treated fruit were protected for one day and two days, respectively. Milk and honey do not appear to have potential as postharvest treatments. Peaches that were treated with 20%, 50% and 100% whole milk and 50% manuka honey showed greater degree of fungal infection compared to untreated peaches after both room temperature and 4ºC storage. At room temperature, peaches that were exposed to 20%, 50% and 100% milk were completely rotten at eight days, compared with ten days for untreated peaches. In contrast, at 4ºC, peaches that were treated with 100% milk were completely rotten at 30 days, while only a slight fungal infection observed on untreated fruit. Similar to milk, honey-treated peaches were also completely rotten at 30 days at 4ºC storage.In vitro (microtiter) assay of the essential oils showed that orange and manuka oils appeared to be effective only at high concentrations. In contrast, lemongrass and lemon oils appeared to be effective even at low concentrations. Of the essential oils tested in the in vivo assay, lemongrass and lemon oils have the greatest potential. Oranges that were exposed to 0.05% lemongrass oil, 0.25% and 0.5% lemon oil were protected for 30 days when stored at 4ºC or room temperature. They provided the best antifungal activity compared to the other concentrations of all four essential oils tested as well as fungicide treatment for 30 days. Of all the treatment tested, 0.05% lemongrass oil, 0.25% and 0.5% lemon oil appeared to be the most promising treatments. However, these treatments need to be tested for antifungal effects, fruit quality, flavour and nutritional effects in large scale experiments before they can be applied as replacements to currently used fungicides. Also, essential oils are complex compounds; therefore it would be of interest to determine the active compound(s) of the lemongrass and lemon oils.

Thesis (MSc Food Sc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The South African avocado fruit industry is export driven and the successful storage of fruits for extended periods is, therefore, essential. It was recorded that 7.7 million cartons were exported during the 1995 season. The shipping of the avocados takes approximately 15 days and the fruits are being stored at low temperatures to minimise the possibility of fruits softening. Unfortunately low temperature storage results in chilling injury. A possible method to increase avocado resistance to chilling injury is to administer a heat shock treatment. In this way the fruits are protected from chilling injury by inducing the formation of so-called heat-shock proteins which render the cell membranes more resistant to chilling injury. The objective of this study was to evaluate different heat shock treatment protocols as a method of preventing or minimising chilling injury and to extend the shelf-life of avocado fruits while exporting at the lowest possible temperature. Examining the effect of different temperatures and exposure times on the quality of the different avocado cultivars pursued this. The exterior chilling injury on each fruit was quantified and the firmness and internal quality parameters evaluated. A total of 32 Experimental Studies were conducted. The results showed that the Hot Water Heat shock Treatment (HWHST) worked effectively for the South African 'Fuerte' cultivar between 40° and 42°C for exposure times of between 20 and 30 min. The 'Edranol' cultivar also showed promising results between 40° and 42°C for exposure time of between 8 and 22 min. The HWHST was not effective on the South African 'Hass' cultivar. The 'Ryan' cultivar with its thick skin made this cultivar less susceptible to chilling injury and therefore HWHST would be unnecessary. The 'Pinkerton' cultivar had a lot of factors that influenced the results. Therefore, more research needed to be done on the 'Pinkerton' cultivar, before any conclusions could be obtained from this cultivar, although it showed potential. Hot air treatment worked fairly well, but unfortunately the long exposure time needed made this treatment unpractical. Throughout the whole study the importance of maturity surfaced as a major role in all the aspects of post harvest quality. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse avokado vrugtebedryf is hoofsaaklik gerig op die uitvoermark en daarom is dit belangrik dat die vrugte vir 'n bepaalde tyd suksesvolopgeberg kan word. Die sensus opname gedurende die 1995 seisoen het getoon dat 7.7 miljoen bokse avokados uitgevoer is. Die avokados word vir ongeveer 15 dae per boot vervoer, wat kan lei tot vrugte wat sag word. Om dit te verhoed, word die vrugte by lae temperature opgeberg. Ongelukkig veroorsaak lae opbergingstemperature koueskade. 'n Moontlike metode om avokados te beskerm teen lae temperature en koueskade te verminder, is om 'n hitteskok behandeling toe te pas. Op hierdie manier word die vrugte beskerm teen koueskade deur die vorming van sogenaamde hitteskok proteïene wat die selwande meer bestand maak teen koueskade. Die doel van hierdie studie was om die verskillende hitteskok behandelings protokols te evalueer as 'n metode van beskerming of vermindering van koueskade en om sodoende die rakleeftyd van avocados te verleng as die vrugte by lae temperature uitgevoer word. Eksperimente is uitgevoer om die effek van verskillende temperature en blootstellingstye op die kwaliteit van die verskillende avokado kultivars te bepaal. Die koueskade op die oppervlakte van elke vrug is bepaal en die fermheid en interne kwaliteit parameters is geëvalueer. In totaal is daar altesaam 32 Eksperimentele Studies gedoen. Die resultate het gewys dat die Warm Water Hitteskok Behandeling (WWHB) effektief was op die Suid-Afrikaanse 'Fuerte' kultivar by temperature tussen 40° en 42°C en by blootstellingstye van tussen 20 en 30 min. Belowende resultate is ook met die 'Edranol' kultivar by temperature tussen 40° en 42°C met blootstellingtye van tussen 8 en 22 min behaal. Die WWHB was oneffektief vir die Suid-Afrikaanse 'Hass' kultivar. Die 'Ryan' kultivar se dik skil het hierdie kultivar minder vatbaar gemaak vir koueskade en daarom was 'n WWHB onnodig gewees. By die 'Pinkerton' kultivar kon daar nog nie 'n gevolgtrekking gemaak word nie, aangesien daar nog baie faktore is wat ondersoek moet word, alhoewel die kultivar baie potentiaal getoon het. Warm lug behandeling het potensiaal gehad, maar die lang blootstellingstye het hierdie behandeling onprakties gemaak. Gedurende die hele studie is daar klem gelê op die rypheisgraad van die vrugte wat na vore gekom het as 'n belangrike faktor wat 'n hoofrol speel in al die aspekte van die na-oes kwaliteit.

Thesis (MScFoodSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Postharvest losses of three different vegetables (tomato - a fruit, cabbage - a leaf and carrot - a root vegetable) were investigated directly after retail purchasing and during consumer simulated storage. To conduct this study, three retail outlets (2 supermarkets and an outdoor market) were selected in Stellenbosch, South Africa. Retail prices of each vegetable were recorded from each respective Outlet. Surrounding environmental conditions (air temperature and relative humidity) at retail and during simulated consumer storage were also monitored. Vegetable postharvest losses were determined by quantifying the incidence of physical loss and changes in physico-chemical properties (colour, firmness, weight loss, ascorbic acid, total pigments, total soluble solids, titratable acid and proximate composition) over time. The percentage losses observed were then used to estimate the associated economic and environmental resource impacts of postharvest vegetable losses at the national level. Vegetable losses immediately at retail purchase were 14.56%, 21.21% and 17.93% for tomato, cabbage and carrot, respectively. The estimated combined volume lost for all three vegetables at national level was approximately 26 460 t valued at R33.70 million. Overall economic loss was highest for tomatoes and least for carrots. The magnitude of the losses observed differed for all the outlets. Vegetable losses were mostly high for the produce from the outdoor market compared to the supermarkets during storage. Throughout the whole trial, mechanical damage accounted for at least 50 to 70% of the losses while the remainder was due to decay and insect damage. Post retail storage temperature; ambient (22–25ºC) vs. cold store (0ºC and 10–12 ºC) had a significant (P<0.05) effect on the vegetable losses. This was for both quantitative and qualitative attributes. Losses for tomato and cabbage were 18.52% and 16.67% after 3 days while carrot losses were 11.83% at 7 days after having been kept in the recommended respective cold storage temperatures. Ambient storage losses were also lowest for carrots at 22.53% after 7 days, while tomato and cabbage losses stood at 24.27% and 34.34% after 3 days of storage, respectively. Vegetable firmness generally decreased while weight loss increased with storage time. Colour development increased favourably at ambient temperature for the tomato whereas for cabbage and carrot better colour retention was observed in the cold storage. Chemical changes for all three vegetables were also most pronounced at ambient temperature with significant (P<0.05) losses observed for ascorbic acid. Changes were also noted for total pigments, soluble solids and acidity, however there was no common significant trend for all three vegetables. Estimates of carbon dioxide emissions reveal that postharvest vegetable losses contribute to unwarranted emissions of at least 1.37 – 13.77 million tonnes of carbon dioxide equivalents (CO2eq.) at the national level. The losses are also accompanied by wastage of approximately 3.74 – 4.35 million m3 of fresh water as well as 14.79 – 111.63 million MJ of fossil energy. The vegetable with highest production volumes and retail price was the tomato and accordingly, its postharvest losses had the severest environmental and resource impacts. / AFRIKAANSE OPSOMMING: Die ná-oes-verliese van drie verskillende groentes (tamatie – 'n vrug, kool – 'n blaar, en wortel – 'n wortelgroente) is direk ná kleinhandelaankope en tydens gesimuleerde verbruikersberging ondersoek. Ten einde hierdie studie uit te voer, is drie kleinhandelsafsetpunte (twee supermarkte en 'n opelugmark) in Stellenbosch, Suid-Afrika gekies. Die kleinhandelpryse van elke groente van die drie onderskeie afsetpunte is opgeteken. Omliggende omgewingstoestande (lugtemperatuur en relatiewe humiditeit) tydens verkope en gesimuleerde verbruikersberging is ook gemonitor. Die ná-oes-verliese van die groentes is bepaal deur die voorkoms van fisiese verlies en veranderings in fisio-chemiese eienskappe (kleur, fermheid, gewigsverlies, askorbiensuur, totale pigmente, totale oplosbare suikers, titreerbare suur en algemene samestelling) met verloop van tyd te versyfer. Die waargenome persentasie verliese is gebruik om die geassosieerde ekonomiese en omgewingshulpbron-impak van ná-oes-groenteverliese op nasionale vlak te beraam. Groenteverliese met kleinhandelaankope was onderskeidelik 14.56%, 21.21% en 17.93% vir tamaties, kool en wortels. Die beraamde saamgestelde volume verlies vir al drie groentes op nasionale vlak was ongeveer 26 460 t, met 'n waarde van R33.70 miljoen. Die algehele ekonomiese verlies was die hoogste vir tamaties en die laagste vir wortels. Die omvang van die waargenome verliese het vir al die afsetpunte verskil. Groenteverliese tydens berging was hoofsaaklik hoog vir die produkte van die opelugmark in vergelyking met dié van die supermark. Tydens die algehele proefneming was meganiese skade verantwoordelik vir ten minste 50 tot 70% van die verliese, terwyl die res aan verrotting en insekskade toegeskryf kan word. Bergingstemperatuur ná kleinhandelaankope: omgewingstemperatuur (22 – 25 ºC) vs. koue berging (0 ºC en 10–12 ºC) het 'n beduidende (P < 0.05) uitwerking op groenteverlies gehad. Dit geld vir sowel kwantitatiewe as kwalitatiewe attribute. Verliese vir tamaties en kool was onderskeidelik 18.52% en 16.67% ná drie dae, terwyl dit vir wortels 11.83% teen sewe dae was nadat dit teen die aanbevole onderskeie koue bergingstemperature geberg is. Bergingsverliese in omgewingstemperatuur was ook die laagste vir wortels teen 22.53% ná sewe dae, terwyl die verlies van tamaties en kool onderskeidelik 24.27% en 34.34% was ná drie dae se berging. Die fermheid van die groente het oor die algemeen met die duur van berging verminder, terwyl gewigsverlies toegeneem het. Kleurontwikkeling het gunstig teen omgewingstemperatuur toegeneem vir die tamaties, terwyl die kleur van kool en wortels beter in die koue berging behou is. Chemiese veranderinge vir al drie groente was die sterkste teen omgewingstemperatuur, met beduidende (P < 0.05) verliese van askorbiensuur wat waargeneem is. Veranderinge is ook gemerk rakende totale pigmente, oplosbare vaste stowwe en suurgehalte. Daar was egter geen algemene beduidende neiging vir al drie groentes nie. Beramings van koolstofvrystellings toon dat ná-oes-groenteverlies tot ongeoorloofde vrystelling van ten minste 1.37 tot 13.77 miljoen ton koolstofekwivalente (CO2eq.) op nasionale vlak bydra. Die verliese gaan ook gepaard met verbruik van ongeveer 3.74 tot 4.35 miljoen m3 vars water asook 14.79 tot 111.63 miljoen MJ fossielbrandstof. Die groente met die hoogste produksievolume en kleinhandelprys was die tamaties, en gevolglik het tamaties se ná-oes-verliese die ernstigste impak op die omgewing en op hulpbronne.

Thesis (MScAgric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: By world standards South Africa’s contribution to fresh blueberry production is very small, a mere 0.25 %. This seemingly insignificant and unimpressive statistic is, however, by no means indicative of the impending impressive potential the South African blueberry industry holds. South Africa is encountering a rapid growth phase off a very small base and the current 100-150 ton export crop is expected to increase to a range of 500 to 600 tons or more in the next five years. Consequently, export by sea must be considered as a logistic alternative. Seafreight success relies on controlled atmosphere storage which in turn relies on berries of exceptional quality. To achieve this, fundamental differences between blueberry cultivars must be examined and blueberry handling and storage regimes must be assessed and optimised. This study investigates the storage potential of certain rabbiteye blueberries relative to controlled atmospheres and short pre-cooling delays. Quality assessments were based on external colour, soluble solids, titratible acidity, firmness and decay development. Furthermore, the respiration and ethylene production rates as well as moisture loss, of various cultivars were determined to characterize fundamental differences amongst cultivars and to gain insight into their postharvest behaviour. Lastly the effect of infection on pigment levels of blueberry flesh and peel was examined for the purpose of laboratory experience. Controlled atmosphere storage had the greatest impact on berry firmness and percentage decay. No off flavours were detected during sensory analysis at the CA levels tested. CAstored berries were firmer and incidence of decay was reduced significantly. Significant decay reduction was challenged by the market tolerance of no more than 2 %. Decay suppression and storage extension was insufficient (for the set period), particularly after the shelf life period. Cultivar and seasonal differences as well as picking maturity and inoculum pressure determine blueberry CA storability. CA may be a valuable technology, however advances must first be made in ensuring optimal blueberry quality to warrant export by sea. Short pre-cooling delays (0, 2, 4, 6 h) at 20 ºC had no effect on colour (L, C, H), total soluble solids, titratable acidity and firmness of blueberry cultivars, ‘Centurion’, ‘Premier’ and ‘Tifblue’. Results for percentage decay indicate that prompt cooling becomes more critical as the duration of storage increases, particularly when market specification of no more than 2 % decay must be met. Berries subjected to longer delays appear to be more susceptible to decay. Differences exist among cultivars and knowledge gained from this research can be used to adapt handling and cooling regimes. Information generated will benefit cultivar selection for marketing (local vs. export), storage (short vs. long term) and logistics (air vs. seafreight). Rabbiteye blueberry cultivars differ considerably in terms of their respiration rate, ethylene production and moisture loss. These quality parameters were evaluated for various cultivars at 15 ºC. ‘Climax’ appears to have the highest respiration rate, ethylene production and moisture loss, whilst ‘Premier’ has the lowest respiration rate and ethylene production was too low to be detected by gas chromatography. The lowest moisture loss proportionality constant was found for ‘Tifblue’ and ‘Centurion’. A change in blueberry flesh colour from white to dark red was noted in infected berries. Artificial inoculation with Botrytis cinerea showed a similar result. The colour change was evaluated by comparing anthocyanin pigment levels (determined by spectrophotometry and HPLC) of the peel and flesh. Anthocyanin content of infected flesh doubled, whilst that of infected peel was less than 50 % of the control. Pigment leakage has been reported in blueberries. It would appear that cell disruption, induced by infection may facilitate migration of anthocyanin from the peel to the flesh. The storage potential of blueberries depends on cultivar, maturity at harvest, climatic conditions as well as the inoculum pressure. Under favourable conditions storage life of blueberries can be manipulated effectively. Further cultivar specific research that targets relevant quality issues should be investigated. Reliable techniques should be developed to quantify blueberry firmness changes. Research on inoculum levels may give insight into the reduction of decay pressure and decay suppressing alternatives such as antibacterial pads can be examined. Peel integrity relative to decay susceptibility can also be researched on a cellular level. / AFRIKAANSE OPSOMMING: Suid-Afrika se bydrae tot wêreld bloubessie produksie is baie klein, ‘n skrale 0.25 %. Hierdie onindrukwekkende statistiek weerspieel egter glad nie die indrukwekkende potensiaal van die Suid-Afrikaanse bloubessie bedryf nie. Die bedryf ondervind tans ‘n dramatiese groei met ‘n klein begin vanaf die huidige 100-150 ton opbrengs tot wat volgens verwagting binne die volgende vyf jaar sal styg tot in die orde van 500-600 ton. Na aanleiding van die verwagte toename in produksie, sal seevrag verskeping oorweeg moet word as alternatief vir uitvoer eerder as lugvrag. Die sukses van seevrag lê in die gebruik van beheerde atmosfeer opberging (BA), waarvan die sukses op sy beurt bepaal word deur bessies van hoogstaande kwaliteit. Om steeds aan die verwagtings van die oorsese mark te voldoen moet grondliggende verskille tussen bloubessie kultivars ondersoek word en daaropvolgend moet hantering en opbergingstelsels aangepas en geoptimeer word. Die navorsing bestudeer die opbergingspotensiaal van verskeie rabbiteye bloubessies relatief tot beheerde atmosfere en kort vertragings in verkoeling. Kwaliteit, gebasseer op eksterne kleur, oplosbare deeltjies, titreerbare sure, fermheid en persentasie bederf, is ondersoek. Die respirasie en etileenproduksie tempos sowel as vogverlies van verskeie kultivars was verder bepaal om die fundamentele verskille tussen kultivars te bepaal, sowel as insig te verwerf in na-oes gedrag. Die effek van infeksie op pigment vlakke van bloubessie vlees en skil was ondersoek vir die doel van laboratorium ondervinding. Beheerde atmosfeer opberging het die grootste effek getoon op bessie fermheid en persentasie bederf. Na aanleiding van sensoriese toetse is daar geen wansmaake aangeteken ten op sigte van die BA vlakke wat getoets is nie. Bessies onderworpe aan beheerde atmosfeeriese toestande was fermer en bederfonderdrukking was beduidend. Die markverdraagsaamheid ten opsigte van bessiebederf, is egter 2 %. Hiervolgens was onderdrukking van verval asook opbergingsvermoë, onvoldoende (spesifiek na die rakleeftyd). Kultivar en seisoenale verskille asook plukrypheid en inokulum druk, bepaal ook die sukses van BA opberging. BA word beskou as ‘n waardevolle tegnologie vir verlenging van opberging. Dit blyk egter dat daar eers ‘n vooruitgang gemaak moet word in die versekering van optimale bessie kwaliteit voordat verskeping oorweeg kan word. Kort vertragings (0, 2, 4, 6 uur by 20 ºC) in verkoeling, het geen invloed gehad op kleur, (L, C, H), totale oplosbare vastestowwe, titreerbare suur en fermheid van bloubessie kultivars ‘Centurion’, ‘Premier’ en ‘Tifblue’ nie. Bederfresultate dui daarop dat onmiddelike verkoeling krities is, veral by verlengde opberging, om aan die 2 % bederf drempelwaarde te voldoen. Bessies onderhewig aan langer vertragings voor verkoeling, blyk meer vatbaar te wees vir bederf. Verskille bestaan tussen kultivars en kennis ingewin tydens hierdie navorsing kan toegepas word om hanteringsprosedures en verkoeling aan te pas. Ingeligte besluitneming kan dus ten opsigte van kultivarspesifieke bemarking (plaaslik en uitvoer), opberging (kort- en langtermyn) en vervoer (lug- en seevrag) gemaak word. Rabbiteye bloubessie kultivars verskil aansienlik ten opsigte van hul respirasietempo, etileenproduksie en vogverlies. Laasgenoemde kwaliteitsbepalers is by verskillende kultivars ondersoek by 15 ºC. ‘Climax’ het die hoogste respirasietempo, etileenproduksie en vogverlies getoon, terwyl ‘Premier’ die laagste respirasietempo gehad het, en die etileenproduksie te laag was om met die gaschromatograaf te bepaal. Die laagste vogverlies proporsionaliteitskonstante is waargeneem tussen ‘Tifblue’ en ‘Centurion’. ‘n Verandering is waargeneem in bloubessie vrugvleeskleur van wit tot donkerrooi by besmette bessies. ‘n Soortgelyke resultaat is verkry met kunsmatige inokulering met Botrytis cinerea. Die kleurverskil is geëvalueer deur vergelyking te tref met die antosianienpigment vlakke tussen die skil en die vlees (bepaal deur spektrofotometrie en HPLC). Antosianieninhoud van besmette vrugvlees het verdubbel, terwyl die van besmette vrugskil minder as 50 % van die kontrole groep was. Pigmentlekkasie is al vermeld by bloubessies. Dit wil voorkom of selskade veroorsaak deur infeksie beweging van antosianien vanaf die skil na die vlees kan aanhelp. Die opbergingspotensiaal van bloubessies hang af van kultivar, rypheid by oes, omgewings toestande sowel as inokulum druk. Onder gunstige toestande kan bloubessies se opbergingsvermoë effektief gemanipuleer word. Verder kultivar-spesifieke navorsing wat relevante kwaliteits kwessies aanspreek, kan gedoen word. Verder kan betroubare tegnieke in die meting van bloubessie fermheid veranderinge ondersoek word. Navorsing ten opsigte van inokulum vlakke mag insig gee in terme van bederf-druk vermindering en die gebruik van bederf-onderdrukking alternatiewe soos anti-bakteriese lappies. Skil integriteit relatief tot bederf-vatbaarheid kan ook op sellulere vlak ondersoek word.

Thesis (MSc)--Stellenbosch University, 2002. / 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. / 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.

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

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Production of the South African ‘Triumph’ persimmon grown as a counter season supply to European markets declined from 740 ha in 2008 to 550 ha in 2011 due to, among other factors, quality variation observed when the fruit arrives at the market. Variation in fruit quality affects acceptability, hence profitability. The aim of this study was to investigate the effects of time of maturity (influenced by region and paclobutrazol treatment), stage of maturity at harvest (colour), orchard differences and wind on ‘Triumph’ persimmon storage potential (6.5 weeks at -0.5 oC and after 4 days shelf-life at 20 oC) as well as evaluation of near-infrared spectroscopy (NIRs) as an objective tool to sort fruit of various maturity stages. The first study compared storage potential of fruit from an early region treated with paclobutrazol, an untreated early region and a late region harvested at 4 stages of maturity determined by the Perishable Product and Inspection Services (PPIS) persimmon colour chart. Harvesting South African ‘Triumph’ persimmon at colour group 3 (PPIS colour chart values 5-6 compared to commercial harvest at 4-5) demonstrated the potential to improve fruit storage potential regardless of the maturity time. The second trial compared storage potential of fruit harvested at colour group 3 from 4 orchards on each maturity time in the 2012 season and 5 orchards on adjacent farms in the 2013 season. The results demonstrated that, although harvesting fruit at PPIS colour chart values 5-6 improved the general post-harvest quality, significant quality variation resulting from orchard factors could occur. The third trial investigated the effect of wind on storage potential of ‘Triumph’ persimmon fruit by simulating wind and wind damage by blowing trees for 10 min, shaking trees for 2 min, defoliating half of the trees and twisting fruit stalks. Wind simulations increased soft fruit after cold storage, decreased titratable acidity (TA) and total soluble solids (TSS) after shelf-life and delayed fruit colour development after storage and after shelf-life. The effect of wind simulation and simulated damage on storage potential varied per season and should be studied further in more detail. However, orchard practices that reduce wind power may improve quality of stored ‘Triumph’ persimmon fruit. The fourth trial investigated the possibility of using near infra-red spectroscopy (NIRs) as an alternative or complimentary non-destructive fruit sorting tool. Near infra-red (NIR) spectra were obtained over the wavelength range of 800-2500 nm. Flesh firmness, Sinclair (IQ) firmness, TSS, TA and fruit colour were determined using conventional methods after spectral measurements. All measured quality parameters showed that PPIS colour chart alone may not categorise fruits into precise distinctive maturity stages. NIR calibration and validation models proved that NIRs predicts TSS and fruit colour throughout post-harvest storage of ‘Triumph’ persimmon fruit. In conclusion, this study found that harvesting South African ‘Triumph’ persimmon at PPIS colour chart values 5-6, orchard management for post-harvest quality, reducing wind damage and using NIRs as complimentary maturity indexing tool may improve storage potential of the South African ‘Triumph’ persimmon fruit. / AFRIKKANSE OPSOMMING: Die produksie van Suid-Afrikaanse ‘Triumph’ persimmons om die Europese markte te voorsien gedurende die tyd van die jaar wanneer daar geen vrugte op die mark is nie, het afgeneem vanaf 740 ha in 2008 tot 550 ha in 2011. Een van die faktore wat ‘n rol gespeel het in die afname van produksie is die variërende kwaliteit van vrugte op die mark. Vrugkwaliteit variasie affekteer die bemarkbaarheid van vrugte, en dus winsgewendheid. Die doel van die studie was om die effek van tyd van oesrypheid (soos bepaal deur kleur en beïnvloed deur produksie area en paclobutrazol behandeling), boordvariasie en wind op ‘Triumph’ persimmon opberging (6 weke en 3 dae by -0.5 oC) en rakleeftyd (4 dae by 20 oC) te bepaal. Die studie het ook die geskiktheid van naby-infrarooi spektroskopie (NIRs) as ‘n objektiewe sorteringsinstrument van verskeie rypheidsstadia getoets. Die eerste proef vergelyk opbergingspotensiaal van vrugte uit ‘n vroeë produksie area behandel met paclobutrazol, onbehandelde vrugte uit ‘n vroeë produksie area, en vrugte uit ‘n laat produksie area geoes by 4 verskillende stadia van rypwording soos bepaal deur die Bederfbare Produkte en Inspeksie Dienste (Perishable Product and Inspection Services (PPIS)) se persimmonkleurkaart. Die oes van Suid-Afrikaanse persimmons by kleurkaartgroep 3 (PPIS kleurkaart waardes 5-6 in vergelyking met kommersiële oes by 4-5) het die potensiaal om vrugopbergbaarheid te verbeter onafhanklik van produksie area. Die tweede proef vergelyk opbergbaarheid van vrugte van 4 boorde in elke rypwordings tyd / area (2012 seisoen) en 5 boorde op aangrensende plase (2013 seisoen) wat by kleurgroep 3 geoes is. Die resultate demonstreer dat alhoewel vrugkwaliteit na-oes beter behou word wanneer vrugte by PPIS kleurkaartwaardes van 5-6 ge-oes word, betekenisvolle kwaliteitsvariasie bestaan as gevolg van boordverskille. Die derde proef ondersoek die effek van gesimuleerde wind en windskade op die opbergbaarheid van ‘Triumph’ persimmonvrugte. Dit is gedoen deur bome vir 10 min te blaas met lug met behulp van ‘n kommersiële boordspuitpomp, hard te skud vir 2 min, deur die helfte van die blare te stroop, en deur die vrugstele te wring. Windsimulering verhoog die persentasie sagte vrugte na koueopberging, verminder titreerbare sure (TS) en totale oplosbare vastestowwe (TOVS) na rakleeftyd en vertraag vrugkleurontwikkeling na opberging en rakleeftyd. Die effek van windsimulering en geassosieerde skade op opbergbaarheid het baie gevarieer tussen seisoene en moet verder en in meer detail bestudeer word. Boordpraktyke wat windkrag verminder mag egter ‘n verbetering in die kwaliteit van ‘Triumph’ persimmonvrugte tot gevolg hê. Die vierde proef bestudeer die geskiktheid van NIRs as ‘n alternatiewe of aanvullende niedestruktiewe vrugsorteringsapparaat. NIR spektra is ingesamel tussen 800-2500 nm. Fermheid, Sinclair (IQ) fermheid, TOVS, TA en vrugkleur is bepaal deur konvensionele metodes na spektrale metings. Alle vrugkwaliteitsparameters het gewys dat die PPIS kleurkaart nie alleen die vrugte in presiese rypheidsklasse kan indeel nie. NIR kalibrasie en validasie modelle bewys dat NIRs TOVS en vrugkleur ‘Triumph’ persimmon na-oes kwaliteit kan voorspel. In gevolgtrekking het die studie bevind dat die oes van Suid-Afrikaanse persimmonvrugte by PPIS kleurkaartwaardes van 5-6, boordbestuurspraktyke vir die behoud van na-oes kwaliteit, windskade vermindering en die gebruik van NIRs as ‘n aanvullende rypheidsindekseringsapparaat die opbergingsvermoë van Suid Afrikaanse ‘Triumph’ persimmons mag verbeter.

Made available in DSpace on 2014-06-11T19:35:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-10Bitstream added on 2014-06-13T19:25:21Z : No. of bitstreams: 1 mattos_lpv_dr_botfca.pdf: 1675965 bytes, checksum: 3faf029e6aef13589d4485a2b0a651ee (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Penicillium digitatum, agente causador do bolor verde, e Guignardia citricarpa, agente causador da mancha preta, depreciam os frutos citricos. O controle desses patógenos em frutos é realizado com fungicidas sintéticos. Devido a preocupação da sociedade com os riscos de contaminação ambiental, intoxicação humana principalmente infantil e animal e ao surgimento de isolados fúngicos resistentes aos fungicidas sintéticos, estão em desenvolvimento técnicas alternativas aos fungicidas para uma agricultura mais sustentável. O objetivo do trabalho foi avaliar os efeitos de óleos essenciais e fixos e dos agentes de biocontrole no controle de P. digitatum e G. citricarpa em frutos laranja Pêra em pós- colheita. Assim, foram testados os óleos fixos de Allium sativum, Copaifera langsdorffii, Azadirachta indica; e os óleos essenciais de Pogostemon cablin, Mentha arvensis, Eucalyptus spp., Cymbopogon citratus, Ocimum basilicum var. Maria bonita, Romarinus officinalis, Lippia sidoides, Zingiber officinale, Citrus aurantifolia, Piper aduncum e Ocimum basilicum. Além dos óleos, também foram estudados os seguintes agentes de biocontrole: Bacillus subtilis (Serenade®), Bacillus subtilis e Bacillus lichiniformes (Nemix®), Pichia guilliermondii (L29), Sporobolomyces roseus (L41), Rhodotorula mucilagenosa (L17), Sporodiobolus pararoseus, Pichia sp. (L4-1), Debaryomyces hansenii (L62), Pichia membranifaciens (L21) e uma bactéria isolada da laranja. Tanto os agentes de biocontrole, quanto os óleos foram testados in vivo e in vitro contra os dois patógenos. Para a avaliação da atividade dos óleos essenciais e dos antagonistas in vivo, no controle de P. digitatum, foram utilizadas laranjas Pêra. Cada fruto foi ferido em dois pontos opostos, na região equatorial, atingindo a região do albedo. Após o ferimento, os frutos foram inoculados com 20 μL da suspensão de conídios... / Penicillium digitatum, causal agent of green mold, and Guignardia citricarpa causal agent of black spot. Detracts the citrus fruit, the control of these pathogens is made with synthetic fungicides. Due to concern about the risks of environmental contamination, human, mainly children and animal toxicity and the emergence of fungal isolates resistant to fungicides, various researches has been development to obtain alternative techniques for a fungicides. The objectives of this work was to evaluate the effetives fix and essencial oils and biocontrol agents for the control of P. digitatum and G. citricarpa on Pera orange fruits in postharvest. Thus, were tested the fixed oils from Allium sativum, Copaifera langsdorffii, Eucalyptus spp. Azadirachta indica,and the essential oils of Pogostemon cablin, Mentha arvensis, Cymbopogon citratus, Ocimum basilicum var. Maria bonita, Romarinus officinalis, Lippia sidoides, Zingiber officinale, Citrus aurantifolia, Piper aduncum and Ocimum basilicum. In addition were also studied the following biocontrol agents: Bacillus subtilis (Serenade ®), Bacillus subtilis and Bacillus lichiniformes (Nemix ®), Pichia guilliermondii (L29), Sporobolomyces roseus (L41), Rhodotorula mucilagenosa (L17), Sporodiobolus pararoseus, Pichia spp. (L4-1), Derbaryomyces hansenii (L62), Pichia membranifaciens (L21) and a bacterium isolate of the orange. Both biocontrol agents as the oils, were tested in vivo and in vitro against both pathogens. For the assessment of activity of essential oils and antagonists in vivo in controlling P. digitatum were used Pera orange. Each fruit was wounded in two opposite points in the equatorial region, reaching the albedo. After the injury, the fruits were inoculated with 20 mL of conidial suspension of P. digitatum (105 conidia / mL), followed by immersion in a suspension of cells of each biocontrol agent in the concentration: ...(Complete abstract click electronic access below)

Orientador: Francisco Araújo Câmara / Banca: Edson Luiz Furtado / Banca: Regina Marta Evangelista / Banca: Euclides Schallenberger / Banca: Daniel Melo de Castro / Resumo: No modelo dominante de produção, o tomate (que integra o hábito alimentar da população em geral), demanda uso intensivo de agrotóxicos, por apresentar grande suscetibilidade a insetos e doenças durante a fase de cultivo. Assim, os agricultores têm dificuldade na produção orgânica, pela complexidade de problemas fitossanitários que esta espécie apresenta. O presente trabalho objetivou identificar cultivares de tomate que se adaptem ao cultivo agroecológico, e avaliar dois sistemas de produção, orgânico e biodinâmico, com técnicas alternativas de controle de pragas e doenças. A cultivar Epagri 19, foi selecionada do experimento de identificação de cultivares, e juntamente com a Epagri 17, foram as mais resistentes a problemas fitossanitários, sendo a Epagri 19 avaliada no sistema orgânico e biodinâmico com tratamentos fitossanitários alternativos. Constatou-se que todos os tratamentos alternativos foram eficientes no controle de doenças do tomateiro. O sistema biodinâmico apresentou menor severidade de doenças que o orgânico. Quanto à produtividade de tomate, não houve diferença entre os sistemas. Foram avaliados parâmetros de qualidade dos frutos de tomate que incluíram: perda de massa, textura, pH, sólidos solúveis, acidez titulável e açúcares redutores. Os sistemas de produção orgânico e biodinâmico, juntamente com a utilização de defensivos alternativos, e o uso de cultivares resistentes permitem o cultivo de tomate, menos dependente de agrotóxicos, não agredindo o meio ambiente e a saúde humana. / Abstract: In the dominant model of production, the tomato (which integrates the food habits of the population in general), demands an intensive use of agrochemicals, for its susceptibility to insects and diseases during cultivation phase. So, farmers meet dificulties in the organic method of production, because of the complexity of problems that this species presents. The purpose of the present work was to turn, to identify cultivars of tomato adapted to the organic and biodynamic methods of production, to evaluate these two systems, with alternative techniques for pest and disease control. The cultivars Epagri 19 and Epagri 17 were selected resistance due to there to pests and diseases. Epagri 19 was evaluated through the organic and biodynamic systems, with alternative treatments. It was verified that all of the alternative treatments were efficient in the control of diseases of the tomato. The biodynamic system presented a smaller severity of diseases than the organic. As to the productivity there was no difference between the systems. Parameters of quality of the tomato fruits have been evaluated, such as: weight loss, texture, pH, soluble solids, titratable acidity and reducing sugars. The organic and biodynamic production systems, together with the adoption of alternative treatments, and the use of resistant cultivars, allow the cultivation of tomatoes less dependent on pesticides, respecting the environment and the human health. / Doutor