Seed coat biochemistry and colour are highly variable in common bean (Phaseolus vulgaris) (syn. dry bean). Genetic studies of dry bean seed coat chemistry and colour have important implications in breeding efforts for improving nutrition and seed quality for consumer acceptance. The results of this thesis detail the phenotypic and genotypic characterization of seed coat post harvest darkening (PHD) in parents and progeny of crosses among them as well as the phenotypic characterization of seed coat condensed tannin (CT) accumulation in five genotypes of bean.<p> Seed coat PHD represents a problem for producers and consumers of several different market classes of dry bean. There are three post harvest darkening phenotypes: (i) non-darkening (ND), (ii) slow darkening (SD) and (iii) regular darkening (RD). The inheritance of PHD was determined by evaluating 28 populations derived from crosses between RD, SD and ND genotypes. Results suggest that at least two major, unlinked genes control the PHD trait in dry bean. Recessive epistasis with three phenotypic classes best explains the segregation ratios observed in populations from crosses between SD and ND parents. One gene, J, is responsible for whether a bean will darken and seeds of plants that are jj do not darken at all. Another gene, SD, influences the rate a seed coat will darken with seed from sdsd individuals darkening more slowly that those with the dominant SD allele. Quantitative evaluation of seed coat PHD demonstrated that there was a wide range of darkening within any given PHD phenotype. Crosses made between the ND x ND cross class resulted in F2 progeny that were all ND, however, a wide range of seed coat background colours was noted in the progeny. In several of the crosses made between ND x RD and SD x RD classes the resulting F1 progeny were all RD; however, a wide range of RD phenotypes were observed in the F2 progeny. These phenotypes are not likely due to quantitative trait loci (QTL) associated with the PHD trait, but rather a result of other chemical reactions occurring in the seed coat. Condensed tannins (CT; syn. proanthocyanidins), kaempferols, polyphenol oxidase (PPO) and possibly other compounds or enzymes may be interacting and causing this quantitative range within any given genotype as a function of environmental variability, genotype and their interaction. CT have been associated with PHD but are not responsible for the major difference between RD and SD lines. They may, however be responsible for the quantitative nature of the phenotype.<p> Condensed tannins can be harmful or beneficial to human health and the environment depending on the amount present and where it is found in the plant. Manipulating the production, accumulation and form of CT in the seed coat of dry bean would be beneficial to bean producers, consumers and breeders. This experiment quantitatively and qualitatively evaluated differences in patterns of CT accumulation in the seed coats of five genotypes of dry bean which exhibited low, medium or high concentrations of CT in their seed coats at maturity. Condensed tannin content was assessed from seeds harvested every other day from 6 40 days after flowering (DAF) using a modified BuOH-HCl assay. Results illustrated that CT accumulated as early in low CT genotypes as in high CT genotypes. CT content stabilized after 14 DAF in low CT genotypes. By contrast, CT content peaked then leveled off 30 DAF in moderate and high CT genotypes. A reduction in CT content in the higher CT lines was observed in the final stages of seed development.

The health maintaining properties of citrus consumption are attributed to the wide assortment of bioactive compounds. Consumption of grapefruit along with certain medications, however, is posing a risk of drug toxicity and side reactions. The first study involved isolation of bioactive furocoumarins with a combination of chromatographic techniques and synthesis. Five furocoumarins namely, dihydroxybergamottin, paradisin A, bergamottin, bergaptol and geranylcoumarin were isolated from grapefruit and series of furocoumarin monomers and paradisin A were synthesized. The second study involved influence of pre- and post-harvest factors on the levels of furocoumarins in grapefruit juice. Considerable differences were observed in the levels of these compounds in different grapefruit cultivars. Ray Red showed the lowest levels of all three furocoumarins and Duncan contains the highest amount of DHB and bergamottin, where as the highest levels of paradisin A was observed in Star Ruby. The highest levels of DHB and bergamottin were found in Flame cultivar grown in California. The changes in the levels of these furocoumarins during the season in Rio Red and Marsh White grapefruit cultivars were evaluated. The third study investigated biological activities of grapefruit juices and furocoumarins. Grapefruit and Pummelo juices were found to be potent inhibitors of cytochrome CYP3A4 and CYP2C9 isoenzymes at 5% concentration while CYP2D6 was less affected. Among the five furocoumarins tested, the inhibitory potency was in the order of paradisin A>dihydroxybergamottin>bergamottin>bergaptol>geranylcoumarin at 0.1 µM to 0.1 mM concentrations. A fourth study investigated the effect of furocoumarins on bacterial auto-inducer signaling, and found that furocoumarins are potent inhibitors of AI-1 and AI-2 activities at 0.01% concentration. In a fifth study, involving synthesized furocoumarin monomers and dimer on anti-proliferative activities on normal and cancer cell lines, furocoumarins found to be non-toxic to normal cells. However, bergamottin showed a significant anti-proliferative activity in HT-29 and MCF-7 cell lines. This dissertation indicates that furocoumarins are bioactive compounds from grapefruit juice with potent inhibitory property of major drug metabolizing cytochrome P450 isoenzymes. Furocoumarins show a considerable variation between varieties, location and season. These results corroborate the involvement of furocoumarins in grapefruit drug interaction.

Structural retention harvesting represents one of the most important recent silvicultural innovations and is widely practiced in the harvesting of mature boreal stands. Following structural retention harvests, mortality of retained trees is often dramatically elevated compared to pre-harvest stands. I examined tree mortality following structural retention harvests in the southeastern Yukon Territory, using dendrochronological techniques to quantify annual mortality. I estimated integrated losses in the first five years to be at least 17.3% of retained stems. Analysis of mortality type showed that windthrow was the most important post-harvest mortality mechanism. This study represents the first analysis of mortality responses following structural retention harvests in the northern extent of operational forestry in Canada. Rates of post-harvest tree mortality observed in this study are among the highest reported to date from managed Canadian boreal forests, indicating that greater attention must be given to post-harvest stand responses if sustainable forestry practices are desired.

Structural retention harvesting represents one of the most important recent silvicultural innovations and is widely practiced in the harvesting of mature boreal stands. Following structural retention harvests, mortality of retained trees is often dramatically elevated compared to pre-harvest stands. I examined tree mortality following structural retention harvests in the southeastern Yukon Territory, using dendrochronological techniques to quantify annual mortality. I estimated integrated losses in the first five years to be at least 17.3% of retained stems. Analysis of mortality type showed that windthrow was the most important post-harvest mortality mechanism. This study represents the first analysis of mortality responses following structural retention harvests in the northern extent of operational forestry in Canada. Rates of post-harvest tree mortality observed in this study are among the highest reported to date from managed Canadian boreal forests, indicating that greater attention must be given to post-harvest stand responses if sustainable forestry practices are desired.

<p>We hypothesize that South African medicinal plants contain compounds that can act in synergism with synthetic antifungal compounds. Four fungicides - Sporekill&trade / , Rovral&trade / , Terminator&trade / and Teldor&trade / at doses 0.1, 0.2, 0.4 and 0.8 mL L-1 and plant species Galenia africana, Elytropappus rhinocerotis and Tulbaghia violacea were tested aloneand in different combinations for their potency (efficacy) on radial growth inhibition of Botrytis cinerea strains on potato dextrose plates. Four doses of plant extract for each of the respective plant species were used. A total of 48 combinations were tested for each strain. Mixtures of plant extracts were far more effective in controlling strains compared to the individual components alone, representing significant levels of in vitro synergistic interactions. Combinations of these components represent an attractive future prospect for the development of new management strategies for controlling B. cinerea. Since the in vitro tests of these mixtures showed inhibitory activity, the mixtures were tested for activity in assays on Granny Smith apples. In vitro tests can be used to screen mixtures to obtain information on their inhibitory activity on a pathogen, however, the environmental conditions of the fruit and the ability of the pathogen to grow into the fruit cannot be simulated in vivo. A series of two-fold doses of medicinal plant extracts were combined with fungicides to conduct decay inhibition studies. The incidence of gray mold was significantly reduced by mixtures of plant extracts and fungicides. Under conditions similar to those in commercial storage, a drench treatment with G. africana and Rovral&trade / significantly (p=0.05) inhibit gray mold on the apples and was more effective than the plant extract and fungicide alone. The treatments exerted synergistic effects and were markedly better than the components applied alone. The wound colonization assay was used for optimal decay control. In a drench, much higher volumes of the treatments are used to ensure that the components of the suspension are deposited evenly over the entire fruit surface. Drenching of fruit to apply other chemicals is an established practise in the pome (fleshy) fruit industry, and simplifies the commercial application of the mixtures, as no additional infrastructure at commercial packing houses will be required. This approach not only makes it possible to reduce fungicide concentrations while maintaining adequate decay control, but also ensures a reduction of the chemical residue on the fruit.</p>

No description available.

<p>We hypothesize that South African medicinal plants contain compounds that can act in synergism with synthetic antifungal compounds. Four fungicides - Sporekill&trade / , Rovral&trade / , Terminator&trade / and Teldor&trade / at doses 0.1, 0.2, 0.4 and 0.8 mL L-1 and plant species Galenia africana, Elytropappus rhinocerotis and Tulbaghia violacea were tested aloneand in different combinations for their potency (efficacy) on radial growth inhibition of Botrytis cinerea strains on potato dextrose plates. Four doses of plant extract for each of the respective plant species were used. A total of 48 combinations were tested for each strain. Mixtures of plant extracts were far more effective in controlling strains compared to the individual components alone, representing significant levels of in vitro synergistic interactions. Combinations of these components represent an attractive future prospect for the development of new management strategies for controlling B. cinerea. Since the in vitro tests of these mixtures showed inhibitory activity, the mixtures were tested for activity in assays on Granny Smith apples. In vitro tests can be used to screen mixtures to obtain information on their inhibitory activity on a pathogen, however, the environmental conditions of the fruit and the ability of the pathogen to grow into the fruit cannot be simulated in vivo. A series of two-fold doses of medicinal plant extracts were combined with fungicides to conduct decay inhibition studies. The incidence of gray mold was significantly reduced by mixtures of plant extracts and fungicides. Under conditions similar to those in commercial storage, a drench treatment with G. africana and Rovral&trade / significantly (p=0.05) inhibit gray mold on the apples and was more effective than the plant extract and fungicide alone. The treatments exerted synergistic effects and were markedly better than the components applied alone. The wound colonization assay was used for optimal decay control. In a drench, much higher volumes of the treatments are used to ensure that the components of the suspension are deposited evenly over the entire fruit surface. Drenching of fruit to apply other chemicals is an established practise in the pome (fleshy) fruit industry, and simplifies the commercial application of the mixtures, as no additional infrastructure at commercial packing houses will be required. This approach not only makes it possible to reduce fungicide concentrations while maintaining adequate decay control, but also ensures a reduction of the chemical residue on the fruit.</p>

No description available.

No description available.

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: ‘Triumph’ persimmon production in South Africa is export driven and the profitability of the industry is largely dependent on consumer demand and supermarket shelf space in the European market. In order to realise high returns, it is important to advance harvest maturity to attain early fruit that arrives on the market prior to European summer fruits. In addition, market feedback suggests that fruit picked during the second half of the harvesting period stores poorly and rapidly softens during shelf life. It is important to establish whether this is the case. The effect of paclobutrazol (PBZ) application rate on fruit maturity and keeping quality, return bloom and vegetative growth was investigated over two seasons. Advanced harvest maturity was attained at a compromise of reduced fruit storage quality and stunted growth with the severity of the compromise increasing with increasing PBZ application rate. To advance harvest maturity while maintaining acceptable keeping quality, PBZ application at 0.75 ml per plant is recommended although effects on harvest maturity will not persist into the subsequent season as found at higher application rates. Prohexadione-calcium (P-Ca) as an alternative for PBZ in advancing harvest maturity was evaluated over two seasons. A positive response to three foliar applications of P-Ca at 200 mg·L-1 was noticed in the first season. In the second season, a single application of P-Ca at 300 mg·L-1 two weeks before harvest significantly advanced harvest maturity. Due to the rapid metabolism of P-Ca in the plant, it is unlikely that growth in the subsequent season will be affected. Based on these results, the persimmon industry will undertake commercial trials in the 2012 season to further assess the efficacy of P-Ca application in advancing harvest maturity. The effect of various rest breaking agents (RBAs) on bud break, flowering, fruit maturity and quality as well as vegetative growth was assessed for one season. RBAs did not increase or advance bud break and flowering. Consequently, yield and harvest maturity were unaffected by the treatments. The ineffectiveness of the RBAs could be due to the low application rates used or the fulfilment of the chilling requirement prior to treatment application. An experiment was carried out to determine whether storability and shelf-life differ between “early” and “late” production areas in South Africa as well as between orchards within these areas. The data indicated that fruit colour is a good maturity parameter and indicator of fruit storability. However, “late” fruit were about 1 kg softer than “early” fruit at the same colour chart value. We therefore recommend that fruit from late regions are harvested at colour chart values of 5 and 6 (yellow-green) instead of 3 and 4. Fruit from “late” orchards as well as GA3-treated fruit with a colour chart value of 3 and less should be culled due to the high propensity (>20%) of these fruit to become soft during storage and shelf life. A delay in 1-MCP treatment and interruption of the cold chain considerably increased fruit softening during storage and shelf-life. Further research is required to verify this result. / AFRIKAANSE OPSOMMING: ‘Triumph’ persimmon produksie in Suid-Afrika is uitvoergedrewe en die winsgewendheid van die bedryf is grootliks afhanklik van verbruikervraag en supermark spasie in die Europese mark. Ten einde hoë pryse te realiseer, is dit belangrik om ʼn vroeë oes te verkry sodat vrugte voor die Europese somervrugte op die mark beland. Mark terugvoer dui verder daarop dat vrugte wat tydens die tweede helfte van die oesperiode gepluk word, swakker opberg en vinnig sag word gedurende op die rak. Dit is belangrik om vas te stel of hierdie waarneming juis is. Die effek van paklobutrazol (PBZ) toedieningshoeveelheid op vrugrypwording en - houvermoë, opvolgblom en vegetatiewe groei is oor twee seisoene ondersoek. Oesrypheid is vervroeg, maar tot nadeel van vrughouvermoë en vegetatiewe groei. Die omvang van die negatiewe effekte van PBZ het toegeneem met ʼn toename in toedieningshoeveelheid. Ten einde oesrypheid te vervroeg terwyl aanvaarbare houvermoë behou word, word toediening van PBZ teen 0.75 ml per plant aanbeveel alhoewel die effek op oesrypheid anders as die geval met hoër toedieningshoeveelhede nie in die opeenvolgende seisoen sal voortduur nie. Proheksadioon-kalsium (P-Ca) as alternatief tot PBZ om oesrypheid te vervroeg is oor twee seisoene gee-valueer. ʼn Positiewe effek op vrugrypwording is in die eerste seisoen verkry met drie blaartoedienings van P-Ca teen 200 mg·L-1. In die tweede seisoen is oesrypheid betekenisvol vervroeg deur ʼn enkel toediening van 300 mg·L-1 P-Ca ʼn maand voor oes. Vanweë hierdie resultate gaan die persimmonbedryf in die 2012 seisoen kommersiële proewe onderneem om die effektiwiteit van P-Ca om oes te vervroeg, verder te ondersoek. Die effek van verskeie rusbrekende middels (RBAs) op bot, blom, vrugrypheid, vrugkwaliteit en vegetatiewe groei is vir een seisoen ondersoek. RBAs het bot en blom vervroeg of vermeerder nie en het daarom ook geen effek op produksie en oesrypheid gehad nie. Die oneffektiwiteit van die RBAs kan moontlik toegeskryf word aan die lae toedieningsvlakke wat gebruik is of aan die kouebehoefte wat bevredig is voor toediening van RBAs. ʼn Eksperiment is gedoen om vas te stel of die opberging- en houvermoë van vrugte verskil tussen “vroeë” en “laat” produksieareas in Suid-Afrika en ook tussen boorde in hierdie areas. Die data dui daarop dat vrugkleur ʼn goeie rypheidsparameter en indikator van opbergingsvermoë is. Vrugte van laat areas was egter omtrent 1 kg sagter as vrugte van vroeë areas van dieselfde kleur. Ons beveel gevolglik aan dat vrugte van laat areas by ʼn kleurkaartwaarde van 5 tot 6 (geelgroen) geoes word eerder as by 3 tot 4. Vrugte van laat boorde sowel as vrugte wat met GA3 behandel is met ʼn kleurkaartwaarde van 3 en laer moet afgradeer word weens die hoë geneigdheid (>20%) van hierdie vrugte om sag te word tydens opberging en op die rak. Uitstel van 1-MCP behandeling en die onderbreking van die koueketting veroorsaak ʼn aansienlike toename in sagte vrugte tydens opberging en op die rak. Verdere navorsing word benodig om hierdie resultaat te verifieer.