The biochemical changes taking place during soybean seed development and gennination, and some aspects of desiccation tolerance were assessed with reference to lipid peroxidation and antioxidant systems. During nonnal seed development, fresh weight and dry weight increased between 20 and 50 days after flowering (DAF), concomitant with the accumulation of triacylglycerols and sugar reserves, after which dry weight remained almost unchanged, and fresh weight decreased. Seed moisture content decreased rapidly during the last stages of development. High levels of lipid peroxidation were evident between 20 and 45 DAF, and decreased thereafter. An examination of antioxidant systems revealed that whereas total glutathione levels accumulated continuously throughout the 80 days of seed development, both dehydroascorbic acid (DHA) reductase and ascorbate free radical (AFR) reductase increased concurrently with the increase in total ascorbate content, and the overall levels did not decrease markedly during maturation drying. Ascorbate peroxidase (ASC POD) activity was high during the period ofgreatest ascorbate accumulation. Both catalase (CAn and superoxide dismutase (SOD) activities increased progressively during early seed development (20-40 DAF), but showed variable patterns of change during maturational drying, in marked contrast to ASC POD which declined from 40 DAF to undetectable levels at 70 DAF. An assessment of the relationship between the antioxidant systems and lipid peroxidation was made during imbibition and gennination, as it has been suggested that controlling free radicals was a critical event in early imbibition. Unexpectedly, lipid peroxidation increased progressively in both seeds and isolated axes, and were eight-fold higher at 48 hours of imbibition compared to dry tissues. A progressive, and co-ordinated, increase in CAT, total glutathione, total ascorbate pool, guaiacol POD, ASC POD, and SOD appeared to parallel the rise in lipid peroxidation in both whole seeds and axes. Variable responses were evident between seeds and axes for the enzymes AFR reductase and DHA reductase In order to gain a further insight into the dynamics of desiccation-tolerance and desiccationsensitivity, imbibing seeds were subjected to an unscheduled dehydration treatment, and then rehydrated for up to 24 hours. During these hydration-dehydration-rehydration (H-D-R) treatments, changes in lipid peroxidation and antioxidant systems were measured. Concurrent with the loss of viability in the axes of seeds dehydrated after 24 and 36 hours of imbibition, there were increases in both lipid peroxidation and solute leakage. Unscheduled drying was seen to be a critical stage, as intolerant axes showed four- to eightfold increases in lipid peroxidation, which were only partially reduced on subsequent rehydration. Tolerant axes, on the other hand, were able to maintain low, basal levels of lipid hydroperoxides on drying. The relationship between these observations and the antioxidant systems showed that the antioxidant enzymes CAT, ASC POD, AFR reductase, DHA reductase, guaiacol POD and SOD declined markedly during the unscheduled drying, whereas GSH and ASC declined only slightly. On rehydration, most of the enzymes, total glutathione, and total ascorbate pool increased, the only exception being the loss of ASC POD activity. ORA reductase, which was seen to decrease as a part of nonnal gennination, declined progressively also in H-D-R treatments. These results suggested that loss of viability was not attributable to a decline of the antioxidant systems but rather to the combined deleterious effects of increased lipid peroxidation, and a generalized and moderately compromised antioxidant system. These studies have indicated that the occurrence of lipid peroxidation can be seen as a nonnal part of seed development and gennination. The H-D-R studies, on the other hand, supported the concept that the balance between peroxidation reactions and the protective systems was critical to the development of desiccation tolerance. / Thesis (Ph.D.)-University of Natal, Durban, 2003.

Phytophthora infestans (Mont) de Bary is a devastating pathogen in potato producing regions around the world. Populations of the organism in Canada shifted during the mid-1990’s as the US-1 strain (A1, metalaxyl-sensitive) was displaced by the highly aggressive, US-8 strain (A2, metalaxyl-insensitive). An increase in the incidence and severity of late blight has followed. Late blight is controlled by cultural practices aimed at eliminating disease sources and by the application of foliar fungicides. Tubers can become infected at harvest from contact with blighted vines leading to severe losses in storage. In many production areas, growers desiccate vines two to three weeks prior to harvest to reduce late blight tuber rot. However, in Manitoba, because of the loss of potential yield that results from vine killing prior to harvest in a late maturing cultivar such as Russet Burbank, growers are reluctant to adopt this practice. The objective of this study was to develop recommendations for preharvest management practices that reduce storage losses due to late blight. Field trials were conducted in 1997 and 1998 to investigate the effect of vine desiccation with diquat and/or a late season application of chlorothalonil and copper hydroxide on yield, processing quality, and disease development in storage. Desiccating vines with diquat two weeks prior to harvest reduced yield and tuber size. Compared to the untreated control, the largest reductions in marketable yield were observed for the early September harvest. By the late September harvest, however, the effect of vine killing in reducing marketable yield was less apparent. Specific gravity was lower in the vine killed treatment for all harvest dates in 1997 and in the early and mid September harvests in 1998. Vine killing did not contribute to elevated levels of reducing sugars or consistently darker fry colour at harvest or during storage. Skin-set was improved when vines were desiccated for all harvest dates in 1997 and at the early September harvest date in 1998. Vine killing reduced tuber rot in storage caused by Fusarium dry rot and Pythium leak for the early and mid September harvest dates in 1997. The incidence of late blight tuber rot was reduced in storage for the early September harvest in 1998 when vines were desiccated. The late-season application of chlorothalonil and copper hydroxide did not reduce tuber rot in storage in storage either year. Results from this study indicate that vine killing two weeks before an early to mid- September harvest is not recommended in Manitoba because of reductions in yield and specific gravity. Alternative management practices to reduce late blight tuber rot in storage should be investigated.

Phytophthora infestans (Mont) de Bary is a devastating pathogen in potato producing regions around the world. Populations of the organism in Canada shifted during the mid-1990’s as the US-1 strain (A1, metalaxyl-sensitive) was displaced by the highly aggressive, US-8 strain (A2, metalaxyl-insensitive). An increase in the incidence and severity of late blight has followed. Late blight is controlled by cultural practices aimed at eliminating disease sources and by the application of foliar fungicides. Tubers can become infected at harvest from contact with blighted vines leading to severe losses in storage. In many production areas, growers desiccate vines two to three weeks prior to harvest to reduce late blight tuber rot. However, in Manitoba, because of the loss of potential yield that results from vine killing prior to harvest in a late maturing cultivar such as Russet Burbank, growers are reluctant to adopt this practice. The objective of this study was to develop recommendations for preharvest management practices that reduce storage losses due to late blight. Field trials were conducted in 1997 and 1998 to investigate the effect of vine desiccation with diquat and/or a late season application of chlorothalonil and copper hydroxide on yield, processing quality, and disease development in storage. Desiccating vines with diquat two weeks prior to harvest reduced yield and tuber size. Compared to the untreated control, the largest reductions in marketable yield were observed for the early September harvest. By the late September harvest, however, the effect of vine killing in reducing marketable yield was less apparent. Specific gravity was lower in the vine killed treatment for all harvest dates in 1997 and in the early and mid September harvests in 1998. Vine killing did not contribute to elevated levels of reducing sugars or consistently darker fry colour at harvest or during storage. Skin-set was improved when vines were desiccated for all harvest dates in 1997 and at the early September harvest date in 1998. Vine killing reduced tuber rot in storage caused by Fusarium dry rot and Pythium leak for the early and mid September harvest dates in 1997. The incidence of late blight tuber rot was reduced in storage for the early September harvest in 1998 when vines were desiccated. The late-season application of chlorothalonil and copper hydroxide did not reduce tuber rot in storage in storage either year. Results from this study indicate that vine killing two weeks before an early to mid- September harvest is not recommended in Manitoba because of reductions in yield and specific gravity. Alternative management practices to reduce late blight tuber rot in storage should be investigated.

Master of Science / Department of Agronomy / P. V. Vara Prasad / In many countries producers have been growing varieties of hard white winter (HWW) wheat since decades. The cause of concern is most varieties of HWW wheat are susceptible to pre-harvest sprouting (PHS) which affects grain quality. Environmental conditions like high humidity, precipitation, heavy dew and hormonal activity at physiological maturity stimulate PHS in HWW. To alleviate these conditions research was carried out at KSU. KS01HW163-4, a sprouting tolerance line was crossed with Heyne, a sprout susceptible cultivar. A total of 224 doubled haploid (DH) lines thus produced were phenotyped in the present study through experiments conducted in controlled environments. The objectives of this research were to (i) characterize and phenotype the doubled haploid lines for PHS in controlled environments; (ii) understand the impact of growth environment (high temperature and/or drought) and; (iii) impact of exogenous application of growth hormones on tolerance to pre-harvest sprouting in the parental lines of the doubled haploid population. The phenotypic data collected from this research will be ultimately combined with the genotypic data to identify DNA markers related to PHS tolerance and provide DNA markers for marker assisted selection. Based on my results of the germination percentages from the 224 DH lines, the population was distributed as susceptible, and tolerant to PHS showing a bimodal distribution and X[superscript]2 analysis indicating a complimentary gene action. From the study of the influence of environmental factors on PHS, my results confirmed a definite influence of stress on sprouting. Under optimum temperature (OT), KS01HS163-4 was tolerant to PHS, but at HT and/or drought it became susceptible to PHS. Growth under stressed conditions changed the tolerance levels to PHS. Seed dry-weight, and harvest index were also influenced negatively due to stress. Therefore multi-location tests must be conducted with variable environments to test the stability of a variety to PHS. From the study of the influence of phytohormones on PHS, the results suggest that tolerance to sprouting was seen in seeds from plants sprayed with abscisic acid (ABA) and paclobutrazol (GA-inhibitor) treatments where as those from gibberellic acid (GA) treatment showed susceptibility to sprouting.

Mamões \'Golden\' possuem importância econômica e social no Brasil com destaque dentre as frutas mais exportadas e consumidas. Porém, possuem curta vida útil e distintos comportamentos pós-colheita, bem como distúrbio do amolecimento precoce (DAP) com ocorrência esporádica. Isso culmina na dificuldade em alavancar as pesquisas de tecnologias de conservação. A hipótese de que o DAP tenha como causa fatores pré-colheita e o desbalanço hormonal, envolvendo a auxina (AIA), implicou no desenvolvimento deste estudo. Dentro deste contexto, o objetivo deste trabalho foi investigar o comportamento dos mamoeiros \'Golden\' diante de adversidades climáticas, simuladas com excesso de irrigação, e diante do desbalanço hormonal, induzido pela aplicação pré-colheita de reguladores vegetais. Para tal propósito o projeto foi desenvolvido em três etapas. A primeira foi com a avaliação do comprometimento fotossintético e nutricional de mamoeiros \'Golden\' em função de condições climáticas e estresse hídrico. A segunda foi com a avaliação física, química, fisiológica e níveis de AIA dos mesmos mamões \'Golden\' da primeira etapa. E a terceira foi com análise dos frutos na pós-colheita após aplicação de reguladores vegetais na pré-colheita [1-metilciclopropano (1-MCP), etefon e ácido 2,3,5-triiodo benzoico (TIBA)]. Na primeira e segunda etapa os mamoeiros foram conduzidos na região norte do Espírito Santo durante os meses de maio e outubro de 2012. Os tratamentos com lâminas de irrigação foram: controle = 33 mm de água e excesso = 70,6 mm de água durante 5 a 7 dias aplicados mensalmente. A atividade fotossintética e a nutrição mineral foram avaliadas logo após os tratamentos. Os frutos para avaliação na segunda etapa foram colhidos após 5 ou 7, 20 e 30 dias. As avaliações dos frutos foram durante 12 dias a 10 ± 1ºC e 85 ± 5% de UR. Na terceira etapa os mamoeiros foram conduzidos entre abril de 2012 e maio de 2013 em área experimental da ESALQ/USP em Piracicaba/SP. Os reguladores vegetais foram aplicados quando os frutos atingiram 120 dias após a antese. Os frutos foram colhidos quando a cor da casca atingiu o estádio 1 e foram analisados no estádio 5. Diante das duas primeiras etapas foi possível observar que as plantas e os frutos dos mamoeiros não apresentaram o DAP pelo excesso de água isoladamente, mas sim por um conjunto de fatores como temperaturas elevadas, altos índices pluviométricos, alto déficit de pressão de vapor e desbalanço nutricional. Porém, houve comprometimento do aparato fotossintético identificado, principalmente, pelo teste transiente da clorofila a, redução dos níveis de AIA e de 1-aminociclopropano-1-ácido carboxílico (ACC) naqueles frutos com excesso de irrigação. Os resultados da terceira etapa demonstraram que a formação fisiológica dos frutos tem relação com os graus dias acumulados e que as mudanças no comportamento pós-colheita, possivelmente, ocorrem em maior proporção em função dos teores de etileno endógeno do que dos teores de AIA livre. / \'Golden\' papayas have economic and social importance in Brazil, especially among the most exported and consumed fruit. However, have a short shelf life and postharvest distinct behaviors, as well as sporadic occurrence of \"early softening disorder\" (ESD). This culminates in difficulty leveraging research conservation technologies. The hypothesis that ESD has a cause preharvest factors and hormonal imbalance involving auxin (IAA) resulted in the development of this study. Within this context, the aim of this study was to investigate the behavior of papaya \'Golden\' before climatic adversities, simulated with excessive irrigation, and before the hormonal imbalance induced by preharvest application of plant growth regulators. For this purpose the project was developed in three stages. The first was to review the photosynthetic and nutritional impairment of papaya \'Golden\' due to climatic conditions and drought stress. The second was with the physical, chemical, and physiological assessment of these levels IAA \'Golden\' papaya the first step. And the third was to analyze the fruits after application of plant growth regulators on preharvest [methylcyclopropane - 1 (MCP - 1), ethephon and 2,3,5 - triiodo benzoic acid (TIBA)]. In the first and second stage, papayas were conducted in the northern region of the Espírito Santo during the months of May and October 2012. The irrigation treatments were: control = 33 mm and excess water = 70.6 mm water for 5 or 7 days applied monthly. Photosynthetic activity and mineral nutrition were evaluated after treatments. Fruit for evaluation in the second stage were harvested after 5 or 7, 20 and 30 days. The fruits of the reviews were storage for 12 days at 10 ± 1 ºC and 85 ± 5 % RH. In the third stage, papayas were conducted between April 2012 and May 2013 in an experimental field of ESALQ/USP in Piracicaba/SP. Growth regulators were applied when fruit reached 120 days after anthesis. Fruit were harvested when the color of the shell reached the stage 1 and were analyzed in stage 5. Given the first two stages was observed that plants and fruit did not show ESD by excess water alone, but by a set of factors such as high temperatures, heavy rainfall, high vapor pressure deficit and nutritional imbalance. However, there was impairment of the photosynthetic apparatus identified mainly by the transient testing chlorophyll a reduction in the levels of IAA and a 1-aminocyclopropane-carboxylic acid 1 (ACC) in fruit over- irrigation. Third stage showed that physiological fruit formation is related to accumulated growing degree days and those changes in post-harvest behavior, possibly occur to a greater extent depending on the levels of endogenous ethylene than IAA free.

Mamões \'Golden\' possuem importância econômica e social no Brasil com destaque dentre as frutas mais exportadas e consumidas. Porém, possuem curta vida útil e distintos comportamentos pós-colheita, bem como distúrbio do amolecimento precoce (DAP) com ocorrência esporádica. Isso culmina na dificuldade em alavancar as pesquisas de tecnologias de conservação. A hipótese de que o DAP tenha como causa fatores pré-colheita e o desbalanço hormonal, envolvendo a auxina (AIA), implicou no desenvolvimento deste estudo. Dentro deste contexto, o objetivo deste trabalho foi investigar o comportamento dos mamoeiros \'Golden\' diante de adversidades climáticas, simuladas com excesso de irrigação, e diante do desbalanço hormonal, induzido pela aplicação pré-colheita de reguladores vegetais. Para tal propósito o projeto foi desenvolvido em três etapas. A primeira foi com a avaliação do comprometimento fotossintético e nutricional de mamoeiros \'Golden\' em função de condições climáticas e estresse hídrico. A segunda foi com a avaliação física, química, fisiológica e níveis de AIA dos mesmos mamões \'Golden\' da primeira etapa. E a terceira foi com análise dos frutos na pós-colheita após aplicação de reguladores vegetais na pré-colheita [1-metilciclopropano (1-MCP), etefon e ácido 2,3,5-triiodo benzoico (TIBA)]. Na primeira e segunda etapa os mamoeiros foram conduzidos na região norte do Espírito Santo durante os meses de maio e outubro de 2012. Os tratamentos com lâminas de irrigação foram: controle = 33 mm de água e excesso = 70,6 mm de água durante 5 a 7 dias aplicados mensalmente. A atividade fotossintética e a nutrição mineral foram avaliadas logo após os tratamentos. Os frutos para avaliação na segunda etapa foram colhidos após 5 ou 7, 20 e 30 dias. As avaliações dos frutos foram durante 12 dias a 10 ± 1ºC e 85 ± 5% de UR. Na terceira etapa os mamoeiros foram conduzidos entre abril de 2012 e maio de 2013 em área experimental da ESALQ/USP em Piracicaba/SP. Os reguladores vegetais foram aplicados quando os frutos atingiram 120 dias após a antese. Os frutos foram colhidos quando a cor da casca atingiu o estádio 1 e foram analisados no estádio 5. Diante das duas primeiras etapas foi possível observar que as plantas e os frutos dos mamoeiros não apresentaram o DAP pelo excesso de água isoladamente, mas sim por um conjunto de fatores como temperaturas elevadas, altos índices pluviométricos, alto déficit de pressão de vapor e desbalanço nutricional. Porém, houve comprometimento do aparato fotossintético identificado, principalmente, pelo teste transiente da clorofila a, redução dos níveis de AIA e de 1-aminociclopropano-1-ácido carboxílico (ACC) naqueles frutos com excesso de irrigação. Os resultados da terceira etapa demonstraram que a formação fisiológica dos frutos tem relação com os graus dias acumulados e que as mudanças no comportamento pós-colheita, possivelmente, ocorrem em maior proporção em função dos teores de etileno endógeno do que dos teores de AIA livre. / \'Golden\' papayas have economic and social importance in Brazil, especially among the most exported and consumed fruit. However, have a short shelf life and postharvest distinct behaviors, as well as sporadic occurrence of \"early softening disorder\" (ESD). This culminates in difficulty leveraging research conservation technologies. The hypothesis that ESD has a cause preharvest factors and hormonal imbalance involving auxin (IAA) resulted in the development of this study. Within this context, the aim of this study was to investigate the behavior of papaya \'Golden\' before climatic adversities, simulated with excessive irrigation, and before the hormonal imbalance induced by preharvest application of plant growth regulators. For this purpose the project was developed in three stages. The first was to review the photosynthetic and nutritional impairment of papaya \'Golden\' due to climatic conditions and drought stress. The second was with the physical, chemical, and physiological assessment of these levels IAA \'Golden\' papaya the first step. And the third was to analyze the fruits after application of plant growth regulators on preharvest [methylcyclopropane - 1 (MCP - 1), ethephon and 2,3,5 - triiodo benzoic acid (TIBA)]. In the first and second stage, papayas were conducted in the northern region of the Espírito Santo during the months of May and October 2012. The irrigation treatments were: control = 33 mm and excess water = 70.6 mm water for 5 or 7 days applied monthly. Photosynthetic activity and mineral nutrition were evaluated after treatments. Fruit for evaluation in the second stage were harvested after 5 or 7, 20 and 30 days. The fruits of the reviews were storage for 12 days at 10 ± 1 ºC and 85 ± 5 % RH. In the third stage, papayas were conducted between April 2012 and May 2013 in an experimental field of ESALQ/USP in Piracicaba/SP. Growth regulators were applied when fruit reached 120 days after anthesis. Fruit were harvested when the color of the shell reached the stage 1 and were analyzed in stage 5. Given the first two stages was observed that plants and fruit did not show ESD by excess water alone, but by a set of factors such as high temperatures, heavy rainfall, high vapor pressure deficit and nutritional imbalance. However, there was impairment of the photosynthetic apparatus identified mainly by the transient testing chlorophyll a reduction in the levels of IAA and a 1-aminocyclopropane-carboxylic acid 1 (ACC) in fruit over- irrigation. Third stage showed that physiological fruit formation is related to accumulated growing degree days and those changes in post-harvest behavior, possibly occur to a greater extent depending on the levels of endogenous ethylene than IAA free.

Thesis (MScAgric)--University of Stellenbosch, 1994 / 127 Leaves printed single pages, preliminary pages i-viii and numberd pages 1-118.Includes bibliography,tables and figures. / Date on t.p.: Dec. 1994. / ENGLISH ABSTRACT: Effects of pH,sucrose, boric acid and temperature on in vitro germination of pollen of Protea repens (L.) L. cv. 'Embers' were investigated in hanging-drop culture to establish optimum conditions for germination. Optimum values were found within ranges pH: 5 - 8, sucroseconcentration:0.4 - 0.7 M, boric acid concentration:50 - 500 mg.e-1 , and incubation temperature: 5 - 30°C. Storage temperature and humidity on pollen viability was studied in four Pro tea clones. Pollen was stored at a range of temperatures and relative humidities for up to one year and tested for ability to germinate in vitro. Pollen of P. repens cv. 'Sneyd', P. eximia cv. 'Fiery Duchess' andP. magnifica clone 'T 84 07 OS', stored in liquid nitrogen (-196°C) and in a freezer (-14° to -18°C), retained a germination percentage as high as that of fresh pollen regardless of humidity. The study showed that long-term storage of protea pollen is not feasible at temperatures above O°C. The correlations between the fluorochromatic reaction (FCR) and germinability were found to be low and nonsignificant. Fifteen month old cryopreserved 'Sneyd' pollen was shown to retain its ability to fertilize and set seed equal to that of fresh pollen. 'Sneyd', 'Fiery Duchess' and 'T 84 07 OS' pollen could be repeatedly thawed and frozen in liquid nitrogen before its germinability in vitro decreased. The morphology and size of Protea pollen was studied, using light and scanning electron microscopy. Polymorphic grains were observed in two interspecific hybrids. Very small differences in pollen grain size were recorded between clones/species. The male fertility of 25 interspecific Pro tea hybrids, based on in vitro pollen germinability, was investigated. The majority of hybrids were found to be sufficiently fertile to be used in a breeding programme. Pistil structure and pollen tube pathways were investigated in 'Sneyd' using light and scanning electron microscopy. The pistil had four distinct regions, consisting of the stigma, the vertebra-shaped upper style, the heart-shaped lower style, and the ovary. The pistil had a stylar canal along its entire length and this canal was also the route by which pollen tubes grew to the ovary. Very low numbers of pollen tubes reached the ovary. The breeding system of 'Sneyd' and 'Fiery Duchess' were determined from pollen tube and seed set data, after controlled hand-pollinations. Both clones were found to be fully selfcompatible. Very low percentages autogamous seed set were recorded. Interspecific crosses had a low success rate. An incompatibility reaction probably occurred on the stigma and/or in the upper style regions.The attainment of maximum stigma receptivity of two Protea cultivars was investigated by means of seed set experiments, pollen tube growth observations and measurement of the degree of opening and closing of the stigmatic groove. Both cultivars were found to be protandrous. The maximum stigmatic groove width of both cultivars never exceeded the pollen grain diameter. It was concluded that Protea spp. must be hand-pollinated two to six days after anthesis in order to obtain maximum seed set; while for the observations of pollen tubes in the ovary, inflorescences must not be harvested before seven days after pollination. / AFRIKAANSE OPSOMMING: Ten einde 'n optimale medium vir die in vitro-ontkieming van Protea-stuifmeel te ontwikkel, is die effek van pH, sukrose, boorsuur, en temperatuur op die in vitro-ontkieming van Protea repens (L.) L. cv. 'Embers'-stuifmeel deur middel van die hangdruppel-metode ondersoek. Die volgende reekse van veranderlikes wat getoets is, is as optimaal gevind; pH: 5 - 8, sukrosekonsentrasie: 0.4 - 0.7 M, boorsuurkonsentrasie: 50 - 500 mg.e-1 en inkubasietemperatuur: 5 - 30°C. Die invloed van bergingstemperatuur en humiditeit op stuifmeel-Iewenskragtigheid is in vier Protea-klone ondersoek. Stuifmeel is gestoor by 'n reeks temperature en relatiewe humiditeite vir tot eenjaar, en vir in vitro-ontkiemingsvermoe getoets.' Stuifmeel van P. repens <?v. 'Sneyd', P. eximia cv. 'Fiery Duchess', en P. magnifica kloon'T 84 07 OS', in vloeibare stikstof (-196°C) en in 'n vrieskas (-14° tot - 18°C) geberg, het 'n ontkiemingspersentasie gelykstaande aan die van vars stuifmeel gehandhaaf, ongeag van die humiditeit. Hierdie studie het verder aangetoon dat langtermynberging van Protea-stuifmeel bokant O°C me die moeite werd is me. Die korrelasie tussen die fluorochromatiese reaksie (FCR) en ontkieming was laag en me betekemsvol me. 'Sneyd' -stuifmeel wat vir 15 maande in vloeibare stikstof gestoor is, het die bevrugtings- en saadsetvermoe gelykstaande aan vars stuifmeel behou. 'Sneyd', 'Fiery Duchess' en 'T 84 07 OS'-stuifmeel kon herhaaldelik in vloeibare stikstof gevries en ontdooi word voordat hul ontkiemingsvermoe afgeneem het. Die morfologie en grootte van Proteastuifmeel is deur middel van lig- en skandeerelektronmikroskopie bestudeer. Polimorfiese stuifmeelkorrels is in twee interspesie-hibriede waargeneem. Baie klein verskille in stuifmeelkorrelgroottes het tussen klone/spesies voorgekom. Die manlike vrugbaarheid van 25 Protea-interspesiehibriede, gebaseer op die in vitro-ontkiembaarheid, is ondersoek. Dit is gevind dat die meerderheid hibriede 'n voldoende graad van vrugbaarheid het om in 'n teelprogram te gebruik. Die stamperstruktuur en stuifmeelbuiswee in P. repens is deur middel van lig- en skandeer-elektronmikroskopie ondersoek. Die stamper bestaan uit vier kenmerkende gebiede, naamlik die stempel, die werwelvormige bo-styl, die hartvormige onderstyl, en die vrugbeginsel. Die stamper het 'n stylkanaal regdeur die totale lengte van die stamper, en hierdie kanaal is ook die weg waarvolgens stuifmeelbuise na die vrugbeginsel gegroei het. Min stuifmeelbuise het die vrugbeginsel bereik. Die teelsisteem van 'Sneyd' en 'Fiery Duchess' is deur middel van stuifmeelbuis- en saadsetdata na gekontroleerde handbestuiwings ondersoek. Beide kIone was ten volle selfverenigbaar. Die persentasie outogame saadset was baie laag. Interspesiekruisings het 'n baie lae sukses gehad. Dit is voorgestel dat die onverenigbaarheidsreaksie in die stempel en/of in die bopunt van die styl plaasvind. Die bereiking van maksimum stempelontvanklikheid van twee Protea-cultivars is deur middel van saadseteksperimente, stuifmeelbuisdata en waarnemings van die oop- en toemaak van die stempelgroef ondersoek. Beide cultivars was protandries. Die maksimum stempelgroefwydte het nooit die stuifmeelkorreldeursnee oorskry nie. Dit is afgelei dat Protea-spesies twee tot ses dae na antese handbestuif moet word vir optimale saadset. Vir die waarneming van stuifmeelbuise in die vrugbeginsel, moet bloeiwyses nie voor sewe dae na bestuiwing geoes word nie.

Hormesis is a dose response phenomenon where low doses of a stress bring about a positive response in the organism undergoing treatment. UV-C hormesis has been known for over three decades and has a broad range of benefits on postharvest produce. Benefits include increased nutritional content, delayed chlorophyll degradation and disease resistance. The beneficial effects have been observed on many varieties of fresh produce including climacteric and non-climacteric fruit, tubers, salads and brassicas. The majority of previous studies have used low-intensity (LIUV) UV-C sources. LIUV sources require lengthy treatment times, which are in the region of 6 minutes for tomato fruit. This has, in part, prevented the commercial application of this technique. High-intensity, pulsed polychromatic light (HIPPL) sources, however, have recently been developed. HIPPL sources may have the potential to drastically reduce treatment times and increase their commercial viability. It was shown, here, that the use of HIPPL can control disease (reduce disease progression) caused by Botrytis cinerea and Penicillium expansum and also delay ripening on tomato fruit. Both disease control and delayed ripening were at similar levels for LIUV and HIPPL treatments on mature green fruit. The HIPPL treatments used in these studies can reduce treatment times for tomato fruit by 97.3%. Both HIPPL and LIUV treatments elicit local responses irrespective of the treatment orientation and tomato fruit, therefore, require full surface irradiation. Furthermore, UV-C in the HIPPL source is not required for disease control or delayed ripening. It does, however, contribute approximately 50% towards the total observed effects. Investigations into the mechanisms underpinning postharvest HIPPL and LIUV hormesis, on tomato fruit, identified that the expression of genes involved in plant hormone biosynthesis, defence, secondary metabolism and ripening were affected. This indicates that disease control is achieved through induced resistance. Changes to expression, following treatment, were highly similar for both HIPPL and LIUV treatments and were mediated by salicylic acid, jasmonic acid and ethylene. This may lead to broad range resistance against necrotrophic and biotrophic pathogens as well as abiotic stresses and herbivorous pests. Recently, the exposure of foliage to UV-C has been shown to induce resistance against B. cinerea on Arabidopsis thaliana. The horticultural applications of such treatments, however, have not been explored. Pre-harvest treatments of lettuce in the glasshouse showed variation in damage threshold and optimal treatment to control disease following LIUV and HIPPL treatment. Further sources of variation included the cultivar, pathogen of interest and the point that treatment was applied during the year. Using a controlled environment allowed seasonal variation to be mitigated and both HIPPL and LIUV treatments controlled disease against B. cinerea. For pre-harvest treatments to be a success in the glasshouse, further studies into how both biotic and abiotic factors influence treatment is required. To circumvent the problems associated with pre-harvest treatments and environmental variation in the glasshouse, LIUV seed treatments were performed on tomato. Control of B. cinerea was established with an approximately 10% reduction in incidence and disease progression with a 4 kJ/m2 treatment. When monitoring the effect of treatment on germination and early seedling development it was also identified that an 8 kJ/m2 treatment led to biostimulation of germination and root and shoot growth.

Made available in DSpace on 2016-12-08T16:44:34Z (GMT). No. of bitstreams: 1 PGPV11MA036.pdf: 712032 bytes, checksum: d0c4321bcd64341b4876e7f0b61bd072 (MD5) Previous issue date: 2011-02-02 / The aim of this study was to evaluate xylem functionality, fruit quality and mineral atributes associated with the occurrence of bitter pit in Fuji and Catarina apples. Two experiments were carried out. the first experimente aimed to investigate the relationship between the loss of xylem functionality and calcium deficiency, with the occurrence of bitter pit in Fuji and Catarina apples. Fruits from na orchard in São Joaquim were harvested wekkly until 131 days after full bloom (DAFB) and after this period, frotnightly until comercial harvest (188 DAFB). Fruits were evaluated for fresh weight, functionality of xylem in primary and secondary cortical system (by using a dye infusion technique, with acid fuchsin 1%), mineral analysis (Ca, Mg, K and N) and incidence and severity of bitter pit. The second experimente aimed to ecaluate the postharvest quality of fruits, as well as to identify the best physico-chemical and mineral atributes able to discriminate between fruits with and without bitter pit in 1Fuji1 and 1Catarina1 apples. Fruits were harvested at comercial maturity from na orchard in São Joaquim and then cold stored for four months in refrigerated aira t 1°C and 90-95% RH. After removal from cold storage fruits were assessed in terms of respiration and ethylene production rates, soluble solids contente (SSC), titratable acidity (TA), pH, skin color (hue angle; h°), percentage of skin red color (PSRC), flesh firmness, texture atributes (strength to penetrate the skin and pulp), mineral analysis and incidence and severity of bitter pit. Catarina apples showed a major loss in functionality of the xylem (number of primary and secondary cortical vessels) between 40 and 188 DAFB, resulting in lower intake of calcium to fruit and higher incidence of bitter pit in comparison to Fuji apples. After four months of could storage, Fuji and Catarina apples with bitter pit showed higher respiration and ethylene production rates, higher TA, and low values of flesh firmness, texture atributes, PSRC and pH in comparison to fruit without bitter pit. Regarding the minerals atributes, fruit with the disorder showed lower Ca and higher values for K/Ca, N/Ca, (K+Mg)/Ca and (Mg+K+N)/Ca in the skin and flesh tissues of the distal end of the fruit compared to those without bitter pit. The atributes that best discriminated between fruits with and without bitter pit were the force for flesh penetration and the K/Ca ratio in the pulp in Fuji apples, and TA and the K/Ca ratio in the skin tissue in Catarina apples / O objetivo deste trabalho foi avaliar a funcionalidade do xilema, a qualidade dos frutos e atributos minerais associados à ocorrência de bitter pit em maçãs Fuji&#8223; e Catarina&#8223;. Foram realizados dois experimentos. O primeiro experimento teve como objetivo verificar a relação entre a funcionalidade do xilema e a deficiência de Ca com a ocorrência de bitter pit em maçãs Fuji&#8223; e Catarina&#8223;. Foram utilizados frutos provenientes de um pomar em São Joaquim-SC, colhidos semanalmente até 131 dias após a plena floração (DAPF) e, após este período, quinzenalmente até a colheita comercial (188 DAPF). Os frutos foram avaliados quanto à massa fresca, funcionalidade do xilema no sistema cortical primário e secundário (segundo a técnica de infusão do pedúnculo dos frutos em fucsina ácida a 1%), análise mineral (teores de Ca, Mg, K e N) e incidência e severidade de bitter pit . O segundo experimento teve como objetivo avaliar a qualidade de frutos pós-colheita e identificar os atributos físico-químicos (qualidade) e atributos minerais capazes de discriminar frutos com e sem bitter pit em maçãs Fuji&#8223; e Catarina&#8223;. Foram utilizados frutos provenientes de um pomar em São Joaquim-SC, colhidos na maturação comercial e armazenados por quatro meses em atmosfera do ar a 1°C e UR 90-95%. Após o armazenamento os frutos foram avaliados quanto às taxas respiratória e de produção de etileno, sólidos solúveis (SS), acidez titulável (AT), pH, coloração da epiderme (ângulo hue&#8223;; h°), porcentagem de cor vermelha (PCV), firmeza de polpa, atributos de textura (força para a penetração da casca e da polpa), análise mineral e incidência e severidade de bitter pit . A cultivar Catarina apresentou uma elevada perda na funcionalidade do xilema (número de vasos corticais primários e secundários) no período dos 40 aos 188 DAPF, resultando no menor aporte de Ca aos frutos e maior incidência de bitter pit em comparação à Fuji&#8223;. Após quatro meses de armazenamento refrigerado, maçãs Fuji&#8223; e Catarina&#8223; com bitter pit apresentaram elevadas taxas respiratória e de produção de etileno, alta AT e baixos valores de firmeza de polpa, atributos de textura, PCV e pH, em 7 relação aos frutos sem bitter pit . Quanto aos atributos minerais, frutos com a desordem exibiram menores teores de Ca e elevados valores nas relações K/Ca, N/Ca, (K+Mg)/Ca e (K+Mg+N)/Ca nos tecidos da casca e polpa da região pistilar do fruto, em relação aos frutos sem bitter pit . A força para a penetração da polpa e a relação K/Ca na polpa em maçãs Fuji&#8223;, e a AT e a relação K/Ca na casca em maçãs Catarina&#8223;, foram os atributos que melhor discriminaram frutos com e sem bitter pit

Made available in DSpace on 2016-12-08T16:44:36Z (GMT). No. of bitstreams: 1 PGPV10MA055.pdf: 724635 bytes, checksum: 47f16229cf97fc318aa61ab151a5dad6 (MD5) Previous issue date: 2010-02-05 / The cultivar Catarina produces fruits of good quality, large size and good shape, and is resistant to the main diseases of the apple trees, scab (Venturia inaequalis) and Gala leaf spot (Glomerella cingulata). The commercial use of Catarina apples is limited by its susceptibility to bitter pit, a physiological disorder caused by Ca deficiency in the fruit. This works was carried out to evaluate: 1) the seasonal fluctuation of nutrients in the leaves and fruits of cultivars Catarina, Gala and Fuji, during the vegetative cycle; and 2) the efficiency of sources of Ca, sprayed at preharvest for bitter pit control and the preservation of fruit qualitative attributes of Catarina apples. The researchs were conduced in São Joaquim region, during two growing seasons for evaluation of the nutritional assessment (2004/2005 and 2005/2006), and during three growing seasons for the evaluation of the sources of Ca spraying (from 2004/2005 to 2006/2007). The three cultivars exhibited reductions in the concentration of N, P and K, and increases in the concentration of Ca and Mg in the leaves along the growing season. Among the cultivars, the Catarina had the smallest foliar concentrations of P, Ca and Mg. Catarina apples had the highest increment of fruit mass. Fruits of Catarina , Gala and Fuji showed reduction in the concentration of N, K, Ca and Mg along the growing season. Catarina apples had the highest concentration of K and the smallest concentration of Ca in the fruit. In the cultivars, the Ca content in the fruits increased until the harvest. Catarina had the highest Ca content in the fruit in 2004/2005, and the lowest Ca content in 2005/2006. The low Ca content in the fruit of Catarina incresead the N/Ca, K/Ca, Mg/Ca and (K+Mg)/Ca ratios, especially in 2005/2006, therefore increasing the risk of physiological disorder in the fruit. In the experiment to evaluate the efficiency of sources of Ca sprayed at preharvest, the was no effect of treatments on N, P and K concentrations in the leaves. Only in 2006/2007, preharvest spraying with CalSOL 15 (15 sprayings) increased the Ca concentration in the leaves. In 2004/2005, preharvest spraying with Calboron + CaCl2, Sett, CaCl2, Calboron and S-CaB incresead Ca concentration in the fruit. The control treatment exihibited incidences of bitter pit of 23,9% and 45,5% in 2005/2006 and 2006/2007, respectively. The treatments with Calboron, Sett, Ca Cl2 and Wuxal Cálcio in 2005/2006, and with CaCl2 and CalSOL 15 (10 and 15 sprayings) in 2006/2007, reduced the incidence of bitter pit assessed at harvest. In 2006/2007, the initial severity (at harvest) was not affected by treatments, but the treatments with CaCl2 reduced the severity of this disorder during cold storage. In 2004/2005, 2005/2006 and 2006/2007, the sources of Ca not affect the fruit weight, yield, and flesh firmness, starch index, soluble solids content (SSC), titratable acidity (TA), and SSC/TA ratio of the fruit at harvest / A cultivar Catarina produz frutos de boa qualidade, tamanho grande, bom formato e apresenta resistência às principais doenças da macieira, sarna (Venturia inaequalis) e mancha foliar de Gala (Glomerella cingulata). O plantio comercial da macieira Catarina está limitado pela suscetibilidade ao bitter pit , distúrbio fisiológico relacionado principalmente à deficiência de Ca nos frutos. Os trabalhos tiveram por objetivos avaliar: 1) a variação dos nutrientes nas folhas e nos frutos das cultivares Catarina, Gala e Fuji, durante o ciclo vegetativo, visando diagnosticar as diferenças nutricionais e relacionar com a ocorrência de bitter pit ; e 2) a eficiência de fontes de Ca em pulverização pré-colheita no controle de bitter pit e na preservação dos atributos qualitativos dos frutos da cultivar Catarina. Os trabalhos foram conduzidos na região de São Joaquim, SC, durante as safras 2004/2005 e 2005/2006 para o monitoramento nutricional, e durante as safras 2004/2005 a 2006/2007 para a avaliação das fontes de Ca. As três cultivares apresentaram reduções nos teores de N, P e K, e aumento nos teores de Ca e Mg nas folhas ao longo do ciclo vegetativo. A cultivar Catarina apresentou os menores teores de P, Ca e Mg nas folhas. Entre as cultivares, a cultivar Catarina apresentou a maior massa final dos frutos. As cultivares apresentaram reduções nos teores de N, K, Ca e Mg nos frutos ao longo do ciclo vegetativo. Os frutos da cultivar Catarina apresentou o maior teor de K e o menor teor de Ca em relação às cultivares Gala e Fuji. O conteúdo de Ca nos frutos aumentou até a colheita nas três cultivares. Na safra 2004/2005, a cultivar Catarina apresentou o maior conteúdo de Ca nos frutos, mas na safra 2005/2006, apresentou o menor conteúdo de Ca. O baixo teor de Ca nos frutos da cultivar Catarina aumentou o valor das relações N/Ca, K/Ca, Mg/Ca e (K+Mg)/Ca, principalmente na safra 2005/2006, aumentando a probabilidade da ocorrência de distúrbios fisiológicos nos frutos. No experimento de pulverização pré-colheita com fontes de Ca, não foi verificado efeito nos teores de N, P e K nas folhas. Das três safras, apenas na safra 2006/2007, o teor de Ca nas folhas aumentou com o tratamento CalSOL 15 (15 aplicações). Na safra 2004/2005, o teor de Ca nos frutos aumentou com os tratamentos Calboron + CaCl2, Sett, CaCl2, Calboron e S-CaB. Na testemunha, o bitter pit ocorreu em 23,9% e 45,5% dos frutos, nas safras 2005/2006 e 2006/2007, respectivamente. Os tratamentos Calboron, Sett, CaCl2 e Wuxal Cálcio (safra 2005/2006) e os tratamentos CaCl2 e CalSOL 15 (10 e 15 aplicações) (safra 2006/2007) reduziram a incidência de bitter pit avaliado na colheita. Na safra 2006/2007, a severidade inicial (logo após a colheita) de bitter pit não foi afetada pelos tratamentos, mas o tratamento CaCl2 reduziu a severidade final dos frutos armazenados. Nas safras 2004/2005, 2005/2006 e 2006/2007, as fontes de Ca não afetaram o peso médio, o rendimento de frutos, a firmeza da polpa, o índice de iodo-amido, o teor de sólidos solúveis (SS), a acidez titulável (AT) e relação SS/AT na colheita