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The objective of this study was to evaluate the application of hot water treatment to tomato fruits (Solanum lycopersicum cv. TA234) genetically modified with silencing of the TomloxB gene. Unmodified and genetically modified tomato fruits were immersed in water at 40°C for 10, 20 and 30 seconds. Subsequently, fruits were stored at 25°C for 18 days. Physiology was assessed and electrolyte leakage, lipoxygenase and polygalacturonase activities were monitored. Treatment applied to the genetically modified tomatoes at 40°C for 30 seconds, resulted in slower ripening, decreased metabolic activity and maintained the attributes in optimal conditions for longer time, increased the postharvest life of the genetically modified tomatoes until 18 days. Lipoxygenase and polygalacturonase activities were partially inhibited.

Green-ripe banana fruit are sensitive to chilling injury (CI) and, thus, prone to postharvest quality losses. Early detection of CI facilitates quality maintenance and extends shelf life. CI affects all metabolic levels, with membranes and, consequently, photosynthesis being primary targets. Optical techniques such as chlorophyll a fluorescence analysis (CFA) and spectroscopy are promising tools to evaluate CI effects in photosynthetically active produce. Results obtained on bananas are, however, largely equivocal. This results from the lack of a rigorous evaluation of chilling impacts on the various aspects of photosynthesis. Continuous and modulated CFA and imaging (CFI), and VIS remission spectroscopy (VRS) were concomitantly applied to noninvasively and comprehensively monitor photosynthetically relevant effects of low temperatures (5 °C, 10 °C, 11.5 °C and 13 °C). Detailed analyses of chilling-related variations in photosynthetic activity and photoprotection, and in contents of relevant pigments in green-ripe bananas, helped to better understand the physiological changes occurring during CI, highlighting that distinct CFA and VRS parameters comprehensively reflect various effects of chilling on fruit photosynthesis. They revealed why not all CFA parameters can be applied meaningfully for early detection of chilling effects. This study provides relevant requisites for improving CI monitoring and prediction.

‘Honeycrisp’ (Malus domestica Borkh), a premium apple cultivar, is prone to preharvest fruit drop (PFD), bitter pit (BP) and decline in quality during long-term storage. To enhance the fruit retention and storage quality in ‘Honeycrisp’, an aqueous composition containing hexanal was applied as a preharvest spray. Hexanal treated trees retained 18% more fruit compared to control trees. Fruit firmness was significantly improved by hexanal while fresh weight, and total soluble solids (TSS) did not vary in response to the treatment at the field. Abscisic acid (ABA) in the fruit abscission zone (FAZ) was substantially reduced by hexanal at commercial maturity. At this stage, a total of 726 differentially expressed genes (DEGs) were identified between treated and control FAZ. Functional classification of the DEGs showed that hexanal downregulated ethylene biosynthesis genes (SAM2, ACO3, ACO4,and ACO4-like),while it upregulated the receptor genes (ETR2 and ERS1). Genes related to ABA biosynthesis (FDPS and CLE25) and signaling were also downregulated. Further, hexanal downregulated the expression of genes related to cell wall degrading enzymes, including polygalacturonase, glucanase, and expansin. These findings revealed that hexanal reduced the sensitivity of FAZ cells to ethylene and ABA. Simultaneously, hexanal reduced the cell wall degradation of FAZ cells by regulating genes involved in cell wall modifications. Thus, delayed fruit abscission by hexanal in ‘Honeycrisp’ is most likely achieved by minimizing ABA through an ethylene-dependent mechanism. Further investigation of effects of hexanal on long-term storage quality in ‘Honeycrisp’ revealed that treated apples had higher TSS under both cold and cold followed by room temperature storages. In addition, treated apples had lower incidence, and progression of BP, lower phospholipase D (PLD) enzyme activity and decreased expression of MdPLDα1, MdPLDα4, MdCaM2, MdCaM4 and MdCML18 genes. Therefore, improved postharvest quality, including the lower incidence of BP in hexanal treated ‘Honeycrisp’ apples may be associated with lower membrane damage due to downregulation of PLD. Thus, hexanal application promises to be a great technology to control fruit drop, reduce bitter pit, enhance fruit qualities, and marketability in ‘Honeycrisp’ apples, given that this cultivar is categorized as susceptible to fruit drop and bitter pit. Global Affairs Canada through their Canadian International Food Security Fund (CIFSRF) ; Arrell scholarship by the Arrell Food Institute at the University of Guelph

Green-ripe banana fruit are sensitive to chilling injury (CI) and, thus, prone to postharvest quality losses. Early detection of CI facilitates quality maintenance and extends shelf life. CI affects all metabolic levels, with membranes and, consequently, photosynthesis being primary targets. Optical techniques such as chlorophyll a fluorescence analysis (CFA) and spectroscopy are promising tools to evaluate CI effects in photosynthetically active produce. Results obtained on bananas are, however, largely equivocal. This results from the lack of a rigorous evaluation of chilling impacts on the various aspects of photosynthesis. Continuous and modulated CFA and imaging (CFI), and VIS remission spectroscopy (VRS) were concomitantly applied to noninvasively and comprehensively monitor photosynthetically relevant effects of low temperatures (5 °C, 10 °C, 11.5 °C and 13 °C). Detailed analyses of chilling-related variations in photosynthetic activity and photoprotection, and in contents of relevant pigments in green-ripe bananas, helped to better understand the physiological changes occurring during CI, highlighting that distinct CFA and VRS parameters comprehensively reflect various effects of chilling on fruit photosynthesis. They revealed why not all CFA parameters can be applied meaningfully for early detection of chilling effects. This study provides relevant requisites for improving CI monitoring and prediction.

For fresh-cut salad production, hot-water treatment (HWT) needs optimization in terms of temperature and duration to guarantee a gentle and non-stressing processing to fully retain product quality besides an effective sanitation. One major initial target of heat treatment is photosynthesis, making it a suitable and sensitive marker for HWT effects. Chlorophyll fluorescence imaging (CFI) is a rapid and non-invasive tool to evaluate respective plant responses. Following practical applications in fruit salad production, apples of colored and of green-ripe cultivars (&lsquo, Braeburn&rsquo, &lsquo, Fuji&rsquo, Greenstar&rsquo, Granny Smith&rsquo, ), obtained from a local fruit salad producer, were hot-water treated from 44 to 70 &deg, C for 30 to 300 s. One day after HWT and after 7 days of storage at 4 &deg, C, CFI and remission spectroscopy were applied to evaluating temperature effects on photosynthetic activity, on contents of fruit pigments (chlorophylls, anthocyanins), and on various relevant quality parameters of intact apples. In &lsquo, apples, short-term HWT at 55 &deg, C for 30 to 120 s avoided any heat injuries and quality losses. The samples of the other three cultivars turned out to be less sensitive and may be short-term heat-treated at temperatures of up to 60 &deg, C for the same time. CFI proved to be a rapid, sensitive, and effective tool for process optimization of apples, closely reflecting the cultivar- or batch-specificity of heat effects on produce photosynthesis.

The Mediterranean fruit fly (Ceratitis capitata Wiedemann) is a worldwide pest of economi importance because attacks a large number of agricultural crops and for the extent of the damage it causes. Among the alternative control strategies to the use of sprays with synthetic insecticides, a very important role can be played by powders obtained from rocks whose activity arise from the ability to form a film of white powder, which acts as a repellent and irritant to insects. This film can also interfere with plants’ physiology and affect quality of fruit. In this study the efficacy of a commercial kaolin-based formulation to control medfly infestations was compared to synthetic insecticides commonly used against this pest (phosmet, alfa-cypermethrin, deltamethrin). The results showed a significant reduction of medfly attacks in fruits treated with insecticides (1.5% damaged fruit) or with kaolin (0.5% damaged fruits) compared to the untreated sample (10% damaged fruits), while physiological and quality parameters ded not show relevant differences between treatments and control fruit. Overall results highlight how the use of kaolin represents a valid alternative to treatments with synthetic insecticides to control C. Capitata attacks on peaches, while not affecting fruits’ quality., Advances in Horticultural Science, Vol. 34 No. 1S (2020): Special issue on postharvest

&lsquo, Fuji&rsquo, is among the most cultivated apples worldwide but affected by the disorder bitter pit (BP). Calcium deficiency plays an important role on fruit susceptibility to BP. The objectives of this study were to determine nutritional relationships in BP-affected fruit and to verify if Vis-NIR models can predict Ca concentration in &lsquo, apples. Fruit was harvested during 2018 season from two different orchards with historical high BP incidence. Seven hundred and fifty apples were stored at 0 &deg, C for 150 days plus 10 days at 20 &deg, C for BP assessments. After storage, 20 fruit with BP symptoms (BP+) and 20 healthy fruit (BP&minus, ) were assessed individually for mineral concentration. Vis-NIR evaluation involved a spectra range from 285 to 1200 nm to predict Ca concentration from &lsquo, powder enriched Ca solutions. In each orchard, healthy apples had significantly higher Ca concentration than apples with BP. The K/Ca and Mg/Ca ratios were significantly lower in healthy fruit compared with BP&minus, affected fruit. The relationship B/Ca proved to be significant in BP fruit. Although Ca interaction with organic substances and/or cellular structures could influence NIR spectra in fresh fruit, our results showed that Vis-NIR models could not be used to direct prediction of fruit Ca concentration.

[EN] Background: Zucchini fruit is susceptible to chilling injury (CI), but the response to low storage temperature is cultivar dependent. Previous reports about the response of zucchini fruit to chilling storage have been focused on the physiology and biochemistry of this process, with little information about the molecular mechanisms underlying it. In this work, we present a comprehensive analysis of transcriptomic changes that take place after cold storage in zucchini fruit of two commercial cultivars with contrasting response to chilling stress. Results: RNA-Seq analysis was conducted in exocarp of fruit at harvest and after 14 days of storage at 4 and 20 degrees C. Differential expressed genes (DEGs) were obtained comparing fruit stored at 4 degrees C with their control at 20 degrees C, and then specific and common up and down-regulated DEGs of each cultivar were identified. Functional analysis of these DEGs identified similarities between the response of zucchini fruit to low temperature and other stresses, with an important number of GO terms related to biotic and abiotic stresses overrepresented in both cultivars. This study also revealed several molecular mechanisms that could be related to chilling tolerance, since they were up-regulated in cv. Natura (CI tolerant) or down-regulated in cv. Sinatra (CI sensitive). These mechanisms were mainly those related to carbohydrate and energy metabolism, transcription, signal transduction, and protein transport and degradation. Among DEGs belonging to these pathways, we selected candidate genes that could regulate or promote chilling tolerance in zucchini fruit including the transcription factors MYB76-like, ZAT10-like, DELLA protein GAIP, and AP2/ERF domain-containing protein. Conclusions: This study provides a broader understanding of the important mechanisms and processes related to coping with low temperature stress in zucchini fruit and allowed the identification of some candidate genes that may be involved in the acquisition of chilling tolerance in this crop. These genes will be the basis of future studies aimed to identify markers involved in cold tolerance and aid in zucchini breeding programs., This research has been funded by the Ministerio de Economia y Competitividad and Fondo Europeo de Desarrollo Regional FEDER (Project AGL2014-54598-C2).

Sweet cherry fruits (Prunus avium cvs. 'Canada Giant', 'Ferrovia') were harvested at commercial maturity stage and analyzed at harvest and after maintenance at room temperature (storage at ∼20°C, shelf life) for 1, 2, 4, 6, and 8 days, respectively. Fruit were initially analyzed for respiration rate, qualitative attributes and textural properties: 'Canada Giant' fruit were characterized by higher weight losses and stem browning index, being more intense over the late stages of shelf life period; meanwhile 'Ferrovia' possessed appreciably better performance even after extended shelf life period. A gradual decrease of respiration rate was monitored in both cultivars, culminated after 8 days at 20°C. The sweet cherry fruit nutraceutical profile was monitored using an array of instrumental techniques (spectrophotometric assays, HPLC, (1)H-NMR). Fruit antioxidant capacity was enhanced with the progress of shelf life period, concomitant with the increased levels of total anthocyanin and of phenolic compounds. 'Ferrovia' fruit presented higher contents of neochlorogenic acid and p-coumaroylquinic acid throughout the shelf life period. We further developed an (1)H-NMR method that allows the study of primary and secondary metabolites in a single running, without previous separation and isolation procedures. Diagnostic peaks were located in the aliphatic region for sugars and organic acids, in the aromatic region for phenolic compounds and at 8.2-8.6 ppm for anthocyanins. This NMR-based methodology provides a unifying tool for quantitative and qualitative characterization of metabolite changes of sweet cherry fruits; it is also expected to be further exploited for monitoring temporal changes in other fleshy fruits.

The physiological responses of fruits and vegetables toransit conditions such as vibration, temperature, humidity and air composition were investigated as a basic problem of postharvest handling of horticultural crops. Temperature: The respiratorry metabolism of some fruits and vegetables was disturbed by rapid change of ambient temperature exceeding the range of 20℃. Quality deterioration of some vegetables under fluctuating temperatures was rapid compared to those held under constant temperature. These effects of temperature on the physiology and keeping quality of horticultural crops were different depending on the kind of commodity and its developmental stage. Air composition: Critical O2 concentration estimated by extinction point, the lowest O2 level at which the respiratory quotient remains at 1.0, was different for the various horticultural crops. The respiratory responses of fruits and vegetables to high CO2 were different and depended on the kind of commodity and its developmental stage. In non-climacterric fruits and several vegetables, in which ethlene evolution was not detected, high CO2 had litter or no effect at all on respiration. In some vegetables such as cucumber and lettuce treated with high CO2, ethylene evolution was induced during or after treatment and them respiration increased. These results indicate that the respiratory response of fruits and vegetables to high CO2 might be mediated through the effects of CO2 on ethlene synthesis and/ or action. Humidity: The respiratory responses of horticultural crops to relative humidity seemed to be classified into three groups; accelerative, inhibitive and insensitive at low humidity. In climacteric fruit such as bananas, ripening was accelerated under low humidity. Softening was observed in some fruits and vegetables nuder low humidity. The induction of softening seemed to be independent of endogenous ethylene concentration. These results may indicate that polygalacturonase activity is induced and then degradation of cell wall polysaccharides is initiated by water deficit stress under low humidity. Vibration: Some fruits and vegetables were physiologically sensitive to artificial vibrating conditions which were not sufficient to produce direct injury. Through intensive vibration, some metabolic pathways were suppressed while others were activated. AS a result, intensive vibration above the critical point for every fruit and vegetable caused quality deterioration. Based on the above observations, improvement of postharvest handling techniques of horticultural crops are discussed from a physiological point of view., 園芸生産物の流通工程が時間的・距離的に長くなるに従って、この間での管理が品質保持の上で重要な課題になってくる。本研究は、主として輸送工程に焦点を絞りながら、技術改善の基礎資料を得ることを目標として実施されたものである。まず、現実の輸送環境の実態調査を行い、問題点の指摘を行った上で、それらに基づいてシミュレーション研究を実施し、振動、温度、湿度及び空気組成環境ごとに生産物の生理的反応を再整理して、技術改善の方向性について生理学的見地から論じようとした。温度:較差20℃にも及ぶような急激な温度変動は生理的にみて好ましくないこと、小さな周期的変動も定温に比べて鮮度低下が大きいことを明らかにした上、いずれも種類によって耐性が異なることを示唆した。空気組成:呼吸商1を維持する最小酸素濃度である消滅点からみた酸素濃度の限界点は種類によって異なった。高炭酸ガスと呼吸活性との関係をみると、種類によって抑制されるもの、変化がないもの、逆に促進されるものがあり、抑制されるものはエチレン生成の抑制を伴っていることが明らかとなった。このことから、高炭酸ガスの鮮度保持効果は、直接的に呼吸活性を抑制するのではなく、エチレン生成の抑制を介してあらわれるものと思われた。温度:低湿に伴う萎れによって、種類によって呼吸活性が抑制される場合、変化がない場合、促進される場合があった。クライマリテリック型果実では低湿で成熟促進がみられた。急激な萎れによってエチレン生成が誘導された。さらに、萎れによって肉質軟化が促進され、これはエチレン生成とは無関係に萎れストレスによって直接PG活性が誘導されることが一因であることを示唆した。振動:振動によって呼吸活性の増大がみられた。振動刺激が一定強度以上になると生理的に変調が誘発され、ひいては食味低下に連なることを示した。以上の成果に基づいて、主として生理的側面から輸送工程を含めて流通技術改善の方向について論じた。

Inadequate temperatures during the shipping and commercialization of cut tropical flowers may accelerate the senescence process and cause chilling injury, leading to symptoms that have not yet been described for Heliconia bihai . The aim of the present study was to evaluate physiological responses in cut inflorescences of H. bihai cv. Lobster Claw (LC) and cv. Halloween (HW) as well as symptoms of senescence and chilling injury. For such, changes in fresh weight, bract color ( L *, a * and b *), percentage of absolute integrity (PAI) of cell membranes and leakage of potassium ions (LPI) were determined. The flowering stems were evaluated at five different intervals after harvest (0, 2, 4, 6 and 8 d). A refrigerated treatment (RT) with a temperature of 6.5 °C and 85% relative humidity was compared to a control treatment (CT) at room temperature of 24 °C and 66% relative humidity. Both cultivars stored at 6.5 °C exhibited dryness of bract tissue (symptom of senescence) and dark stains that became brownish and evolved to necrosis (symptom of chilling injury). The visual quality of inflorescences decreased with time in both cultivars maintained without refrigeration. The severity of chilling injury increased with the length of storage time in both cultivars. There was a significant reduction in the fresh weight of inflorescences in both treatments (RT and CT) and both cultivars (LC and HW). Bract color changed in both cultivars at 6.5 °C. There was no change in PAI throughout the evaluation period in the inflorescences stored at room temperature, whereas those stored at 6.5 °C for 6 and 8 d had lower PAI values. The inflorescences in the control treatment underwent no change in LPI values, whereas those stored under refrigeration had increased LPI values after the sixth day of storage. The physiological responses of cut Heliconia flowers were influenced by storage period and temperature, as demonstrated by visual symptoms of chilling injury and senescence.

The specific objectives of this study were to evaluate the effect of storage duration on the survival rate of rooted cuttings and to determine the rooting and survival rates of non-rooted cuttings for two standard carnation cultivars (that is., Dianora and Vittorio). The survival rates of rooted cuttings showed differences depending on the cultivar tested. Specifically, the Vittorio cultivar had a better reaction to long-term storage. The survival and rooting rates of non-rooted cuttings after cold storage also showed differences depending on the cultivar tested. Vittorio cultivar reacted better to storage than the Dianora cultivar.

Tomato (Lycopersicon esculentum Mill.) is an important commercial crop. High quality tomatoes for the local and export markets are grown hydroponically. In this study, the effect of electrically activated sodium bicarbonate and non-ionized sodium bicarbonate solutions on productivity and postharvest quality of hydroponically grown tomatoes was tested. Sodium bicarbonate is a ready source of bicarbonate. By using a novel technique obtained from Radical Waters (Pty) Ltd., ionized bicarbonate (anolyte) can be produced from sodium bicarbonate and applied to plants to stimulate photosynthesis, and improve yield and postharvest quality. The effect of ionized and non-ionized bicarbonate solutions on productivity and postharvest quality was studied by measuring the following: (1) Preharvest growth rate (leaf length, stem height and diameter); total yield; starch concentration in leaves; fruit count; leaf chlorophyll content; CO2-uptake; soluble solids and concentration of K+, Na+ and NO3¯ in leaves. (2) Postharvest rate of respiration and transpiration; ethylene production; total soluble solids content; ascorbic acid content; pH; fruit firmness; fruit mass; fruit diameter; longevity; concentration of K+, Na+ and NO3¯ at one-third towards maturity, two-thirds towards maturity, at maturity and during ripening, and rate of ripening at 12 and 23°C. During the preharvest period, plants treated with anolyte showed increased growth rate, starch concentration, chlorophyll content, soluble solids content and improved yield. During the growth period, the concentration of K+ and NO3¯ was higher in plants treated with anolyte than in plants treated with non-ionized sodium bicarbonate. The concentration of Na+ during the preharvest period was higher in plants treated with non-ionized sodium bicarbonate than in plants treated with anolyte. After harvest, fruits from plants treated with anolyte had a reduced rate of ethylene production, rate of respiration and transpiration, total increased soluble solids and ascorbic acid content than fruits from plants treated with non-ionized sodium bicarbonate. Fruits from plants treated with anolyte had reduced rate of ripening and were larger and heavier than fruits from plants treated with non-ionized sodium bicarbonate. Anatomical and ultrastructural studies revealed that treatment with anolyte stimulated cell growth and photosynthesis. These results were confirmed by comparing the CO2-uptake of treated and untreated plants. Application of anolyte stimulated photosynthesis, thus improving yield and fruit quality. Treatment with non-ionized sodium bicarbonate resulted in salt- stress and calcium deficiency. Some of the fruits on plants treated with non-ionized sodium bicarbonate suffered from blossom-end rot due to salt-stress. Prof. C.S. Whitehead

International audience; This chapter focuses on the origin, description, and control of bacterial and fungal spoilage of fruits and vegetables. It talks about some chemical treatments like fungicides and decontamination for fruits and vegetables. Synthetic antimicrobial chemicals are still widely applied to fruits and vegetables after harvest, and decontamination aims at reducing the number of microbial contaminants on the surface of fruits and vegetables, thereby prolonging the time required to develop spoilage. Spoilage of fruits and vegetables is the result of complex interactions between a living plant organ and its microflora, and therefore deals with plant pathology and plant physiology as much as with food microbiology. Control of postharvest spoilage microorganisms largely accounts for these interactions, which could be additionally affected by the global climate change. Today, millions of tons of fruits and vegetables cross seas, oceans, and continents, from the Southern to the Northern hemisphere and from tropical to temperate zones. Developing countries increasingly play a role in this world market. Further development of minimally processed fruits and vegetables will bring new questions as to how to maintain the quality of processed produce, which requires prevention of spoilage, when the produce is often heavily stressed and naturally occurring defenses of the intact tissues have been overwhelmed. Consumer demand for high-quality fruits and vegetables produced under environmentally friendly conditions will probably not decrease. Finding solutions to historical problems associated with the preservation of fruits and vegetables against infection and spoilage by bacteria and fungi will be an ongoing future challenge.

At present, the value and production quantity of mango fruits are increasing worldwide. Many studies emphasize how chilling injury phenomena affect the quality of tropical fruits, such as mango, during postharvest handling, transport, and storage. Since mango is one of the most favored and popular fruits in the world market, and is considered to be a climacteric fruit, ripening rapidly after harvest, it is essential to study how storage affects the external and internal fruit quality in order to extend the shelf life. Chilling injury occurs when mango thereafter, are exposed to temperatures below 15 o C, but above the freezing point of the tissue. After a certain period of storage at these temperatures, and especially after a subsequent rise in temperatures, certain injuries in the plant tissue can be seen, such as water soaking, pitting, or browning. The possible causes of this type of injury will be reviewed and the consequences for cell components summarized. A distinction is made between the primary processes of chilling injury and subsequent secondary injuries. The membrane phase change and oxidative stress models of primary chilling injury are introduced. How cell components are affected by chilling injury is then discussed, as is the relationship between pre-harvest conditions, post-harvest handling, and injury. Lastly, the roles of different anti-oxidants and anti-oxidant enzymes are discussed and some techniques used for the measurement of chilling injury are introduced.

At present, the value and production quantity of mango fruits are increasing worldwide. Many studies emphasize how chilling injury phenomena affect the quality of tropical fruits, such as mango, during postharvest handling, transport, and storage. Since mango is one of the most favored and popular fruits in the world market, and is considered to be a climacteric fruit, ripening rapidly after harvest, it is essential to study how storage affects the external and internal fruit quality in order to extend the shelf life. Chilling injury occurs when mango thereafter, are exposed to temperatures below 15 o C, but above the freezing point of the tissue. After a certain period of storage at these temperatures, and especially after a subsequent rise in temperatures, certain injuries in the plant tissue can be seen, such as water soaking, pitting, or browning. The possible causes of this type of injury will be reviewed and the consequences for cell components summarized. A distinction is made between the primary processes of chilling injury and subsequent secondary injuries. The membrane phase change and oxidative stress models of primary chilling injury are introduced. How cell components are affected by chilling injury is then discussed, as is the relationship between pre-harvest conditions, post-harvest handling, and injury. Lastly, the roles of different anti-oxidants and anti-oxidant enzymes are discussed and some techniques used for the measurement of chilling injury are introduced.

This thesis deals with the analysis of postharvest physiological deterioration (PPD) in cassava tuberous roots at the physiological, biochemical and molecular level. By setting up a uniform visual system to monitor the onset and maintenance of PPD under the experimental conditions, amongst others physico-chemical properties of starch were characterized. Furthermore using this system, around 6,000 TDFs (transcript derived fragments) were screened via 100 primer combinations using cDNA-AFLP. 70 TDFs showing an up-regulated, a down regulated or a transiently expression pattern were isolated following the first 72 hours of PPD. Based on the sequence information, a functional catalogue of these TDFs was established. By concentrating on enzymes possibly involved in oxidative stress, biochemical results indicated that PPD may be a peroxidase-mediated process. Using a reverse genetics approach, the putative cassava dad1 (defender against cell death gene 1) homologue was transformed into cassava FEC (friable embryogenic callus) lines. Transgenic plants were produced and characterized.

This thesis deals with the analysis of postharvest physiological deterioration (PPD) in cassava tuberous roots at the physiological, biochemical and molecular level. By setting up a uniform visual system to monitor the onset and maintenance of PPD under the experimental conditions, amongst others physico-chemical properties of starch were characterized. Furthermore using this system, around 6,000 TDFs (transcript derived fragments) were screened via 100 primer combinations using cDNA-AFLP. 70 TDFs showing an up-regulated, a down regulated or a transiently expression pattern were isolated following the first 72 hours of PPD. Based on the sequence information, a functional catalogue of these TDFs was established. By concentrating on enzymes possibly involved in oxidative stress, biochemical results indicated that PPD may be a peroxidase-mediated process. Using a reverse genetics approach, the putative cassava dad1 (defender against cell death gene 1) homologue was transformed into cassava FEC (friable embryogenic callus) lines. Transgenic plants were produced and characterized.

In The Netherlands Lilium is economically the fourth overall flower crop for cut flower production. Longevity is a main quality characteristic for cut flowers. During postharvest handling of Asiatic hybrid lilies pretreatment with chemical solutions containing silver is carried out to ensure a satisfactory longevity at the consumers'. However, the extent to which such a treatment can delay senescence is limited and is dependent on the genotype. Developing cultivars with genetically improved longevity may provide the consumer with a more reliable expectation for postharvest quality in a less environment polluting way. Flower longevity is a particularly difficult genetic characteristic to assess, since it is markedly affected by growing conditions prior to harvest, stage of flowering at harvest and environmental conditions during distribution and after sale. Additionally, longevity of lily is complex because of its inflorescence-type flower. Longevity is determined by two conflicting processes: (1) promotion of flower bud growth and anthesis; (2) retardation of metabolic processes leading to senescence. Therefore, besides knowledge of genetic aspects of flower longevity also insight in the physiological regulation is needed for its improvement. The objectives of the experiments described in this thesis were to obtain knowledge of (1) methods for longevity determination, (2) available genotypic variation, (3) mode of inheritance and (4) physiological regulation of postharvest flower longevity in Asiatic hybrid lilies.The development of a standardized method for the determination of flower longevity in lily is described. To optimize the screening procedure, the main sources of environmental variance (parameter for screening, harvest stage) were located and standardized, whereas conditions improving the degree of variation among genotypes (evaluation temperature) were determined and optimized (Chapter 2 and 3). By using standardized conditions during forcing, harvest and postharvest evaluation measurements became discriminative and repeatable. Standardization of the forcing method is usually not possible in practice. The ranking of the genotypes based on their longevity levels using standardized conditions during forcing was comparable with the ranking found when forcing conditions in practice were used (Chapter 4). This makes screening results highly reliable for practical use. Because of the large influence of temperature on flower longevity postharvest evaluation should preferably be carried out under controlled temperature conditions.For breeding purposes adequate genotypic variation in the breeding material is necessary. Large differences in individual flower longevity were found screening a wide range of genetic material of Asiatic hybrid origin (Chapter 4). Interspecific hybridization research showed that crosses between genotypes from different taxonomic sections is possible (Chapter 1 and 8). So, enhancement of the exploitable genetic variation may be obtained by screening also other lily groups. The in potential reachable individual flower longevity, not preceded by stress, appeared to be a reliable overall parameter for screening as postharvest stress conditions (storage, ethylene) introduced no large differences in the ranking of the genotypes based on their longevity levels (Chapter 8).Segregation after crossbreeding makes selection possible. Large variation in flower longevity within and among progenies was found. Selection at seedling level appeared to be possible because of a high broad-sense heritability based on one individual plant per genotype and because of an equal expression of individual flower longevity in plants obtained from both seedling bulbs and scale propagated bulbs (Chapter 5). This can considerably speed up the breeding process.For an efficient selection of genotypes with improved flower longevity, knowledge is required of the inheritance of flower longevity. Genetic analysis of the results of the individual plant test showed that additive genetic variance is important in the inheritance of individual flower longevity as the general combining ability (GCA) was the most important genetic component and the estimate for narrow- sense heritability was high. Consequently, individual flower longevity of the genotype can be used as an indication for its breeding value in practical breeding (Chapter 5). A more specific statement on the inheritance of flower longevity can be obtained by indirect selection using genetic markers as discussed in Chapter 8.The physiological regulation of postharvest longevity was investigated by studying the role of tepal carbohydrate content (Chapter 6 and 7). The importance of tepal carbohydrate content and distribution in lily postharvest performance (bud-growth, anthesis, longevity) was revealed by comparing the development of inflorescence-attached and detached buds and flowers. Genotypic differences in the availability and use of carbohydrate were found. Per genotype tepal carbohydrate and individual flower longevity of detached flowers were well correlated. Blocking carbohydrate export by detaching the flowers from the inflorescence increased their longevity compared to the longevity of inflorescence-attached flowers. The complexity of the carbohydrate economy within lily inflorescences hampered the detection of a causal relationship among genotypes. However, the data presented suggest that genotypic differences in flower longevity might at least partially be due to genotypic differences in postharvest carbohydrate utilization (Chapter 7).In conclusion, the prospects for improving flower longevity in lily by breeding and selection are promising. The methods described for screening and selection, the genotypic variation in flower longevity found in this study and the way of inheritance as discussed in Chapter 5 make it possible to obtain new lily cultivars with an improved flower longevity in a relatively short period of time. Furthermore, a high broad-sense heritability in combination with a large segregation of individual flower longevity are of great benefit in linkage studies and future breeding programs based on indirect selection using genetic markers. The physiological regulation of lily flower longevity and the important but partially unknown role of carbohydrates in this complex process needs still further research.

Nuclear Magnetic Resonance Imaging experiments have been performed on cherimoya fruit to provide an image contrast dependent on changes in water status. Since those changes are concomitant to ripening we have assayed their relationship to physical destructive measurements conventionally used as ripening parameters. Relaxation times (T1 and T2) were found to increase sharply at the beginning of the monitoring period, and more slowly afterwards. Firmness evolution was found to be similar. Regression analysis proved a good correlation between both measurements. Results support the suitability of MRI as an accurate monitoring tool, both for basic research and for practical applications.