Vegetable grafting confers soil-borne disease resistance through the use of selected rootstocks. Additional costs associated with grafted vegetable seedling propagation limit grower access to this technology. The use of low temperature storage in grafted seedling production reduces labor costs and allows propagators to meet the seasonal and narrow-window demand of growers. For the first part of the experiment 22 genotypes of Solanaceae or Cucurbitaceae seedlings were evaluated in low temperature storage conditions (5 or 12°C). Seedling performance was better in 12°C storage than in 5°C storage. For the second part of the experiment watermelon, the most low-temperature sensitive species found in our first study, was grafted onto two different commercial rootstocks or on to other watermelon seedlings and stored at 12°C for two and four weeks. Both 'Strong Tosa' and 'Emphasis' rootstocks conferred chilling tolerance during storage to watermelon scions, allowing storage of grafted plants for two weeks.

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.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-10-17T19:51:05Z No. of bitstreams: 1 ALESSANDRA ALMEIDA CASTRO - TESE PPGEP 2004..pdf: 50999854 bytes, checksum: 5c3c28a3bdfe146c8c95c174dbbd858e (MD5) / Made available in DSpace on 2018-10-17T19:51:05Z (GMT). No. of bitstreams: 1 ALESSANDRA ALMEIDA CASTRO - TESE PPGEP 2004..pdf: 50999854 bytes, checksum: 5c3c28a3bdfe146c8c95c174dbbd858e (MD5) Previous issue date: 2004-08-20 / Capes / O objetivo desta pesquisa foi estudar o efeito das técnicas de: a) congelamento nas temperaturas de -20 °C, -196 °C e -170 °C; b) armazenamento as temperaturas de (-20 °C, -30 °C e -170 °C, e c) do método de descongelamento (temperatura ambiente: aproximadamente 25 °C e em banho termostatizado: 35 °C) sobre duas amostras de camarão: 1) com exoesqueleto e cabeça e 2) sem exoesqueleto e sem cabeça, por um período de 12 meses de armazenamento. Foram determinados os seguintes parâmetros: a) características físicas (massa, comprimento, espessura e volume); b) cinética de congelamento as temperaturas de -20 °C, -170 °C e -196 °C; c) propriedades termofisicas (densidade, calor específico, difusividade térmica e condutividade térmica); d) características físico-químicas (conteúdo de água, cinzas, proteínas, pH, carboidratos, gorduras, calorias, exsudado e um atributo de textura: dureza); e) caracterização microbiológica (salmonela, coliformes fecais, vibrio parahaemolyticus) e f) avaliação sensorial (sabor, odor, textura e aparência), visando verificar a eficácia das técnicas de congelamento e descongelamento na qualidade do camarão armazenado. Na análise da cinética, as curvas de congelamento obtidas à temperatura de -20 °C para o camarão com exoesqueleto e cabeça e para o filé foram observadas claramente as três fases, ou seja, resfriamento, cristalização e pós-congelamento. Este fato também ocorreu para o camarão com cabeça congelado a -170 °C, já para o filé congelado a -170 °C não se distinguiu com clareza a fase I da Fase II, ou seja, a fase de resfriamento e a fase de cristalização, fato este atribuído a maior velocidade de congelamento. Nas curvas de congelamento do camarão com cabeça e filé quando estes foram submetidos ao congelamento por imersão em N2 líquido (-196 °C) também não se observou uma distinção entre as fases de resfriamento e cristalização. Com relação às propriedades termofisicas, a densidade do camarão "fresco" (25 °C) com exoesqueleto e cabeça foi de l,066g/cm3 e do filé foi de l,02g/cm3. Os valores médios do calor específico do camarão com exoesqueleto e do filé "fresco" foram de 0,84 e 0,86 kcal/kg °C, respectivamente e para o camarão com exoesqueleto e filé à temperatura de -170 °C foram de 0,28 kcal/kg °C, 0,31 kcal/kg °C e a -196 °C foram de 0,25 kcal/kg °C e 0,28 kcal/kg °C, respectivamente. A difusividade efetiva média do camarão com exoesqueleto às temperaturas de -20 °C, -170 °C e -196 °C, foi de 9,13 x 10 3 mm2/s; 29 x 10 3 mm2/s; 571,8 x 10 3 mm2/s e para o filé nas mesmas temperaturas foi 9,9 x 10 3 mm2/s; 28,1 x IO"3 mm2/s; 384,3 x IO"3 mm2/s. A condutividade térmica média para o camarão com exoesqueleto às temperaturas de -170°C e -196 °C foi de 0,032 W/m °C e 0,499 W/m °C e para o filé nas mesmas temperaturas foi de 0,029 W/m °C e 0,371 W/m °C, respectivamente. Na caracterização físico-química, tanto nos camarões com cabeça quanto nos filés, congelados e armazenados em vapor de N2 (-170 °C) mantiveram-se inalterados o conteúdo de água, cinzas, proteínas, pH, gorduras e exsudado, durante todo o período de armazenagem. Os resultados das análises microbiológicas dos camarões frescos, depois de congelados e durante os 12 meses de armazenamento, apresentaram ausência de salmonela, de coliformes fecais e vibrio parahaemolyticus. Na avaliação sensorial quanto aos atributos sabor, odor, textura e aparência, os degustadores demonstraram preferência pelas amostras congeladas e armazenadas em vapor de N2, as amostras que tiveram menores índices de aceitabilidade foram às congeladas e armazenadas a -20 °C. Concluiu-se ainda que tanto no sabor, odor e textura, em todos os tratamentos, as médias das notas dos camarões descongelados em banho termostatizado à temperatura de 35 °C foram menores que as descongeladas a temperatura ambiente, todavia, na avaliação da aparência do camarão com exoesqueleto e cabeça, quando descongeladas em banho termostatizado a 35 °C, apresentaram notas mais elevadas que as descongeladas à temperatura ambiente, tal fato é atribuído a astaxantina existente em crustáceos, que quando aquecida dá a cor alaranjada ao camarão. / The objective of this research was to study the effect of techniques of: 1) freezing in temperatures of-20 °C, -196 °C and -170 °C; 2) storage in temperatures of (-20 °C, -30 °C and -170 °C, and 3) of unfreezing method ( environmental temperature: approximately 25 °C and in thermostatized bath: 35 °C) on two samples of shrimp: 1) with exoskeleton and head and 2) without exoskeleton and head, for a period of 12 months of storage. The following parameters had been determined: 1) physical characteristics (mass, length, thickness and volume); 2) kinetic freezing of temperatures at -20 °C, -170 °C and -196 °C; 3) thermophysical properties (density, specific heat, thermal diffusivity and thermal conductivity); 4) physicochemical characteristic (water content, ashes, proteins, pH, carbohydrates, fats, calories, exuded and an texture attribution: hardness); 5) microbiological characterization (salmonella, fecale coliform, vibrio parahaemolyticus) and 6) sensorial evaluation (flavor, scent, texture and appearance), aiming to verify the effectiveness of freezing and unfreezing techniques in the quality of the stored shrimp. During kinetic analysis, the curves of freezing obtained at the temperature of -20 °C for the shrimp with the head and exoskeleton for the filet, the three phases, or better saying, cooling, crystallization and after-freezing were clearly observed. This fact also occurred for the shrimp with frozen head at -170 °C, on the other hand for the filet at -170 °C, it was not easy to distinguish with clarity phase I from Phase II, in other words, the phases of cooling and crystallization, due to the speed of freezing. At the shrimps with head freezing curve, it was observed that when these were submitted to freezing by immersion in liquid N2 (-196 °C) there was not any distinction between the phases of cooling and crystallization. In relation to the thermophysical properties, the density of fresh shrimp (25 °C) with exoskeleton and head were of l,066g/cm3 and of that of filet was l,02g/cm3. The average values of the specific heat of the shrimp with exoskeleton and fresh filet is of 0,84 and 0,86 kcal/kg °C, respectively and for shrimp with exoskeleton and filet at temperature of -170 °C were of 0,28 kcal/kb °C, 0.31 kcal/kg °C and 196°C were of 0,25 kcal/kg °C and 0,28 kcal/kg °C, respectively. The medium diffusivity effectiveness of the shrimp with exoskeleton at the temperatures of -20 °C, -170 °C and -196 °C, was of 9,13 x 10"3 mm2/s; 29 x 10"3 mm2/s; 571,8 x 10"3 mm2/s and for the filet at the same temperature was 9,9 x 10"3 mm2/s temperatures was; 28.1 x 10"3 mm2/s; 384,3 x 10"3 mm2/s. The average thermal conductivity for shrimp with exoskeleton at -170 °C and -196 °C was of 0,032 W/m °C and 0,499 W/m °C and for filet at the temperature was of 0,029 W/m °C and 0.371 W/m °C, respectively. For physicist-chemistry characterization, both in shrimps with head as well as that of filet, frozen and stored in N2 vapor (-170 °C) the water content, proteins, pH, fats and exuded remained unchanged during all the period of storage. The results of the microbiological analyses of the fresh shrimps, after been frozen and during 12 months of storage, presented absence of salmonella, fecal coliform and vibrio parahaemolyticus. In the sensorial evaluation as much as flavor, scent, texture and appearance are concerned, the testators demonstrated preference for samples frozen and stored in vapor of N2, the samples with the least acceptability indices were those frozen and stored at -20 °C. It was concluded that in the flavor, scent and texture, in all the treatments, the average notes of defrosted shrimps in thermostatized bath of 35 °C temperature were less than those defrosted at environmental temperature, however, in the evaluation of the appearance of the shrimp with exoskeleton and head, when defrosted at thermostatized bath of 35 °C, presented higher notes than those defrosted at environmental temperature, such facts are attributed to astaxantine existing in crustaceans, which when heated, gives the shrimp that gives the orange color to the shrimp,