Maintaining the structural integrity of cell walls largely determines the texture of fruit products during freezing processes. Strawberries undergo major textural changes when frozen, and varietal differences in quality after thawing are not readily predicted from mechanical and sensory testing of the fresh fruit. The objectives of this study were to develop a quantitative sensory texture profile of three strawberry varieties, individually quick frozen (IQF), to determine differences in cell wall composition and structure, and to relate the sensory and compositional profiles to differences in instrumental values of firmness. Intervarietal differences in IQF strawberries of Benton, Totem, and Selva varieties were examined and a summary of major findings follows. Drip-loss measurements, and work-of-compression on thawed berries were correlated to sensory ratings. Puree viscosity was highest in Selva samples, lowest in Bentons and shows potential as a screening test for strawberry cultivars. Firmness of thawed, whole Selva berries was rated 4x and 2x as compared to Bentons and Totems, respectively, via sensory profile evaluation with magnitude estimation scaling. Fractionation of fruit cell walls showed Selva had the highest percentages of acetone-insoluble solids. Total pectin content and absolute weight percentages of uronic acids and neutral sugars did not show major differences. Ratios of: 1) uronic acids to neutral sugars, 2) uronic acids to rhamnose, and 3) neutral sugars to rhamnose followed trends of increasing with varietal firmness in water-soluble polysaccharides (WSP) and decreasing in chelator-soluble polysaccharides (CSP). Ratios of galactose to arabinose decreased with increasing firmness scores in WSP and increased in CSP. Selva had the highest amount of high molecular-weight polymers in water-soluble and chelator-soluble polysaccharides. / Graduation date: 1986

Pectic substances in the cell wall have long thought to be responsible for the textural changes in fruit during ripening and senescence. Compositional variation within the pectic macromolecules could affect the external characteristics of the fruit. Strawberries undergo adverse quality changes such as softening and juice loss after freezing and subsequent thawing. To obtain a desirable cultivar that retains sound textural qualities after processing has long been an objective of both strawberry breeders and food processors. The fruit of Selva is exceptionally firm and some may consider it to be too firm. The purpose of this study was to investigate the compositional factors that would account for the unusual textural qualities of the Selva strawberry. Two major Oregon-grown commercial cultivars, Totem and Benton, were also included to facilitate comparisons between pectic substances and textural profiles of strawberry fruits. Fruit firmness was measured by the resistance of berry halves to shear and the amount of juice released after thawing. Very firm characteristic of Selva fruit was documented in that the shear value of thawed Selva was equal to fresh Totems and even greater than that of fresh Bentons. Juice-release after thawing was lowest in Selva samples. The quantity of acetone-insoluble solids obtained from freeze-dried powders of strawberry fruits was high for Selva and Benton, and low for Totem. Selva contained higher amounts of total soluble polyuronides and lower quantities of hemicellulose fraction as compared to Totem and Benton. Elution profiles of water-soluble polyuronides and chelator-soluble polyuronides from DEAE ion-exchange chromatography showed that Selva samples had a longer retention time and wider peak distribution, suggesting that its pectin species were of higher molecular weight and/or charge than Totem or Benton samples. The elution profile of ripe Selva was similar to that of underripe Totem and Benton. Ratios of uronic acid to rhamnose, indicating the extent of kinking and branching, were high for Selva and Totem in the water-soluble fraction and for Selva in the chelator-soluble fraction. Arabinose and galactose levels were relatively high in Selva base soluble polysaccharides, indicating that an arabinogalactan may be present in the hemicellulose fraction. This arabinogalactan may play a role in connecting the rhamnogalactan to the glycoprotein in the cell wall. / Graduation date: 1987

The Pacific Northwest is recognized for producing high quality strawberries (Fragaria x ananassa Duch.). Unfortunately, these are produced over an extremely short season of no more than 4 weeks. This situation is ideal for the processing market but not the fresh market where an extended season is essential. However, the recently introduced production systems together with the introduction of the day neutral cultivars have the potential to extend the season. The purpose of the present investigations was to examine these systems and the various day neutral cultivars in southwestern British Columbia. The production systems investigated were the waiting bed and the raised hill row. Both systems involve traditional June-bearing (short day) cultivars planted sequentially, resulting in a harvest season of at least 10 weeks. Among the cultivars tested in the waiting bed system, ‘Rainier’ was the most promising and 'Hood' the least; 'Totem' and ‘Shuksan’ gave intermediate responses. In the hill row 'Rainier' was again the most promising. However, in the second year of both systems, when production occurs in the traditional 4 week time period, 'Totem' was the most promising. Comparing the 2 systems, hill rows were more profitable than waiting beds. Day neutral cultivars begin flowering approximately one month after planting, and fruiting occurs from June or early July until October. In these investigations, they were grown at various spacings on raised beds, covered with black plastic mulch and trickle irrigated. The most promising cultivars tested were 'Selva' and 'Tribute' and the most promising spacing was 30 cm. / Land and Food Systems, Faculty of / Graduate

Made available in DSpace on 2014-06-11T19:26:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-01Bitstream added on 2014-06-13T20:34:41Z : No. of bitstreams: 1 gomes_er_me_botfca.pdf: 941970 bytes, checksum: 39260445a5a727a2cbfd5a375221f256 (MD5) / O morangueiro é uma cultura de clima temperado que demanda práticas culturais elaboradas para viabilizar seu cultivo. Dentre estas práticas, a irrigação fornecida por gotejamento visa suprir as necessidades hídricas da planta, em caráter total ou suplementar. Por outro lado, a adubação empregada no cultivo do morango é um dos insumos que gera alto custo na produção. O objetivo do presente estudo foi avaliar as necessidades hídricas da cultura de morango e seu manejo, visando elevar sua produtividade. Além disso, estudou-se a nutrição potássica da cultura, através da aplicação de diferentes doses do nutriente via fertirrigação em combinação com lâminas de irrigação (125%, 100%, 75%, 50% e 25% com base na tensão de água no solo), com o finalidade de elevar a qualidade dos frutos. O experimento foi conduzido em estufa de forma convencional. Em relação à nutrição potássica, foram aplicados três doses na forma K2SO4 as quais consistiram de uma adubação convencional (300 kg ha-1), uma superdose do nutriente equivalente a 3 vezes a dose recomendada (900 kg ha-1) e ausência completa de adubo potássico. Os tratamentos foram dispostos em delineamento experimental em blocos casualizados, com parcelas subdivididas com quatro repetições. A boa disponibilidade de água relacionada com a adubação potássica recomendada proporcionou a maior produtividade, crescimento das plantas e maiores frutos. Quando associadas menor disponibilidade de água e maior adubação potássica as características químicas dos frutos apresentaram melhores resultados. Entretanto, a menor disponibilidade de água e maior adubação potássica proporcionaram problemas fisiológicos e bioquímicos nas plantas / Strawberry is a culture of temperate climate that requires cultural practices developed to make possible its cultivation. Among these practices, the drip irrigation aims to supply the plant water needs, on a full or supplementary way. On the other hand, the fertilizer used in the strawberry cultivation is one of the inputs that generate high cost in production. The aim of this study was to evaluate the strawberry crop water requirements and its management in order to increase the productivity. In addition, we studied the potassium nutrition of the crop using the application of different concentrations of the nutrient by fertigation combined with irrigation water depths (125%, 100%, 75%, 50% and 25% based on the soil water tension) with the purpose of increasing the quality of the fruit. The experiment was conducted in a greenhouse in a conventional way. Regarding to the potassium nutrition, three doses were applied in the K2SO4 form according to the following manners: 1) conventional fertilization (300 kg ha-1); 2) overdose of the nutrient equivalent to three times the recommended dose (900 kg ha-1); 3) absence of potassium fertilizer. The treatments were arranged in a randomized complete block design with split plot with four replications. The good water availability correlated with the recommended dose of potassium fertilizer provided the highest productivity, greater plant growth and larger fruits. When associated the lower water availability with the higher potassium fertilization dose the chemical characteristics of the fruits showed the better results. However, the lower availability of water and the higher potassium fertilization dose have caused physiological and biochemical problems in the plants.

Orientador: Antônio de Pádua Sousa / Coorientador: Valdemício Ferreira de Sousa / Banca: Fernando Broetto / Banca: Edson Eiji Matsura / Resumo: O morangueiro é uma cultura de clima temperado que demanda práticas culturais elaboradas para viabilizar seu cultivo. Dentre estas práticas, a irrigação fornecida por gotejamento visa suprir as necessidades hídricas da planta, em caráter total ou suplementar. Por outro lado, a adubação empregada no cultivo do morango é um dos insumos que gera alto custo na produção. O objetivo do presente estudo foi avaliar as necessidades hídricas da cultura de morango e seu manejo, visando elevar sua produtividade. Além disso, estudou-se a nutrição potássica da cultura, através da aplicação de diferentes doses do nutriente via fertirrigação em combinação com lâminas de irrigação (125%, 100%, 75%, 50% e 25% com base na tensão de água no solo), com o finalidade de elevar a qualidade dos frutos. O experimento foi conduzido em estufa de forma convencional. Em relação à nutrição potássica, foram aplicados três doses na forma K2SO4 as quais consistiram de uma adubação convencional (300 kg ha-1), uma superdose do nutriente equivalente a 3 vezes a dose recomendada (900 kg ha-1) e ausência completa de adubo potássico. Os tratamentos foram dispostos em delineamento experimental em blocos casualizados, com parcelas subdivididas com quatro repetições. A boa disponibilidade de água relacionada com a adubação potássica recomendada proporcionou a maior produtividade, crescimento das plantas e maiores frutos. Quando associadas menor disponibilidade de água e maior adubação potássica as características químicas dos frutos apresentaram melhores resultados. Entretanto, a menor disponibilidade de água e maior adubação potássica proporcionaram problemas fisiológicos e bioquímicos nas plantas / Abstract: Strawberry is a culture of temperate climate that requires cultural practices developed to make possible its cultivation. Among these practices, the drip irrigation aims to supply the plant water needs, on a full or supplementary way. On the other hand, the fertilizer used in the strawberry cultivation is one of the inputs that generate high cost in production. The aim of this study was to evaluate the strawberry crop water requirements and its management in order to increase the productivity. In addition, we studied the potassium nutrition of the crop using the application of different concentrations of the nutrient by fertigation combined with irrigation water depths (125%, 100%, 75%, 50% and 25% based on the soil water tension) with the purpose of increasing the quality of the fruit. The experiment was conducted in a greenhouse in a conventional way. Regarding to the potassium nutrition, three doses were applied in the K2SO4 form according to the following manners: 1) conventional fertilization (300 kg ha-1); 2) overdose of the nutrient equivalent to three times the recommended dose (900 kg ha-1); 3) absence of potassium fertilizer. The treatments were arranged in a randomized complete block design with split plot with four replications. The good water availability correlated with the recommended dose of potassium fertilizer provided the highest productivity, greater plant growth and larger fruits. When associated the lower water availability with the higher potassium fertilization dose the chemical characteristics of the fruits showed the better results. However, the lower availability of water and the higher potassium fertilization dose have caused physiological and biochemical problems in the plants. / Mestre

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2007. / Härtill 4 uppsatser.

Indiana University-Purdue University Indianapolis (IUPUI) / Winter survival is variable among commercially grown strawberry (Fragaria x ananassa) cultivars. The main objectives of this study were to evaluate the molecular basis that contribute to this difference in strawberry cultivars and to identify potential biomarkers that can be used to facilitate the development of new strawberry cultivars with improved overwintering hardiness. With these goals in mind, the freezing tolerance was examined for four cultivars, ‘Jonsok’, ‘Senga Sengana’, ‘Elsanta’, and ‘Frida’ (listed from most to least freezing tolerant based on survival from physiological freezing experiments) and the protein expression was investigated in the overwintering relevant crown structure of strawberry. Biomarker selection was based on comparing the protein profiles from the most cold-tolerant cultivar, ‘Jonsok’ with the least cold-tolerant cultivar ‘Frida’ in a comprehensive investigation using two label-free global proteomic methods, shotgun and two dimensional electrophoresis, with support from univariate and multivariate analysis. A total of 143 proteins from shotgun and 64 proteins from 2DE analysis were identified as significantly differentially expressed between ‘Jonsok’ and ‘Frida’ at one or more time points during the cold treatment (0, 2, and 42 days at 2 ºC). These proteins included molecular chaperones, antioxidants/detoxifying enzymes, metabolic enzymes, pathogenesis related proteins and flavonoid pathway proteins. The proteins that contributed to the greatest differences between ‘Jonsok’ and ‘Frida’ are candidates for biomarker development. The novel and significant aspects of this work include the first crown proteome 2DE map with general characteristics of the strawberry crown proteome, a list of potential biomarkers to facilitate the development of new strawberry cultivars with improved cold stress tolerance.