Broccoli is a vegetable crop of increasing importance in Australia, particularly in south-east Queensland and farmers need to maintain a regular supply of good quality broccoli to meet the expanding market. However, harvest maturity date, head yield and quality are all affected by climatic variations during the production cycle, particularly low temperature episodes. There are also interactions between genotype and climatic variability. A predictive model of ontogeny, incorporating climatic data including frost risk, would enable farmers to predict harvest maturity date and select appropriate cultivar – sowing date combinations. The first stage of this research was to define floral initiation, which is fundamental to predicting ontogeny. Scanning electron micrographs of the apical meristem were made for the transition from the vegetative to advanced reproductive stage. During the early vegetative stage (stage 1), the apical meristem was a small, pointed shoot tip surrounded by leaf primordia. The transitional stage (stage 2) was marked by a widening and flattening to form a dome-shaped apical meristem. In the floral initiation stage (stage 3), the first-order floral primordia were observed in the axils of the developing bracts. Under field conditions, the shoot apex has an average diameter of 500 &plusmn; 3 µm at floral initiation and floral primordia can be observed under a light microscope. Sub-zero temperatures can result in freezing injury and thereby reduce head yield and quality. In order to predict the effects of frosts, it is desirable to know the stages of development at which plants are most susceptible. Therefore, the effects of sub-zero temperatures on leaf and shoot mortality, head yield and quality were determined after exposure of plants to a range of temperatures for short periods, at different stages of development (vegetative, floral initiation and buttoning). Plants in pots and in the field were subjected to sub-zero temperature regimes from –1 °C to –19 °C. Extracellular ice formation was achieved by reducing temperatures slowly, at a rate of -2 °C per hour. The floral initiation stage was most sensitive to freezing injury, as yields were significantly reduced at –1 °C and –3 °C, and shoot apices were killed at –5 °C. There was no significant yield reduction when the inflorescence buttoning iv stage was subjected to –1 °C and –3 °C. Although shoot apices at buttoning survived the –5 °C treatment, very poor quality heads of uneven bud size were produced as a result of arrested development. The lethal temperature for pot-grown broccoli was between –3 °C and –5 °C, whereas the lethal temperature for field-grown broccoli was between –7 °C and –9 °C. The difference was presumably due to variation in cold acclimation. Freezing injury can reduce broccoli head yield and quality, and retard plant growth. Crop development models based only on simple thermal time without restrictions will not predict yield or maturity if broccoli crops are frostdamaged. Field studies were conducted to develop procedures for predicting ontogeny, yield and quality. Three cultivars, (‘Fiesta’, ‘Greenbelt’ and ‘Marathon’) were sown on eight dates from 11 March to 22 May 1997, and grown under natural and extended (16 h) photoperiods in a sub-tropical environment at Gatton College, south-east Queensland, under non-limiting conditions of water and nutrient supply. Daily climatic data, and dates of emergence, floral initiation, harvest maturity, together with yield and quality were obtained. Yield and quality responses to temperature and photoperiod were quantified. As growing season mean minimum temperatures decreased, fresh weight of tops decreased while fresh weight harvest index increased linearly. There was no definite relationship between fresh weight of tops or fresh weight harvest index and growing season minimum temperatures > 10 °C. Genotype, rather than the environment, mainly determined head quality attributes. ‘Fiesta’ had the best head quality, with higher head shape and branching angle ratings than ‘Greenbelt’ or ‘Marathon’. Bud colour and cluster separation of ‘Marathon’ were only acceptable for export when growing season mean minimum temperatures were < 8 °C. Photoperiod did not influence yield or quality in any of the three cultivars. A better understanding of genotype and environmental interactions will help farmers optimise yield and quality, by matching cultivars with time of sowing. Crop developmental responses to temperature and photoperiod were quantified from emergence to harvest maturity (Model 1), from emergence to floral initiation (Model 2), from floral initiation to harvest maturity (Model 3), and in a combination of Models 2 and 3 (Model 4). These thermal time models were based on optimised base v and optimum temperatures of 0 and 20 °C, respectively. These optimised temperatures were determined using an iterative optimisation routine (simplex). Cardinal temperatures were consistent across cultivars but thermal time of phenological intervals were cultivar specific. Sensitivity to photoperiod and solar radiation was low in the three cultivars used. Thermal time models tested on independent data for five cultivars (‘Fiesta’, ‘Greenbelt’, ‘Marathon’, ‘CMS Liberty’ and ‘Triathlon’) grown as commercial crops on the Darling Downs over two years, adequately predicted floral initiation and harvest maturity. Model 4 provided the best prediction for the chronological duration from emergence to harvest maturity. Model 1 was useful when floral initiation data were not available, and it predicted harvest maturity almost as well as Model 4 since the same base and optimum temperatures of 0 °C and 20 °C, respectively, were used for both phenological intervals. Model 1 was also generated using data from 1979-80 sowings of three cultivars (‘Premium Crop’, ‘Selection 160’ and ‘Selection 165A’). When Model 1 was tested with independent data from 1983-84, it predicted harvest maturity well. Where floral initiation data were available, predictions of harvest maturity were most precise using Model 3, since the variation, which occurred from emergence to floral initiation, was removed. Prediction of floral initiation using Model 2 can be useful for timing cultural practices, and for avoiding frost and high temperature periods. This research has produced models to assist broccoli farmers in crop scheduling and cultivar selection in south-east Queensland. Using the models as a guide, farmers can optimise yield and quality, by matching cultivars with sowing date. By accurately predicting floral initiation, the risk of frost damage during floral initiation can be reduced by adjusting sowing dates or crop management options. The simple and robust thermal time models will improve production and marketing arrangements, which have to be made in advance. The thermal time models in this study, incorporating frost risk using conditional statements, provide a foundation for a decision support system to manage the sequence of sowings on commercial broccoli farms.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 6 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2008. / Härtill 4 uppsatser.

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-graduação em Agronegócios, 2008. / Submitted by Ruthléa Nascimento (ruthlea@bce.unb.br) on 2008-10-30T16:59:58Z No. of bitstreams: 1 2008_AnnaPaulaRDosSantos.pdf: 1108158 bytes, checksum: 629c12839d8137d3ffc51c4f65e12b63 (MD5) / Approved for entry into archive by Luanna Maia(luanna@bce.unb.br) on 2009-02-26T12:47:00Z (GMT) No. of bitstreams: 1 2008_AnnaPaulaRDosSantos.pdf: 1108158 bytes, checksum: 629c12839d8137d3ffc51c4f65e12b63 (MD5) / Made available in DSpace on 2009-02-26T12:47:01Z (GMT). No. of bitstreams: 1 2008_AnnaPaulaRDosSantos.pdf: 1108158 bytes, checksum: 629c12839d8137d3ffc51c4f65e12b63 (MD5) / A comercialização de hortaliças tem mudado muito nos últimos anos. A qualidade dos produtos e sua apresentação ao consumidor são as características mais marcantes nessa mudança. Hortaliças minimamente processadas são aquelas que foram fisicamente alteradas, mas que permanecem no estado fresco. As sucessivas manipulações na produção aumentam as possibilidades de contaminação microbiológica desses produtos. O objetivo deste trabalho foi avaliar a contaminação microbiológica por Salmonella sp. e coliformes a 45°C em dois elos da cadeia produtiva de couve minimamente processada para identificação do ponto crítico de contaminação. Foram coletadas amostras de couve na Agroindústria Machadinho, Brazlândia-DF, em todas as etapas do processo produtivo dentro da agroindústria, além de amostras coletadas em supermercados de Brasília-DF. Foi detectada contaminação por coliformes a 45°C apenas em amostras adquiridas nos supermercados. Verificou-se a necessidade de uma maior integração entre Agroindústria e supermercados, bem como a necessidade de treinamento de gerentes e manipuladores, e a aquisição de equipamentos objetivando a manutenção da qualidade ao longo da cadeia. _____________________________________________________________________________ ABSTRACT / The trade of vegetable crops has changed substantially in the last years. Quality and presentation of the products are the μost iμportant facts in this change. Miniμally processed vegetables are those that have been physically changed but have kept their fresh condition. The successive μanipulation increases the chance of μicrobiological contaμination of the products. The aiμ of this research was to evaluate the μicrobiological contaμination by Salμonella sp. and fecal coliforμes at 45°C in two segμents of the μiniμally processed Chinese kale to identify critical points. Saμples of μiniμally processed Chinese kale were colected froμ Agroindústria Machadinho, Brazlândia−DF, and froμ superμarkets in Brasilia DF. It was detected contaμination by fecal coliforμes at 45ºC in the saμples froμ the superμarkets. It was observed the need of a higher integration between the agroindustry and the superμarkets. It is also necessary training of μanagers and staff, as well as the acquisition of equipμents aiμing quality μaintenance in this supply chain.

Orientador: Arthur Bernardes Cecílio Filho / Coorientador: Hilário Júnior de Almeida / Banca: André Rodrigues dos Reis / Banca: Roberto Botelho Ferraz Branco / Banca: Priscila Lupino Gratão / Banca: Gilmara Pereira da Silva / Resumo: O objetivo deste trabalho foi avaliar concentrações de selênio (selenato e selenito de sódio) no crescimento, produção e biofortificação de duas cultivares de repolho. Para isso foram realizados dois experimentos em casa de vegetação, em sistema hidropônico, no período de julho a novembro de 2014, na UNESP, campus Jaboticabal-SP. Os experimentos diferiram conforme a fonte de selênio (Se) utilizada (selenato e selenito de sódio). Em ambos os experimentos, avaliaram-se dois fatores, sendo: duas cultivares de repolho ('Fênix' e 'Red Dinasty') e cinco concentrações de Se (0, 5, 15, 30 e 60 µmol L-1) na solução nutritiva. O delineamento experimental utilizado foi o de blocos casualizados, com esquema fatorial 2 x 5 e quatro repetições. As variáveis analisadas foram o teor e acúmulo de Se na raiz e cabeça de repolho, área, diâmetro, comprimento e densidade de raiz, produtividade de repolho, massa seca de raiz, caule e cabeça de repolho e o teor e acúmulo de nitrogênio, fósforo e enxofre na cabeça de repolho. As fontes selenato e selenito promoveram o crescimento das raízes de repolho devido aos aumentos verificados em área, diâmetro, comprimento e densidade de raiz, em baixas concentrações de Se aplicadas. O aumento da produção de massa seca de raiz provavelmente foi devido o maior crescimento da raiz, que foi influenciado pelo fornecimento de Se. A massa seca do caule foi diferente apenas entre as cultivares de repolho com aplicação de selenato ou selenito. O teor de nitrogênio ap... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of this research was to evaluate concentrations of selenium (sodium selenate and selenite) in the growth, production and biofortification of two cabbage cultivars. Two experiments were carried out in greenhouse under hydroponic system, from July to November, 2014, at UNESP, Jaboticabal-SP campus. The experiments differed according to the source of selenium (Se) used (sodium selenate and selenite). In both experiments two factors were evaluated: two cabbage cultivars ('Fênix' and 'Red Dinasty') and five concentrations of Se (0, 5, 15, 30 and 60 μmol L-1) in the nutrient solution. The experimental was a randomized block design, with 2 x 5 factorial and four replications. The variables analyzed were the content and accumulation of Se in the root and shoot cabbage, evaluating area, diameter, length, density and dry mass in the root, cabbage yield, stem and cabbage head, and the content accumulation of nitrogen, phosphorus and sulfur in the cabbage shoot. Selenate and selenite sources promoted the growth of cabbage roots due to increases in area, diameter, length and root density at low concentrations of Se applied. The increase in root dry mass production was probably due to higher root growth, which was influenced by the supply of Se. The dry mass of the stem was different only between the cabbage cultivars with application of selenate or selenite. The nitrogen content presented differences only among the cultivars when the selenite source was used. Both S sources ... (Complete abstract click electronic access below) / Doutor