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Nova Londrina, Brazil

Ohlson O.C.,CLASPAR | Krzyzanowski F.C.,Pesquisador da Embrapa Soja | Caieiro J.T.,CLASPAR | Panobianco M.,Federal University of Parana
Revista Brasileira de Sementes | Year: 2010

The wheat sown in southern Brazil has shown serious seed quality problems but standard procedures for determining the wheat seed vigor is missing from the literature. This project aimed to study the methodology of the accelerated ageing test to identify levels of vigor in wheat seed lots. Seeds of the wheat cultivars CD 104 and BRS 220 were used, each represented by five lots. The following tests were conducted: determination of moisture content (oven, 105 ± 3 °C, 24 h), standard germination (8×50 seeds, 20 °C) field seedling emergence, accelerated ageing (41 °C / 48, 60 and 72 hours, and 43 °C / 48 hours). Means were compared using the Tukey test at the 5% probability level; the Spearman rank correlation test was used for the study on the methodology of the accelerated ageing test, where a measure of the strength of the relationship between the test data and existing data on seedling emergence in the field was looked for. From the results, it was concluded that the accelerated ageing test at 43 °C for 48 h provides consistent information for differentiating between wheat seed lots. Source

Daltro E.M.F.,Pesquisadora da EMPAER MT | Albuquerque M.C.F.,Federal University of Mato Grosso | Neto J.B.F.,Pesquisador da Embrapa Soja | Guimaraes S.C.,Federal University of Mato Grosso | And 2 more authors.
Revista Brasileira de Sementes | Year: 2010

Temperature fluctuations associated with high rainfall and the oscillating relative humidity of the air during the pre-harvest stages of seed maturation may result in losses in physical and physiological quality and also in seed health. Pre-harvest desiccant application helps to reduces seed exposure to unfavourable climate conditions and reduce seed vigor and germination. The object of this research was to determine the effects of the application period of desiccants and of early harvesting on soybean seed quality. The experiments were conducted in Alto Garças, MT, with the cultivars MG/BR-46 Conquista and FMT Tucunaré in the 2005/2006 growing season, and with BRS MT Pintado and FMT Tucunaré in 2006/2007. The experimental design was a randomized block in a factorial arrangement 6x2x2x2 [6 treatments (5 desiccants and 1 control), 2 application times, 2 harvest times and 2 storage periods]. Five desiccant treatments were evaluated: paraquat, diquat, paraquat + diquat, paraquat + diuron and glyphosate, applied at the R6.5 and R7 growing stages, which were compared to a control treatment. Seeds were harvested at two stages: first, when moisture content reached 17% to 20% (early harvest), and secondly, 12% to 13% (normal harvest). Seeds from early harvesting were dried to 12% to 12.5% moisture content in a forced air chamber at temperatures ranging from 38 °C to 40 °C. Seed quality was evaluated by the following tests: germination, seedling vigor classification, tetrazolium, field seedling emergence and seedling growth. Paraquat, diquat, paraquat + diquat and paraquat + diuron as pre-harvest desiccants do not affect seed physiological quality but glyphosate causes phytotoxic damage to seedling roots. With the exception of glyphosate, pre-harvest desiccation at the R6.5 and R7 growth stages results in the production of seeds having a similar quality. Early harvest results in the production of higher quality seeds compared to those from a normal harvest. Source

Zobiole L.H.S.,State University of Maringa | de Castro C.,Pesquisador da Embrapa Soja | de Oliveira F.A.,Pesquisador da Embrapa Soja | de Oliveira Junior A.,Pesquisador da Embrapa Soja
Revista Brasileira de Ciencia do Solo | Year: 2010

This study aimed to establish curves of macronutrient accumulation in sunflower. The experiment was conducted in the field on a Typic Hapludox, at the experimental station of Embrapa Soja in Londrina, State of Paraná. The plots consisted of 14 25 m long rows spaced 0.70 m apart, resulting in a total area of 245 m2, with four replications. Prior to sowing a fertilization seeding of 300 kg ha-1 of 05-20-20 NPK fertilizer was applied. Fertilization was split in two applications of 25 + 1 kg ha-1 N and B, which were applied 21 and 35 days after sowing, respectively. The hybrid BRS 191 and a final plant density of 40,000 plants ha-1 were used. Plant samples were collected every two weeks after emergence and separated in the different parts (petioles, leaves, stems and, when applicable, capitula and achenes). After drying, each plant part was weighed and ground to determine the N, P, K, Ca, Mg, and S content. From the contents of these nutrients and dry mass of each plant, the accumulation curve was obtained. It was found that for yields > 3,000 kg ha-1, BRS 191 extracted about 150, 24, 286, 116, 42, and 24 kg ha-1 of N, P, K, Ca, Mg, and S, respectively, in the following order of extraction: K> N> Ca> P = S. In addition to the relation to exportation, the nutrient order was: N> P = K> S = Mg> Ca. Therefore, special attention should be paid to the maintenance of an adequate supply of N, K and Ca, due to the high demand of sunflower. Source

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