7 resultados para bioscience

em Repositório Alice (Acesso Livre à Informação Científica da Embrapa / Repository Open Access to Scientific Information from Embrapa)


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The objective of this work was to evaluate the biological variables of Spodoptera frugiperda on species of cover crops. The experiments were conducted in laboratory and greenhouse using the following species: sunflower (Helianthus annuus), sun hemp (Crotalaria juncea), brachiaria (Urochloa decumbens e Urochloa ruziziensis), millet (Pennisetum americanum), black oat (Avena stringosa), white lupin (Lupinus albus), forage turnip (Rafanus sativus) and maize (Zea mays). In laboratory the S. frugiperda larval survival varied from 57%, on L. albus, to 93% on H. annuus and the survival of the pre-imaginal phase varied from 45% on U. decumbens to 81.6% on Z. mays. On C. juncea the larval biomass was lower and the development period of the young and larval stage was higher. The adaptation index was less on C. juncea in greenhouse and laboratory. In greenhouse the larval survival at 14 days was similar for all plants and at 21 days was the lowest on C. juncea. There was less accumulation of biomass at 14 days on C. juncea and at 21 days on C. juncea and A. stringosa. Regarding damage, C. juncea presented less susceptibility to Spodoptera frugiperda attack, which together with the other evaluated parameters, indicated this plant as the most appropriate for soil cover before cultivation of maize.

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Urea is the most used N fertilizer for upland rice, however, a great percentage of N loss can occur with the use of this fertilizer. The use of products that provide reduction of N loss for urea fertilizers can contribute to increase N use efficiency. The objective of this study was to determine the effect of N rates applied in the form of coated urea in the content and accumulation of N in dry biomass, apparent recovery of nitrogen and grain yield of upland rice. The experimental design was a randomized complete blocks arranged in a 4 x 3 + 1 factorial scheme. The treatments consisted of four sources of N fertilizer [1. Common urea; 2. Polymer-coated urea for slow release of N (PCU); 3. urea with the urease inhibitor N-(n-Butyl) thiophosphoric triamide (NBPT); and 4. urea coated with copper sulfate and boric acid as urease inhibitors (UCCB)], with three fertilization rates (30, 60 and 90 kg ha-1 of N). In addition, we included a control treatment without N application. Coated urea did not provide increases in rice grain yield in relation to common urea. The increasing amount of N resulted in significant increases in rice grain yield (from 3217 to 5548 kg ha-1, 2010/11, and from 3392 to 4560 kg ha-1, 2011/12). The apparent nitrogen recovery rate decreased with the increase in N applied doses.