Influência da adubação nitrogenada e avaliação do estado de nitrogênio do arroz irrigado

• Autor(a) principal: Cardoso, Expedito Alves
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1165
• topic: Orizicultura; SPAD; Nutrição de plantas; Rice; SPAD; Plant nutrition; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

Experiments were carried out at the Experimental Station of the Federal University of Viçosa, Viçosa City, Minas Gerais State, Brazil, in 2008/09 crop, in order to investigate four tropical irrigated rice cultivars, subjected to six nitrogen doses for nitrogen use efficiency, nutrient uptake, grains productivity, and benefited grains produtivity. In addition, nitrogen status of plants was evaluated by the leaf N content method, SPAD, measuring tape, and color table in three periods (25, 40, and 55 days) after transplanting. The design was randomized blocks with five replications in a split-plot. Nitrogen doses of 0, 50, 100, 150, 200, and 400 kg.ha-1 were the main plot and the cultivars BRS Alvorada, BRS Jaçanã, BRS Tropical e Metica1 were subplots. All yield components showed responses to nitrogen. The mass of 1.000 grains showed significant difference among cultivars, and the BRS Tropical presented the higher average over the others in all treatments. Significant differences among cultivars for grains yield were not verified, however we obtained a quadratic response to nitrogen. The number of panicles/m2 was the component that presented more closely related to grains yield that was the highest economic with 254 kg.ha-1. Nitrogen fertilization also influenced the absorption of macronutrients N, P, K, Ca, Mg, and S. From the standpoint of quality, nitrogen fertilization positively affected the yield of whole grains, feature dependent on cultivar. There was no significant interaction among N doses and cultivars and cultivars from each other, as well as cultivars on the values of the SPAD readings, measuring tape, color table, and leaf N content. For three seasons, SPAD methods, measuring tape, and color table presented sensitivity for assessing N from the plant. Except SPAD, these methods are alternatives presenting the advantage of a lower cost.