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NITROGEN DOSES AND APPLICATION TIMES IN LOWLAND RICE DOSES E ÉPOCAS DE APLICAÇÃO DE NITROGÊNIO EM ARROZ DE VÁRZEA

Aloísio Alcântara Vilarinho, Gilvan Barbosa Ferreira, Antônio Carlos Centeno Cordeiro and 2 more

Pesquisa Agropecuária Tropical · 2011

doi:10.5216/pat.v41i1.7776 (opens in a new tab)

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Abstract

The most outstanding crop, concerning agribusiness in the Roraima State, is lowland rice. Therefore, the recommendation of new cultivars, as well as the study of correct handling for nitrogen fertilizing, are important to maximize grain yield and reduce production costs and environmental impacts. Thus, the objective of this study was to identify the nitrogen doses and application times most adjusted to the rice cultivar BRS Ja&ccedil;an&atilde;, in Roraima lowlands. The experiment took place at the Santa Cec&iacute;lia Farm, a lowland area of the Rio Branco river, in Cant&aacute;, Roraima State, Brazil, from December (2007) to March (2008), on a tb distrophic haplic gleissol. The experiments were conducted under a split-plot scheme, with plots displayed under a randomized blocks design with four replicates. Treatments consisted of four N doses (50 kg ha-1, 100 kg ha-1, 150 kg ha-1, and 200 kg ha-1), combined with four application times: E1 - half dose at sowing and half 45 days after emergence (dae); E2 - half dose 15 days after emergence (dae) and half 45 days after emergence (dae); E3 - one application 15 days after emergence (dae); and E4 - one application 45 days after emergence (dae), totalizing 16 treatments and 64 experimental units. Concerning the BRS Ja&ccedil;an&atilde; lowland rice cultivar, the best combination was the application of 118 kg ha-1 of nitrogen, half at sowing and half 45 days after emergence. KEY-WORDS: Oryza sativa L.; lowland rice; maximum economic yield. &nbsp;    No Estado de Roraima, a cultura que mais se destaca no setor do agroneg&oacute;cio &eacute; a do arroz irrigado por inunda&ccedil;&atilde;o. Por isto, tanto a recomenda&ccedil;&atilde;o de novas cultivares, quanto o estudo do manejo correto da aduba&ccedil;&atilde;o nitrogenada s&atilde;o importantes para a maximiza&ccedil;&atilde;o da produtividade de gr&atilde;os e redu&ccedil;&atilde;o de custos de produ&ccedil;&atilde;o e impactos ambientais. Assim, o objetivo deste trabalho foi identificar as doses e &eacute;pocas de aplica&ccedil;&atilde;o de nitrog&ecirc;nio mais adequadas para a cultivar de arroz BRS Ja&ccedil;an&atilde;, em v&aacute;rzea de Roraima. O experimento foi conduzido na Fazenda Santa Cec&iacute;lia, em &aacute;rea de v&aacute;rzea do Rio Branco, no munic&iacute;pio de Cant&aacute;, no per&iacute;odo de dezembro de 2007 a mar&ccedil;o de 2008, em Gleissolo H&aacute;plico tb distr&oacute;f&iacute;co. Utilizaram-se parcelas subdivididas, distribu&iacute;das conforme delineamento em blocos casualizados, com quatro repeti&ccedil;&otilde;es. Os tratamentos foram constitu&iacute;dos de quatro doses de N (50 kg ha-1, 100 kg ha-1, 150 kg ha-1 e 200 kg ha-1), como subparcelas, combinadas com quatro &eacute;pocas de aplica&ccedil;&atilde;o, como parcelas: E1 - metade da dose na semeadura e metade aos 45 dias ap&oacute;s a emerg&ecirc;ncia (dae); E2 - metade da dose aos 15 e metade aos 45 dae; E3 - uma aplica&ccedil;&atilde;o, aos 15 dae; e E4 - uma aplica&ccedil;&atilde;o, aos 45 dae, totalizando 16 tratamentos e 64 unidades experimentais. Para a cultivar de arroz irrigado BRS Ja&ccedil;an&atilde;, a melhor combina&ccedil;&atilde;o foi a aplica&ccedil;&atilde;o de 118 kg ha-1 de N, distribu&iacute;dos metade na semeadura e metade aos 45 dias ap&oacute;s a emerg&ecirc;ncia. PALAVRAS-CHAVE: Oryza sativa L.; arroz irrigado; produtividade m&aacute;xima econ&ocirc;mica.

Abstract licence: CC BY

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