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Ciência e Agrotecnologia

versão impressa ISSN 1413-7054versão On-line ISSN 1981-1829

Resumo

BARBOSA FILHO, Morel Pereira; COBUCCI, Tarcísio; FAGERIA, Nand Kumar  e  MENDES, Patrícia Neves. Timing of nitrogen application on irrigated common bean measured by portable sensor. Ciênc. agrotec. [online]. 2009, vol.33, n.2, pp.425-431. ISSN 1413-7054.  http://dx.doi.org/10.1590/S1413-70542009000200010.

Defining the optimal timing of nitrogen application on a crop is fundamental to increase the efficiency of N use, increase the productivity and reduce the cost of fertilizers. The aim of this study was to evaluate methods and timing of N application for the common bean crop. The management technique consisted of N application previous to sowing, N application based on local recommendations, and based on the sufficiency of N evaluated through leaf chlorophyll content determined by the Minolta SPAD 502 Chlorophyll meter. Grain yield obtained with the application of N prior to sowing was similar to other periods of N applications. The nitrogen application indicated by ISN < 90% was promising in predicting the necessity of N topdressing resulting in minus 60 kg N ha-1 and higher agronomic efficiency of N use. Minimum critical levels of chlorophyll reading to obtain 90% maximum grain yield of dry bean were 42 unit-SPAD at 30 days after emergence and 46 days after emergence at full flowering of the bean plant.

Palavras-chave : Phaseolus vulgaris L; Nitrogen management; chlorophyll meter.

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