Nitrogen fertilization on dry bean leaves yield, SPAD reading, and nitrogen level

Nitrogen deficiency is one of the most limiting yield factors for dry bean. The objective of this study was to evaluate effects of topdressing nitrogen on chlorophyll and nitrogen concentrations in dry bean (BRS Horizonte cultivar) leaves and yield. The experiment was conducted at Embrapa Arroz e Feijão, in Santo Antônio de Goiás, Goiás State, Brazil, using a dystrophic dark red latosol. The experimental design was randomized blocks with four replications. The nitrogen rates used were 0 kg ha-1, 30 kg ha-1, 60 kg ha-1, 120 kg ha-1, and 240 kg ha-1. Half of the N was applied at 10 days after emergence and half was applied at 17 days after emergence, using urea as fertilizer. Grain yield and chlorophyll concentration showed quadratic response to increasing N rates, whereas N concentration in leaves increased linearly. The chlorophyll concentration increased according to plant age, while the N concentration in leaves decreased. Chlorophyll and N concentrations in leaves were positively associated with grain yield. Chlorophyll meter readings estimated adequately chlorophyll concentrations in dry bean leaves and can be used to diagnose this nutrient in dry bean.

Phaseolus vulgaris; chlorophyll meter; nitrogen level; no-till system

Escola de Agronomia/UFG Caixa Postal 131 - Campus II, 74001-970 Goiânia-GO / Brasil, 55 62 3521-1552 - Goiânia - GO - Brazil