Nitrogen application in direct wet-seeded rice under alternate wetting and drying irrigation condition: Effects on grain yield, dry matter production, nitrogen uptake and nitrogen use efficiencies

ABSTRACT

Yield, dry matter production, nitrogen (N) uptake and nitrogen use efficiency (NUE) of Bangladesh Rice Research Institute (BRRI) dhan29 were investigated during two consecutive dry (Boro) seasons of 2009–10 and 2010–11. The experiments were set up in a randomized complete block design with three replication having six nitrogen (N) levels of 0, 40, 80 120, 160 and 200 kg ha⁻¹. Nitrogen fertilization increased yield characters, dry matter production and N uptake. The economic optimum rate of N was 166 and 155 kg ha^–1 in first and second year, respectively, with corresponding yield of 7.1 and 6.5 t ha⁻¹. NUEs were higher in the first year, decreased with increasing N rates in most cases. Gross return over fertilizer reached the highest Tk 692 in 2009–10 and Tk 489 in 2010–11 with 160 kg N ha^–1. The results suggest that BRRI dhan29 should receive an average of 160 kg N ha⁻¹ for economic optimum yield.

KEYWORDS:

• direct wet-seeded rice
• nitrogen use efficiencies
• nitrogen uptake and dry matter production