Abstract

Nitrogen and irrigation, both are essential to determine the yield and quality of maize (Zea mays L.). A field study was accomplished to determine the upshots of different levels of irrigation and varying nitrogen rates on yield, yield contributing attributes and radiation use efficiency (RUE) of maize hybrid on sandy clay loam soil. Different nitrogen rates and moisture regime treatments comprised of N₀ = 0, N₁ = 100 and N₂= 200kg N ha^-1, I₁ (25 mm water deficit), I₂ (50 mm water deficit), I₃ (three irrigations during vegetative development + one irrigation at tasseling stage) and I₄ (three irrigations during vegetative development + one irrigation at tasseling stage + one irrigation at silking stage + one irrigation at grain filling stage), respectively. Results showed that maximum grain yield (7.04 t ha^-1) was recorded when six irrigations were applied (three irrigations during vegetative development + one irrigation at tasseling stage + one irrigation at silking stage + one irrigation at grain filling stage) coupled with 200 kg N ha^-1 (N₂ × I₄). The lowest grain yield (2.08 t ha^-1) was obtained in response to 25 mm water deficits. Overall, N₂ × I₂ also gave a positive response in terms of yield attributes but highest plant height (160.80 cm), cob length (29.00 cm), number of grains per cob (308.33), 1000-grain weight (294.33 g) and biological yield (25.67 t ha^-1) with maximum coefficient of correlation (R²) values (0.9399; 0.8851; 0.9161; 0.8743 and 0.9126), respectively, was attained with N₂ × I₄ treatment combinations. The superior (RUE) radiation use efficiency (5.33 g MJ^-1) with higher R² value (0.8821) was significantly affected by nitrogen rates and irrigation levels as obtained from N₂ × I₄ treatment. However, in all treatment combinations, N₂ × I₄ was superior by producing the highest maize grain yield.

Key words: Moisture regimes, nitrogen rates, deficit irrigation, Zea mays L., radiation use efficiency, maize yield.