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A field experiment was designed to study the effect of nitrogen rates and application time on growth and yield of maize at Agronomy Research Farm, The University of Agriculture, Peshawar during summer 2014. An experiment was laid out in randomized complete block design using three replications. Four nitrogen rates (80, 120, 160 and 200 kg ha-1) were applied as full at sowing ( AT1), ½ at sowing + ½ at 25 days after sowing (AT2) and 1/3 at sowing + 1/3 at 25 days after sowing + 1/3 at 50 days after sowing (AT3). Results showed that all studied parameters were significantly affected by N-levels. Maximum mean leaf area (258.19 cm2), plant height (188 cm), grains ear-1 (369), 1000-grains weight (245 g), biological yield (9593 kg ha-1), grain yield (4109 kg ha-1) and harvest index (42 %) were observed with application of 160 kg N ha-1. The results further revealed that maximum mean leaf area (260 cm2), plant height (184 cm), grains ear-1 (380), biological yield (9195 kg ha-1), 1000-grains weight (247 g) and grain yield (3707 kg ha-1) were recorded when N was applied ½ at sowing + ½ at 25 days after sowing. The interactive effect of N rates and application time was found significant for mean leaf area. It was concluded that nitrogen at the rate of 160 kg ha-1 and application of N ½ at sowing + ½ at 25 days after sowing is most reliable for yield and production of maize crop in the study region and thus optional for general use in agriculture.
Keywords: Maize (Zea mays); Nitrogen rates; Application timing; Yield and yield components