EFFECTS OF NITROGEN AT DIFFERENT GROWTH STAGES ON PHENOLOGY AND GRAIN FILLING PERIOD OF MAIZE (ZEA MAYS L.)

An experiment was conducted to see the effects of nitrogen at different growth stages on phenology, rate and grain filling period of maize. Nitrogen rates (0, 75, 150 and 225 kg/ha) were arranged in main plot and time of nitrogen application in sub plots [(1/3 at sowing + 1/3 at V8-10 + 1/3 at tasseling), CA at sowing + 1/2 at tasseling) and (1/2 at sowing+ 1/4 at V8-10 + 1/4 at tasseling) as T-1, T-2 and T-3, respectively]. A two part linear model was used to quantify the grain filling parameters. Application of high N rates as T-1 resulted 33% increase in potential rate of grain filling compared with the control. Maximum rate (0.00904 g/day), grain filling period (42.64 days), effective grain filling period (37.72 days), maximum grain yield (7700 kg/ha), days to 50% anthesis (63.85 days), days to 50% silking (68.2 days) and days to physiological maturity (128.9 days) were observed in the plots receiving 225 kg N/ha as T-1. It was vice versa in tasseling-silking interval. Results suggested that application of 225 kg N/ha in three equal splits can be recommended for profitable maize production in the study area.