Phenology, yields and their correlations in popular local and exotic maize hybrids at various nitrogen levels

Three maize hybrids including Baber (Local), Pioneer 30P45 and Syngenta 6621 (both are exotic) were compared phonologically and yield-wise; and correlations were worked out among the phenological and yield parameters at various nitrogen levels in an experiment conducted at KPK Agricultural University, Peshawar (34 degree 00' N, 71 degree 30' E, 510 MASL) Pakistan during summer 2009. The experiment was laid out in randomized complete blocks with split plot arrangement having three replications. Nitrogen levels (i.e. 0, 180, 240 and 300 kg per ha) were allotted to main-plots and hybrids to subplots. Result data showed that nitrogen levels affected various parameters significantly. The highest level of 300 and 240 kg N per ha recorded maximum and at par days to tasseling and maturity, plant height, stover and grain yields as well as harvest index. Among the hybrids, Pioneer 30P45 recorded significantly the highest number of days to emergence while Syngenta 6621 and Pioneer 30P45 recorded significantly higher and at par values for days to tasseling, silking, maturity as well as grain yield. Syngenta 6621 recorded significantly higher plant height and stover yield while Pioneer 30P45 and Baber recorded significantly higher and at par values for harvest index. The interaction of nitrogen and hybrids affected plant height, stover yield, grain yield and harvest index. When the nitrogen level was increased from 0 to 300 kg per ha, plant height of Syngenta 6621, Pioneer 30P45 and Baber increased by 6%, 3% and 2.5%, stover yield by 33%, 25% and 19%, grain yield by 59%, 60% and 51%, while harvest index increased by 45.5%, 66.5% and 36.3%, respectively. Based upon the significance of correlations, days to maturity and plant height were found suitable markers for selecting a maize hybrid for higher grain yield.