CORRELATIONS AMONG GRAIN YIELD AND YIELD ATTRIBUTES IN MAIZE HYBRIDS AT VARIOUS NITROGEN LEVELS

Three maize hybrids (Baber, Pioneer 30P45 and Syngenta 6621) were compared for yield and yield components and correlations were worked out among the yield parameters at various nitrogen levels in an experiment conducted at Agricultural University, Peshawar, Pakistan during summer 2009. The experiment was laid out in randomized complete blocks with split plot arrangement having three replications. Nitrogen levels (0, 180, 240 and 300 kg ha^-1) were allotted to main-plots and hybrids to subplots. The higher levels of 240 and 300 kg N ha^-1 recorded maximum and at par number of 1.3 and 1.2 ears plant^-1, ear lengths of 14 and 13.5 cm, grains ear^-1 of 422.1 and 481.2, 1000 grain weight of 280.56 and 303.68 g, grain yield of 3281.3 and 3696 kg ha^-1, biological yield of 10889 and 11830 kg ha^-1 and harvest indices of 30.1 and 31.42%, respectively. Syngenta 6621 recorded larger ear length of 14.6 cm, larger number of 451.5 grains ear^-1, higher 1000 grain weight of 275.24 g, higher grain yield of 3033.8 kg ha^-1 and higher biological yield of 11555.9 kg ha^-1. All these values were statistically equal to those recorded by Pioneer 30P45. Pioneer 30P45 recorded the highest harvest index of 27.8%. The interaction of nitrogen and hybrids affected grains ear^-1, grain yield, biological yield and harvest index substantially. When the nitrogen level was increased from 0 to 300 kg ha^-1, ears plant^-1 of Syngenta 6621, Pioneer 30P45 and Baber increased by 20%, 20% and 10%; grains ear^-1 by 89%, 55% and 30.7%; thousand grain weight by 37.2%, 29.8% and 45.7%; grain yield by 143%, 151% and 102%; biological yield by 68%, 50.4% and 49.5% while harvest index increased by 45.5%, 66.5% and 36.3%, respectively. It was concluded that among the three yield attributes, ear plant^-1 contributed 14.8%, grains ear-1 51.8% and 1000 grain weight contributed 33.4% to the average increase of 132% in the grain yield of hybrids. Based upon the correlations, ear length was also found a suitable marker for selecting a maize hybrid for higher grain yield along with other yield attributes i.e. ears plant-1, grains ear^-1 and 1000 grain weight.