Effect of Nitrogen Fertilizer on Grain Yield and Nitrogen Use Efficiency in Corn (Zea mays L.) Hybrids Under Irrigated Conditions

Abstract

In order to study the effect of nitrogen rates on grain yield and nitrogen use efficiency of corn (Zea mays L.) hybrids, a field experiment was conducted in south-western Iran during 2011–2012. The experiment was split-plot with RCBD arrangement in three replications. Main plots consisted of four nitrogen rates (0, 90, 180 and 260 kg N ha−1) and four corn hybrids (Sc.704, Sc.640, Mobeen and DKC6589) were placed in sub-plots. Results indicated that the effect of nitrogen, hybrids and their interaction on corn grain yield was significant. Increase in nitrogen rates from 0 to 90, 180 and 260 kg N ha−1 increased the mean grain yield studied hybrids by 42.6, 55 and 58 %, respectively. DKC6589 hybrid and Mobeen had the highest and lowest grain yield among studied hybrids. Higher grain yield in DKC6589 was due to higher number of grains per ear and 100-grain weight. The results of step-wise regression coefficients also indicated that number of grains had the maximum contribution in grain yield. As compared to grain yield of Mobeen and Sc.640 hybrids at the levels of 180 and 260 kg N ha−1, DKC6589 hybrid yield was more in the treatment of no nitrogen. The maximum grain yield was obtained in DKC6589 hybrid and 180 kg N ha−1. Increase of nitrogen up to 260 kg N ha−1 led to the significant increase in grain yield of 640 hybrid, but in other hybrids, increase of nitrogen up to more than 180 kg N ha−1, slightly decreased the grain yield. There was genetic variation for nitrogen use efficiency. It is possible to select hybrids with higher nitrogen use efficiency to reduce the fertilization. Positive and significant relation between grain yield and nitrogen use efficiency was marked. DKC6589 hybrids as compared to other hybrids had more nitrogen use efficiency and agronomic nitrogen use efficiency in lower amount of fertilizer. Generally, it seemed that DKC6589 hybrid had all ideal traits of implantation in the region as the potential of its grain yield was very high.