Effect of nitrogen foliar application on grain filling rate and period in 3 cultivars of corn ( Zea mays L.)

In order to study the effect of nitrogen foliar application on seed rate and filing period in three cultivars of corn, a complete randomized block design base split plot experiment with three replications was conducted during 2009 at Agricultural Research Station, Islamic Azad University, Tabriz branch, Iran. Cultivars were arranged in three levels: early maturing (KSC307), average maturing (Jeta), and late maturing (KSC704). Urea foliar application arranged in seven levels: control (lack of foliar application), tassel appearance, ear appearance, beginning of grain filling, end of grain filling, concurrent foliar application in tassel appearance and beginning of grain filling stages and concurrent in tassel appearance, ear appearance, beginning of grain filling and end of grain filling. The results showed that foliar application of urea had a significant effect on grain yield. Yield increase with foliar application of urea took place in concurrent foliar application of urea in tassel appearance, ear appearance, beginning of grain filling and end of grain filling stage. Foliar application had a significant effect on leaf area duration and on grain filling rate and period consequently. According to the findings of this survey, it is possible to use foliar application of urea for increasing grain yield per plant and leaf area duration.   Key words: Foliar application, grain filling period, grain yield, leaf area duration, urea.