Effects of different nitrogen rates on chlorophyll content, leaf area index and grain yield of some maize cultivars.

This research was conducted to determine the effects of different nitrogen rates on chlorophyll content, leaf area index and grain yield of some corn varieties grown during 2010/2011 growing season at Agriculture Faculty, Uludag University. Two different maize varieties (89May70 and Shemal) and five different nitrogen rates (0, 240, 320, 400 and 480 kg/ha) were used in the experiment. The chlorophyll contents of plants at different growing stages (V8, V10, V12, Silking, R1 and R2) were measured by the tool of SPAD-502. The results indicated that the leaf area index values of the varieties differed only at the silking stage of the plants. Leaf area indexs and chlorophyll contents of maize varieties increased as the nitrogen rates increased at whole growing stages. The grain yield of Shemal variety (9247.8 kg/ha) was higher than that of 89May70 (8468.7 kg/ha). Increasing nitrogen rates affected grain yields of varieties and the highest yields were ontained at 400 and 480 kg/ha rates