Yield Response of Three Waxy Corn Varieties to Various Nitrogen Rates

บทคัดย่อ

Nitrogen fertilizer is generally considered as a yield-limiting factor in corn production. This study was conducted at the Rajamangala University of Technology Suvarnabhumi, during May to July 2008. The objective was to investigate suitable N fertilizer rates in growing waxy corn. A split-plot
design was used, with three waxy corn varieties (main plot), namely Neaw Sawan (NSW), Big White 852 (BW852) and Thein Ban Khao (TBK), and five nitrogen rates (sub plot) of 0, 75, 150, 225 and 300 kg ha^-1. The results showed that NSW gave the highest yield, yield components and the maximum leaf area. The maximum leaf greenness value and dry weight were observed in BW852. TBK rarely responded to various nitrogen rates. The application of nitrogen at rates of 150 kg ha^-1 up to 250 kg ha^-1 significantly increased the leaf greenness of all varieties and increased the dry weight and leaf area of BW852 and TBK, whereas NSW showed the highest dry weight and leaf area when nitrogen was applied at the rate of 75 kg ha^-1. The plant height of all varieties was not affected by variation in the nitrogen rate. The yield of all varieties tended to increase after applying nitrogen at 150 kg ha^-1 up to 250 kg ha^-1; however the optimum nitrogen rate to increase the yield of BW852 and NSW was 150 and 225 kg ha^-1, respectively, whereas there was no effect on the yield of TBK.