Effects of Irrigation Interval and Manure Application on Growth and Yield of Field-Grown Maize in Thailand

抄録

Utilizing less water while maintaining yields is vital to sustain the irrigated maize (Zea mays L.) production in Thailand. In a field experiment, maize plots were fertilized with three levels of manure (0, 6.25, and 12.5 t ha^-1) and furrow irrigation was conducted at 1-, 2-, and 3-week intervals from 43 to 92 days after sowing. Lengthening the irrigation interval to 2 and 3 weeks reduced irrigation water by 29% and 36%, respectively. Lengthening the irrigation interval inhibited plant height, while the application of manure promoted plant height at the vegetative stage. Photosynthetic rates at early ripening stage, dry weight at maturity, and grain yield were markedly inferior in the 3-week interval irrigation, but there was no significant difference between 1- and 2-week interval irrigation groups. Application of manure slightly increased dry weight, grain yield, and water use efficiency, although the difference was not significant, probably due to insufficient manure levels or clayey soil. Lengthening irrigation interval increased carbon isotope discrimination, indicating that the relative activity of C₃ to C₄ photosynthetic pathway declines. In a pot experiment, manure application alleviated growth inhibition, yield reduction, and increase in carbon isotope discrimination caused by soil water stress. These results suggest that the lengthening irrigation interval from the late vegetative to the early ripening stage to 2 weeks saves water without affecting growth and yield, and manure application may enhance dry matter production and increases grain yield.