Corn Leaf Orientation Effects on Light Interception, Intraspecific Competition, and Grain Yields

Current environmental concerns justify renewed evaluation of crop management strategies that offer promise for maintaining or increasing productivity while reducing environmental impacts. Field studies were conducted using weed-free conditions to determine the effects of corn (Zea mays L.) leaf orientation on light interception, vegetative and reproductive development, and grain yields. DeKalb 689' was handseeded in north-south rows to achieve populations of 22 000 and 33 000 plantslacre. Controlled seed positioning in the soil was used to attain across-row and with-row leaf orientations, while conventional planting provided random leaf orientation. Light interception, intraspecific competition among corn plants, and grain yield were affected by leaf orientation and plant population. At selected row positions 8 wk after planting, light interception for across-row leaf orientation exceeded random and with-row orientations by up to 10 and 25%, respectively, while light interception for the high plant population exceeded the low population by up to 15%. Across-row and random leaf orientations produced 8% greater leaf area than with-row orientation. Greater intraspecific competition was indicated for the high plant population due to lower leaf area, leaf biomass, and stalk biomass per plant than the low population. Grain yields were greater at the high than the low plant population for all leaf orientations. At the high plant population, across-row leaf orientation yielded 10 and 21% more than random and with-row orientations, respectively. Therefore, across-row leaf orientation at the high plant population should provide more rapid canopy closure, enhance crop competition with weeds, and reduce dependence on herbicides while enhancing grain yields.