Effects of population density on the vegetative growth of leafy reduced-stature maize in short-season areas

Maize hybrids which produce more leaves above the ear, with leaf area indic es similar to conventional hybrids, which require fewer corn heat units to flowering and maturity, and tolerate higher population densities, should be better adapted for production in short season areas than currently availab le hybrids. Leafy reduced-stature maize hybrids, which have only recently b een developed, have traits which address these criteria. The objective of t his study was to evaluate the effects of different population densities (50 000, 100 000, 150 000, and 200 000 plants.ha(-1)) on the vegetative growth of one leafy reduced-stature (LRS), one non-leafy reduced-stature (NLRS), and two conventional control hybrids (Pioneer 3979, < 2500 CHU, and Pioneer 3902, 2600-2700 CHU) at two locations. There were no differences among pop ulation densities for leaf number above the ear; however leaf area index in creased as population density increased for all hybrids. The LRS hybrid had a greater average leaf number above the ear (2.7 and 2.0 more leaves than NLRS and the control hybrids, respectively). As a result the leaf area inde x value of LRS was much greater than the NLRS and similar to the convention al hybrids, but LRS matured substantially before the conventional hybrids. The LRS hybrid required fewer corn heat units to reach flowering and maturi ty and had more time for grain filling than the conventional hybrids. There fore, LRS hybrids show promise for production in short season areas where m aize cultivation is not economical due to shortness of growing season.