EFFECTS OF PLANT DENSITY ON THE YIELD, MATURITY AND GRAIN CONTENT OF WHOLE-PLANT MAIZE

Abstract

To study the effect of increases in plant density on the dry matter (DM) yield, percentage grain and percentage DM content of whole-plant maize (Zea mays L.), 12 tests were established over a 3-yr period in Central and Southern Ontario. Each test involved three adapted hybrids grown at 50 000, 63 000 and 75 000 plants/ha in 1976, and at these three densities plus 92 000 plants/ha in 1977 and 1978. No hybrid-by-density interaction for DM yield occurred in any test, and the density response was similar for most tests. Maximum DM yield was generally attained once density increased to 63 000 plant/ha. Plant population had a negligible effect on the grain percentage of DM content of forage up to 75 000 plants/ha. Optimum density for DM yield was much lower than expected, given the small stature (i.e., leaf area/plant) of adapted hybrids grown in most of Ontario.