RELATIONSHIPS AMONG HYBRID MATURITY, ENVIRONMENT, DRY MATTER YIELD AND MOISTURE CONTENT OF WHOLE-PLANT CORN

Abstract

Seven field experiments were conducted in 1975 and 1976 to investigate, under Ontario conditions, the influence of environment and hybrid maturity-by-environment interactions on (1) percent whole-plant and grain moisture at the time of maximization of whole-plant dry matter (DM) yield, and (2) the degree of coincidence of the dates of attainment of maximum whole-plant and grain DM yields. Each experiment involved three hybrids of each of three maturity classes which were harvested periodically during the maturation period. Quadratic regression equations were computed between whole-plant DM yield, percent whole-plant moisture, percent grain moisture, and days after July 31, and from these, estimates were made of maximum yields, dates of attainment of these maxima, and of percent whole-plant and grain DM on these dates of maximization. With the exception of one experiment which was affected by drought stress, whole-plant DM yield tended to increase with seasonal corn heat unit (CHU) accumulation (i.e., CHU from planting to first frost) across the seven experiments, and with increases in the CHU-maturity rating of the various hybrids. Percent whole-plant moisture at which forage DM maximized decreased as seasonal CHU accumulation increased and ranged from 58 to 69%. Percent grain moisture on date of maximization of whole-plant DM was affected by both seasonal CHU accumulation and hybrid maturity rating, and ranged from 25% for low-CHU hybrids in a high-CHU environment to 52% for the converse. Percent whole-plant moisture relative to percent grain moisture on date of attainment of maximum forage DM decreased at a rate of about 1% for each 100 CHU increase in hybrid maturity rating. Because of the large uncertainty in prediction of dates of attainment of maximum whole-plant versus grain DM yield, we were unable to answer with confidence the question as to whether the temporal difference between the two varied with seasonal CHU accumulation or hybrid maturity rating.Key words: Zea mays, forage, yield, moisture content