RELATIONSHIPS AMONG WHOLE-PLANT MOISTURE, GRAIN MOISTURE, DRY MATTER YIELD, AND QUALITY OF WHOLE-PLANT CORN SILAGE

Abstract

Identical experiments were conducted at the Elora Research Station, near Guelph, Ontario in 1970 and 1971 with the objective of determining the relationships among whole-plant dry matter (DM) yield, whole-plant moisture content, and grain moisture content of corn (Zea mays L.) during the later part of the growing season. Each experiment involved eight commercial hybrids representative of the range in maturity, endosperm type, lodging resistance, and grain yield potential of corn hybrids grown commercially in central Ontario. The hybrids were sampled at weekly intervals over an 8-wk period beginning approximately 1 September; the sampled plants were divided into their leaf, stalk, husk, ear and grain components and oven-dried. Fresh and dry weights were used to calculate dry matter (DM) yields and "at harvest" moisture contents of the various components, and of the entire plant. Averaged across the eight hybrids, maximum DM yield was attained at whole-plant moisture content of 66–70%, and a grain moisture content of 45–50%. Among hybrids, 66% whole-plant moisture corresponded to a range in grain moisture content from 41 to 47%. Two additional experiments were grown also at Elora in 1970 and 1971 to evaluate the effects of harvest date on the DM yield and in vitro digestibility of corn plants and their component plant parts. Each experiment involved four representative commercial hybrids which were sampled at four equal time intervals during the month of September, and divided into grain, cob, husks (including shank) and stover (including leaves, leaf sheaths, stalks and tassels) for dry weight and in vitro digestibility measurement. Whole-plant DM digestibility was essentially constant over a range of whole-plant moisture from 76 to 56% in 1970, and from 76 to 64% in 1971. The consistency of whole-plant digestibility was the result of compensating changes in component yield and digestibility. A decrease in the digestibility of the stover, husks and cob with delayed harvest was compensated for by an increase in the proportion of grain in the whole-plant yield.