Dry Matter Accumulation and Silage Moisture Changes after Silking in Leafy and Dual‐Purpose Corn Hybrids

Abstract

The increasing use of new silage‐specific corn (Zea mays L.) hybrids, including Leafy types, has created a need for more information on the decision of hybrid choice and time of harvest. A field experiment including dual‐purpose and Leafy silage‐specific hybrids was conducted for 4 yr (1999–2002) at Ottawa, ON, Canada. Specific objectives were to determine (i) differences in whole plant moisture and dry matter (DM) accumulation after silking, and (ii) the optimum harvest windows of the contrasting corn types. Samples of whole plant moisture and DM accumulation were taken and analyzed at 3‐ to 7‐d intervals from approximately 3 wk after silking to physiological maturity. Our results showed that the rate of decline in silage moisture content varied among the years and hybrid types. On average, 85% of total DM accumulation was achieved when the whole plant moisture was about 65% for all hybrids. Compared to dual‐purpose hybrids, the whole plant moisture of Leafy silage‐specific hybrids declined more slowly, especially for hybrid ‘Mycogen TMF94’. We concluded that 65% whole plant moisture normally corresponded to the 50% kernel milk line (ML), and occurred between 50 and 60 d after silking under the northeast climate conditions. Silage‐specific hybrids had larger windows for harvest than dual‐purpose hybrids. However, ML progression was irregular for Leafy hybrids and changed more rapidly for dual‐purpose hybrids. Under extreme weather conditions, kernel ML does not correspond to silage moisture content in the same way as under normal conditions, therefore, silage harvest should be based on actual moisture content.