Variations in the yield and moisture content of ears of forage corn varieties with different relative maturity

Corn production for concentrated feed is increasing in Japan, and cultivation techniques are necessary to obtain higher yields. To expand the corn production for concentrated feed in the Kanto region of Japan, corn varieties based on their earliness was evaluated. Changes in ear yield and moisture content were compared among 12 commercial varieties, which were divided into three groups based on their relative maturity (RM): extremely early (RM 95–100), early (RM 113–115) and medium (RM 125). The varieties were sown at three different times (late April, middle May and late May) for three cultivation years. Our experiment found that the ear dry weights of both early and medium groups were higher than that of the extremely early group. Ear moisture of the extremely early group decreased rapidly and reached 35% as a standard for harvesting time we defined, at 60 days after silking, while that of the early group reached 35% at 70 days after silking, and that of the medium group did not reach 35% during the experimental period. Late sowing decreased ear dry weight and delayed ear moisture decreasing. The extremely early group had the advantage of early harvesting at 60 days after silking, and the early group obtained a higher yield than the extremely early group at the harvesting at 70 days after silking. These results suggest that extremely early and early groups are suitable for corn production for concentrated feed in the Kanto region.