Responses of maize hybrids with contrasting maturity to planting date in Northeast China.

Maize sowing in semi-humid region of Jilin province is often delayed beyond the optimum planting time window because of soil water stress typically occurring before or during the planting season. Research was conducted at Lishu city, in Jilin province from 2009 through 2010 to determine the responses of maize hybrids with contrasting maturity to planting date. Three popular hybrids with contrasting different maturity, short-season hybrid Jidan27, mid-season hybrid Xianyu335, and full-season hybrid Zhengdan958 were planted in early May and mid-May and thinned to populations of 67,500 plants ha. The results showed that durations from emergence to silking stage for all the hybrids consistently shortened as the planting delayed, but interaction effects of hybrids, planting date and year existed for the duration of silking to physiological maturity stage. The longer maturity hybrid usually had grain yield advantage over earlier maturity hybrid when planting at early May, but the earlier maturity hybrid often showed a greater yield than longer maturity hybrid when planting was delayed. The highest yield occurred at the treatment combination of the mid-season hybrid and delayed planting date, and the shorter season hybrid typically showed stable and higher grain yield across planting dates. Changes in grain volume per unit of land area among hybrids and planting date treatment combination were consistent with the changes in grain yields, indicating that the yield is determined usually by the sink capacity. Further research is needed to evaluate the effects of hybrids maturity and planting date on maize under different planting densities.