近年来,对高产玉米杂交种的选育,就春播玉米说,一般认为生育期较长,有利于植株营养生长和果穗的分化灌浆,选育单株大穗型杂交种容易获得高产。而夏播玉米因生育期较短,生育期间所处的自然条件较差,不易孕育大穗,选育果穗中等大小,结实性良好、双穗率较高的杂交种,通过提高单株生产力达到丰产,并认为双穗率高的组合,不易空秆,在密植情况下可能较单穗型产量高而稳定。我省江淮丘陵地区位于长江、淮河之间,属北亚热带湿润气候,气温高,降水 In recent years, the selection of high-yielding maize hybrids for spring-sowed maize is generally considered to have a long growing period, which is conducive to vegetative growth and differentiation and filling of ear. It is easy to obtain high-yielding single-ear hybrids. However, the summer sowing maize due to shorter growth period, poor natural conditions during growth period, not easy to breed big spike, middle ear size breeding, good seed setting, high ear hybrid rate, by increasing the productivity per plant High yield, and that the combination of high double-spike, not easy to empty stalk, in the case of close planting may be more than single-spike yield high and stable. Jianghuai hilly area in our province is located between the Yangtze River and the Huaihe River. It belongs to the subtropical humid climate, with high temperature and precipitation