玉米是需水较多的作物,对水分代谢的临界期在开花前8￣10d开始的约30d之内。半干旱地区旱作地膜玉米的主要障碍因子是“干旱缺水”,降水高峰期在小暑至立秋的约30d时间,拔节后的水分供应唯一靠自然降水。因此,确定半干旱地区旱作地膜玉米的最佳播期,应以“降水高峰期”因子为主要指标,即应用“调水说”播期理论。 Corn is a crop requiring more water, and the critical period for water metabolism is within about 30 days before 8-10 days of flowering. The main obstacle factor of dry film mulching corn in semi-arid area is “drought and water shortage.” During the peak period of precipitation, about 30 days after the onset of the summer and the beginning of autumn, the water supply after jointing only depends on natural precipitation. Therefore, to determine the best sowing date for maize mulched in semi-arid area, the “precipitation peak” factor should be taken as the main index, that is, the “sowing date” sowing date should be applied.