试验目的玉米杂交种子的收获时期一般集中在9~11月份,每年各种子企业大都在11月份开始对种子清选、包衣、包装。从11月份至第2年度5月份都是种子的加工时间,这个生产周期历时近半年。各企业为了有效降低本年度剩余成品库存,会分批对种子进行包装,于是会出现相同种子在不同时期完成包衣的情况。近年有些农户反映相同的品种在相同年份,因为购买种子时间不同,出苗情况差别较大,故试验选择不同时间对种子完成包衣, Experimental purposes Corn hybrid seeds are generally concentrated in the harvest period from September to November, most of the seed companies each year in November began to seed clearance, coating, packaging. From November to the second year in May are seed processing time, the production cycle lasted nearly six months. In order to effectively reduce the inventories of the remaining finished product for the current year, the enterprises will package the seeds in batches and the same seeds will be coated at different times. In recent years, some farmers reflect the same species in the same year, because the time to buy different seeds, the emergence of a great difference, so the test choose different time to complete the seed coating,