在育苗过程中，往往会遇到下面几种不正常现象： 　　一、不出苗 　　播种后不出苗的原因是：种子存放年限过久或保存不当而失去发芽能力；有的虽然发芽，但生长势弱，不能顶出土表就死掉了；床土温度过低时，种子不能发芽；覆土太厚时，芽子拱不出地表；底水不足，覆土太薄时 In the process of nursery, often encounter the following irregularities: First, do not seedling emergence after emergence is not due to: long storage of seeds or improper storage and lose their ability to germinate; some sprout, but growing weak , Can not top the surface of the table to die out; bed soil temperature is too low, the seeds can not germinate; overburden too thick, buds arches not surface; underdeveloped, overburden too thin