冬小麦从小麦出苗到拔节前,田块中存在的苗弱、苗小、黄叶、黄心、黄蘖等都属于黄苗。1.发生原因(1)整地质量不好,明暗坷垃多,土壤悬松,扎根不实,导致麦苗缩心、黄叶。(2)施用未充分腐熟的基肥,或种肥施用过多,使种子或幼苗接触肥料、烧伤或死亡。(3)低温、土壤干旱、大风和霜冻等气象因素所造成的,这种黄叶出现时间往往和天气变化紧密联系在一起,范围 Before emergence of winter wheat from wheat to jointing, there are seedlings in the field weak, small seedlings, yellow leaves, yellow heart, yellow tiller, etc. belong to yellow seedlings. 1. The reasons (1) site preparation is not good quality, more bumpy soil, soil loosening, rooted in reality, leading wheat seedling contraction, yellow leaves. (2) Application of underfull basal fertilizer, or excessive application of seed fertilizer, exposing seed or seedling to fertilizer, burns or death. (3) meteorological factors such as low temperature, soil drought, gale and frost are caused by the emergence time of yellow leaves and weather changes are often closely linked to the scope