根据我国甘薯病毒病传播的途径和特点,为防止病毒病的回传,一般要求在繁殖脱毒甘薯原原种时盖40目防虫网。而甘薯在网室内生长,光照弱,通透性差,昼夜温差小,往往造成茎叶徒长。茎叶徒长,群体过大,叶面积指数超过4,结果空株率高,产量低,一般鲜产仅500～750ｋｇ/667ｍ2。为了加大 According to the pathways and characteristics of the transmission of sweet potato virus in China, in order to prevent the return of virus disease, it is generally required to cover the 40-mesh insect-proof net when breeding the original virus of sweet potato. The sweet potato growth in the net room, weak light, poor permeability, small temperature difference between day and night, tend to cause stems and lengthens. Stems and leaves are long, the group is too large, the leaf area index exceeds 4, the result empty plant rate, low yield, the general fresh produce only 500 ~ 750kg / 667m2. To increase