Abstract:In order to explore the field resistance identification method of sweet potato (Ipomoea batatas) foot rot and to screen resistant germplasm, a total of 81 germplasms with resistance or other traits were identified after 1-3 years experiment, and the disease changes in different growth stages of sweet potato and the effects of different resistance grades on the yield loss rate of fresh sweet potato were analyzed. The results showed that among the 81 germplasms, 24 and 11 were highly resistant and resistant, respectively. From 90 to 120 d of growth stage, the disease changed obviously, especially the proportion of grade 4 disease of the susceptible species increased rapidly. There was a significant negative correlation between fresh potato yield and disease index (r= -0.978 1**), and the average yield loss rate of fresh potato increased by 19.35% for each resistance grade decrease. At 120 d of growth stage, there was a significant positive correlation between incidence and disease index (r= 0.992 5**). Therefore, in addition to disease index, incidence could also be used as an index to identify resistance to foot rot of sweet potato.
