Response of Vine Overgrowth in Sweet Potato to Nitrogen Fertilizer and Its Characteristic Indexes

Duan Wenxue; Zhang Haiyan; Xie Beitao; Wang Baoqing; Zhang Liming

doi:10.14083/j.issn.1001-4942.2018.02.007

Abstract：We studied the nitrogen tolerance and vine overgrowth of sweet potato varieties Jishu 18,Violet,Jishu 25,Xushu 32 and Guangshu 87 treated with no nitrogen (NO),120 kg/hm2 (N1) and 240 kg/hm2 (N2) of pure nitrogen treatments under field conditions.The growth indexes of stems and leaves aboveground were subjected to multivariate statistical analysis,and the field characteristic indicators of vine overgrowth of sweet potatoes were confirmed.The results revealed that different varieties had different levels of nitrogen tolerance and vine overgrowth.Compared with the other varieties,Xushu 32 and Guangshu 87 were more resistant to nitrogen evidenced by their higher yield and lower vine overgrowth degree under high nitrogen levels.Jishu 25 and Jishu 18 exhibited moderate nitrogen tolerance,whereas Violet demonstrated extreme sensitivity to nitrogen with high overgrowth degree.The correlation,principal component,and gray correlation analyses of the field indicators showed that the third internode length and the petiole length of the third unfolded leaf of the main stem on the 50th day after planting could effectively reflect the fresh weight aboveground at harvest stage.The first and second internode lengths and the petiole length of the third unfolded leaf of the main stem could reflect the T/R value at harvest stage.The petiole length of the third unfolded leaf of the main stem on the 50th day after planting could be used as a characteristic indicator of vine overgrwoth.This study provided references for screening fertilizer-tolerant varieties and judging the suitable time for controlling the vine over-growth of sweet potato.