Effects of Nitrogen Fertilizer on Dry Matter Accumulation, Distribution and Root Yield of Sweet Potato Cultivars with Different Nitrogen Tolerance

Sun Meidi; Duan Wenxue; Zhang Haiyan; Xie Beitao; Wang Baoqing; Wang Qingmei; Zhang Liming

doi:10.14083/j.issn.1001-4942.2017.03.015

Abstract：A field experiment was conducted using the long-vine sweet potato cultivar Jishu 26 and the short-vine sweet potato cultivar Xushu 32 as materials.Three levels of nitrogen fertilizer of 0,120 and 240 kg/hm2 were designed,which were defined as N0,N1 and N2 treatment,respectively.The dry matter accumulation,distribution and root yield were investigated.The results showed that the two cultivars exhibited different nitrogen resistance.The root yield of Jishu 26 was significantly higher than that of Xushu 32 under N0 treatment,whereas the root yield showed opposite trend under N1 and N2 treatment.The yield reduction range of Jishu 26 was significantly higher than that of Xushu 32 under nitrogen application treatment.With the increase of nitrogen rate,the dry weight at above-ground and T/R ratio in both cultivars significantly increased,while the root dry weight significantly decreased.Nitrogen fertilizer could promote the dry matter distribution in stem and leaves of lateral branch at early growth stage,in branch growth point at middle growth stage and in all parts of lateral branch at late growth stage,respectively.Compared with the cultivar Xushu 32,Jishu 26 showed higher dry matter distribution in growth point of main stem and in leaves of lateral branch under higher nitrogen levels.The ratio of dry matter distribution in tuber roots increased with the progress of development.With the increase of nitrogen rate,the ratio of dry matter distribution in tuber roots significantly decreased.The cultivar Xushu 32 exhibited higher dry matter distribution in tuber roots under higher nitrogen levels.Nitrogen application in this research promoted the dry matter distribution in lateral branches and reduced the dry matter distribution in tuber roots,which was not beneficial for improving tuber root yield.In soils with high fertility,cultivars with higher nitrogen resistance should be considered.