Water Stress and Nitrogen Application Rates on Yield and Nitrogen Use Efficiency of Sweet Potato

Huang Shihao; Zhang Tingge; Qin Minghui; Song Chaoyu; Zhang Shuhai; Liu Qing; Fang Zengguo; Li Huan

doi:10.14083/j.issn.1001-4942.2025.05.013

Abstract：Although sweet potato is a drought-tolerant and barren-tolerant crop,seasonal drought stress and unreasonable application of nitrogen fertilizer are still the main factors restricting yield of sweet potato in northern China.In this study,under the condition of artificial water control,three irrigation amounts(normal water supply,mild water stress and moderate water stress with corresponding soil relative water content of(70±5)%,(55±5)%and(40±5)%(referred to as W1,W2,W3)and three nitrogen application rates(60,120,180 kg/hm-2,referred to as N1,N2,N3)were set and combined into 9 treatments to study the effects of different water and nitrogen conditions on dry matter accumulation,photosynthetic and fluorescence physiological characteristics of leaves,yield and nitrogen use efficiency of sweet potato.The results showed that the root dry weight,nitrogen accumulation,tuber number per plant and yield of sweet potato decreased significantly with the decrease of irrigation amount at each growth stage,and increased firstly and then de-creased with the increase of nitrogen application rate(under W3 condition,they decreased significantly with the increase of nitrogen application rate).Under mild water stress(W2),the net photosynthetic rate,stomatal conductance,transpiration rate and nitrogen use efficiency of N2 treatment were significantly higher than those of the other two nitrogen application levels,indicating that appropriate nitrogen application could improve the drought resistance of sweet potato and had a certain compensation effects on the main physiological processes and yield formation.Under moderate water stress(W3),the physiological and yield indexes of sweet potato de-creased significantly with the increase of nitrogen application rate,indicating that excessive nitrogen application would aggravate water stress,reduce drought resistance and adversely affect yield of sweet potato.These results could provide a theoretical basis for water and nitrogen management in the actual production of sweet potato.