YI Zifeng, DUAN Shaoguang, BIAN Chunsong, LU Xiaojing, LI Sen, QIN Junhong, LI Guangcun
Drought and improper nitrogen fertilizer application are significant issues affecting the green and high-quality development of the potato industry.Using the varieties‘Favorita'and‘Zhongshu No.18',we conducted a pot experiment under rain shelters to analyze the effects of different water and nitrogen management strategies on photosynthesis,nitrogen metabolism enzymes,dry matter accumulation and distribution,yield,and water and nitrogen use efficiency in potatoes.The results show that all photosynthetic indicators,whole-plant dry matter,yield,and water and nitrogen use efficiency were significantly influenced by water,nitrogen,and their interaction.The impact of nitrogen application rate was greater on‘Zhongshu No.18'than on ‘Favorita'.Photosynthetic characteristics,yield,and water use efficiency initially increased and then decreased with increasing nitrogen application rate,while nitrogen use efficiency decreased with increasing nitrogen application rate.Except for water use efficiency,all other indicators increased with increasing water levels.Whole-plant dry matter increased with higher water and nitrogen levels,but dry matter allocation to tubers increased with higher water levels and decreased with higher nitrogen levels.Nitrate reductase(NR)and glutamine synthetase(GS)activities were significantly affected by water and nitrogen,respectively,with NR activity being higher at moderate water levels and GS activity being higher at high nitrogen levels.Dry matter accumulation,net photosynthetic rate,number of tubers,and yield per plant showed extremely significant positive correlations in both varieties.Through equation fitting,the optimal nitrogen application rates for maximum yield under low,medium,and high water levels for‘Favorita'and‘Zhongshu No.18'were determined to be 7.55,9.95,and 11.66 g per plant and 8.67,10.09,and 12.83 g per plant,respectively.These findings provide a theoretical basis for efficient nitrogen management in different irrigation zones for potato cultivation.