Effects Of Water Supply And Nitrogen Forms On Nitrogen Uptake And Utilization,Yield And Quality Of Potato

To clarify the effects of nitrogen forms on potato growth,physiology,biochemistry,nitrogen uptake and utilization,yield,and tuber nutritional quality under different water supply.In this experiment,’Chunshu No.4’potato was used as the experimental material,and a two-factor randomized block design was used.Three levels of water content were set,namely,70%<W₁≤80%,60%<W₂≤70%,and 50%<W₃≤60%.The nitrogen form ratio was NO₃^-:NH₄⁺=100:0（N₁）,NO₃^-:NH₄⁺=75:25（N₂）,NO₃^-:NH₄⁺=50:50（N₃）,NO₃^-:NH₄⁺=25:75（N₄）,and NO₃^-:NH₄⁺=0:100（N₅）,with a total of 15 treatments.The effects of nitrogen forms on potato physiological characteristics,yield,tuber nutritional quality,and nitrogen uptake,utilization,and distribution were analyzed under different water supplies.It is expected to provide theoretical basis for water-saving irrigation and nitrogen efficient management of potatoes in Northeast China.The main results are as follows:（1）Under different water supply,the mixed application of nitrate and ammonium can promote the root activity of potato,increase the accumulation of chlorophyll content and soluble sugar and other nutrients in leaves,and improve the plant’s own immunity and defense invasion function;among them,N₄ treatment was the best,plant height,stem diameter,leaf area,SOD,POD,CAT activity,GPT,GOT activity were significantly higher than other treatments;followed by N₃ treatment;N₁ treatment was the worst.（2）The dry matter and nitrogen accumulation in each growth period showed W₁>W₂>W₃,and peaked at 100 days after emergence.the dry matter and nitrogen accumulation rate of potato showed mixed application of ammonium nitrate>ammonium nitrogen>nitrate nitrogen.The dry matter and nitrogen accumulation rate of W₁N₄ was the highest,which was 4.79 g·plant^-1·d^-1 and0.2032 g·plant^-1·d^-1.The accumulation of nitrogen in potato conformed to the Logistic equation,and the nitrogen accumulation rate of each treatment showed a single peak curve.The application of ammonium nitrogen fertilizer can delay the time of the maximum accumulation rate of nitrogen,and the maximum accumulation rate of each treatment occurs between 57d～65d,among which the maximum accumulation rate of W₁N₄ nitrogen appears the latest,64.1 days.It shows that the increase of ammonium nitrogen fertilizer increases the rate of nitrogen accumulation and prolongs the accumulation time,thus promoting the increase of nitrogen accumulation.（3）The maximum rate of dry matter and nitrogen accumulation of potato was mixed application of ammonium nitrate>ammonium nitrogen>nitrate nitrogen.The dry matter and nitrogen accumulation rate of W₁N₄ was the highest,which was 4.79 g·p^-1·d^-1 and 0.2032 g·p^-1·d^-1,respectively.The results showed that the tuber weight per plant,tuber number per plant and yield were significantly positively correlated with nitrogen absorption efficiency under three water conditions.The correlation coefficients of W₁ were 0.758^**,0.955^**,0.955^**,W₂ were0.813^**,0.946^**,0.946^**,W₃ were 0.648^**,0.893^**,0.893^**.W₁N₄ had significant effects on improving nitrogen use efficiency,absorption efficiency and yield of potato,which were 76.98%,30.89%and 27.6 t·ha^-1,respectively.（4）The increase of water and ammonium nitrogen ratio could significantly increase the content of potato protein,soluble sugar,starch and VC,and reduce the accumulation of nitrate in tubers.The principal component analysis of potato tuber nutritional quality showed that the comprehensive score of W₁N₄ was the highest（2.2）,which was mainly reflected in its protein and starch content was significantly higher than other treatments.Followed by W₂N₄;W₃N₁ had the lowest score,which was due to the accumulation of nitrate content in tubers caused by single application of nitrate nitrogen.