Coupling effects of water and nitrogen on yield, quality and water use of potato with drip irrigation under plastic film mulch

Abstract: In order to find out the best combination of water and nitrogen in the production of potato and to achieve the goal of saving water and fertilizer and maintaining high yield and good quality, we carried out a field experiment. The experiment was conducted to study the coupling effects of water and nitrogen on potato yield, quality and water use efficiency under drip irrigation with plastic film mulch in an arid area of Northwest China. There were ten treatments, including two soil wetting proportion levels (P1-40%, P2-70%) and five nitrogen levels (N1-90 kg/hm2, N2-135 kg/hm2, N3-180 kg/hm2, N4-225 kg/hm2, N5-270 kg/hm2). The results indicated that the weight of potato tuber, starch content of tuber and vitamin C content of tuber showed the parabolic changing tendency with the rise of nitrogen application rate for the same water level. Protein content of potato tuber ascended with the rise of nitrogen application rate. All of above showed the significant difference in different treatments. Potato tuber quality of P2 soil wetting proportion treatments was higher than that of P1 soil wetting proportion treatments with the same nitrogen amount. Yield, evapotranspiration and water use efficiency of potato showed the parabolic changing tendency with the rise of nitrogen application rate for the same water. Tuber yield of P2 soil wetting proportion treatments were 5% higher than those of P1 soil wetting proportion treatments. The yield showed the significant difference in different treatments. Evapotranspiration of the P2 soil wetting proportion treatments were 11% higher than those of P1 soil wetting proportion treatments. Water use efficiency of P1 soil wetting proportion treatments were 5.4% higher than those of P2 soil wetting proportion treatments. The tuber weight per plant and vitamin C content of potato tuber of P2N3 treatment and the starch content of tuber of P2N2 treatment had the best performance. The protein content of potato tuber of P1N5 treatment was the highest. Considering the quality indicators of the potato tuber, the quality of potato tuber of P2N3 treatment had the best performance. Treatment P2N2 had the highest yield in all treatments, amounting to 54 187 kg/hm2. Treatment P1N2 had the highest water use efficiency of 12.86 kg/m3. In consideration of the comprehensive performance of the yield, tuber quality and water use efficiency, treatment P2N3 are recommended as the best combination of water and nitrogen in the production of potato under drip irrigation with plastic film mulch in such an arid area of Northwest China.