[Effects of the frequency and amount of drip irrigation on yield, tuber quality and water use efficiency of potato in sandy soil of Yulin, northern Shaanxi, China].

Reasonable irrigation is still lacking for potato production in the sandy areas of Yulin, northern Shaanxi Province. To solve this problem, field drip fertigation was conducted to examine the growth, yield and quality of potato during the whole growing season. We further analyzed the responses of these indices to different irrigation frequencies and amounts. There were three irrigation frequencies (d), i.e. 4 (D1), 8 (D2) and 10 (D3), and three irrigation amounts, i.e. 60%ETc (W1), 80%ETc(W2) and 100%ETc(W3), where ETc was the crop water requirement, resulting in a total of nine treatments. Under the same irrigation frequency, plant height, leaf area index, dry matter, tuber yield and economic benefits of W3 were higher than those of W1 and W2. W1 had the highest irrigation water use efficiency (IWUE), while water use efficiency was not significantly affected by irrigation amount. The average tuber yield of W3 was 43442 kg.hm(-2), which was 23.3% and 11.6% higher than that of W1 and W2, respectively. The net income of W3 was 23492 yuan.hm(-2), which was 40.4% and 18.7% higher than that of W1 and W2, respectively. Tubers from W3 had the highest starch and vitamin C contents but the lowest reducing sugar content, which were 14.4%, 18.54 mg.(100 g)(-1) FW and 0.7%, respectively. At the same irrigation amount, tuber yield, IWUE, starch and vitamin C contents of D1 were the highest, but the reducing sugar content was the lowest at the low and medium irrigation amounts. At the high irrigation amount, D2 had the highest tuber yield, IWUE, net income, starch and vitamin C contents but the lowest reducing sugar content, which were 46572 kg.hm(-2), 23.04 kg.m(-3), 26,622 yuan.hm(-2),14.6%, 19.53 mg.(100 g)(-1) FW and 0.7%, respectively. Based on the interacting effects of drip irrigation frequency and amount, both yield and quality of D2W3 reached the maximum. Results from the principal component analysis showed that D2W3 had the highest score. D2W3(8 d, 100%ETc) had the greatest yield and quality and relatively higher water use efficiency, which was thus considered as the optimal combination of drip irrigation frequency and amount. The results could provide a scientific basis for the drip irrigation scheduling design for high-yield, high-efficiency and high-quality potato production in the sandy areas of Yulin, northern Shaanxi.