Abstract:

On the basis of the same level fertilizer application，field experiments were conducted to study the effects of nitrogen, phosphorus and potassium by stages on yield and quality of sweetpotato in the town of Yuanyang village community Caijia 2 and the town of Shifou village community Caijia 3 of Jiangjin in Chongqing. The results showed that compared with conventional fertilization, application of nitrogen and potassium as well as nitrogen, phosphorus and potassium fertilizer by stages were effective to improve the yield of sweetpotato tubers. Among them, tubers yield were increased by 6.8% to 29.5 % and 7.7 % to 44.6% respectively in Yuanyang and Shifou. Vc content of sweetpotatos were in order to increase in main of the fractional fertilization treatments. The increase range was from 4.8% to 29.9% in Yuanyang and was from 0.7% to7.3% in Shifou. The contents of starch and total potassium in sweetpotatos were in order to decrease in all fertilization by stages treatments. The decrease range was 2.4% to 5.5% and 12.3%~69.5% in Yuanyang, 2.4% to 17.4% and 0.9%~22.8% in Shifou respectively. Changes of soluble sugar, crude protein and phosphorus in sweetpotatos were inconsistent in two experiments. Therefore, split application nitrogen, phosphorus and potassium can improve the yield and some quality of sweetpotato.