Effects of N, P, K on Yield and Quality of Jujube in the Loess Hilly Region and Its Fertilization Model

The aim of this study is to explore the optimal N, P and K fertilization model suitable for pear-jujube in the mountain of northern Shaanxi in 2016 years. This experiment use 3-factor, saturated optimal design for quadratic fertilization scheme. The effects of different fertilization treatments on the yield and quality of pear-jujube were studied through field experiments. And comprehensive evaluation based on the quality of pear-jujube. The results showed that N1P3K3 has the highest yield, which is 48% higher than the control (CK). The effect of nitrogen, phosphorus, and potassium on yield is potassium fertilizer (positive effect)> phosphate fertilizer (positive effect)> nitrogen fertilizer (negative effect). Phosphate and potassium fertilizers have significant effects on increasing the content of soluble solids. Application of potassium fertilizer alone can significantly increase the content of reduced Vitamins c. The combined application of nitrogen, phosphorus, and potassium reduced the content of reduced Vitamins c. N3P3K1 treatment can significantly increase the total sugar content in fruits. Single application of phosphate and potassium increases the content of organic acids in fruits. Other fertilization treatments have significant effects on reducing the content of organic acids in fruits. The sugar-acid ratio of N3P3K1 is significantly higher than CK, which had an important effect on improving the taste. A high amount of potassium fertilizer has a significant effect on increasing the total flavonoid content in fruits. The interaction of nitrogen and phosphorus will reduce the total flavonoid content. The effect of nitrogen, phosphorus, and potassium on quality is potassium (positive effect)> nitrogen (positive effect)> phosphate (positive effect). Comprehensive analysis, the optimal fertilization amount when the target yield is 23000 [~] 27000 kg{middle dot}hm-2 and the quality score is above 85 is nitrogen (N) 406.93 [~] 499.31 kg{middle dot}hm-2, phosphorus (P2O5) 203.94 [~] 297.08 kg{middle dot}hm-2, and potassium (K2O) 285.47 [~] 322.82 kg{middle dot}hm-2.