Effects of drip fertigation around root zone on yield and quality of red jujube and utilization of nitrogen, phosphorus and potassium in Xinjiang

Abstract: Reasonable selection of drip fertigation technique is the key to achieve the effects of water-saving and fertilizer reduction in the intensive orchards. In this study, the influences of surface drip fertigation method (SD) and in-hole around rootzone drip fertigation method (RD) on the growth, fruit quality and the uptake of nitrogen (N), phosphorus (P) and potassium (K) in Xinjiang red jujube were investigated in the Akasu, southern Xinjiang area. The Chinese jujube was planted since 1999. 3 plots were prepared. In each plot, the 2 treatments were used. In the treatment of SD, the drip line was placed both sides of jujube tree. In the treatment of RD, 1 lateral pipe without emitters in diameter of 8 cm was placed on the soil surface for a line of jujube tree. Around each tree, 6 holes in diameter of 10 cm and depth of 35 cm were drilled for placement of catheter with emitters. The holes were filled with cottonseed cake to hold the catheter. The emitter had flow rate of 3.75 L/h. For each replicate of treatment, 10 jujube trees were included. The irrigation amount and fertilizer application rate were same for the 2 treatments. In 2011 and 2012, the yield and quality of jujube were determined. In 2012, the cumulative N, P and K content in the jujube trees were also determined. The results showed that the 2-year average yield of jujube fruit in the RD treatment significantly increased by 6.9% compared to the SD treatment. Meanwhile, the 2-year average weight of single dry fruit was 5.04 g in the RD treatment, which was 8.4% higher than that in the SD treatment. The influence of irrigation method on quality of jujube was similar except for the ratio of sugar to acid content. In 2011, the total sugar and reducing sugar content of the RD treatment were 5.6% and 40.9% higher than those of the SD treatment; The crude fat and the ratio of sugar content to acid content in the RD treatment was significantly higher than that in the SD; The other quality index was similar in the both treatments. In 2012, the ratio of sugar content to acid content was not significantly different between the both treatments and the influence of treatments on the other jujube quality index followed the same way with that in 2011. In general, the RD could increase jujube yield and quality. Compared to the SD treatment, the RD treatment increased the contents of N, P, and K in the leaf of jujube tree in 2011 by 6.7%, 33.6% and 7.3%, respectively, while it only increased the contents of N and P in the leaf in 2012. In 2011 and 2012, the significant higher content of P in shoots and roots of the treatment of RD was observed than that in the treatment of SD. In the jujube fruits, the P and K content of the treatment of RD was significantly higher than those in the SD treatment by 41.0% and 13.6% in 2011 and 46.2% and 12.9% in 2012 (P<0.05). In the harvest stage of 2012, the biomass of root and fruit were significantly higher by 46.7% and 8.0% in the RD treatment than in the SD treatment (P<0.05). In the meantime, the cumulative of P in the jujube tree was significantly higher in the RD treatment than in the SD treatment. The total P accumulated content was 33.72 g/plant in the RD treatment and 21.23 g/plant in the SD treatment. Economic benefit analysis on jujube orchard under different irrigation methods showed that, although the cost increased by 1 950 RMB/hm2 with the RD treatment compared to the SD treatment, the jujube output increased by 3 750 RMB/hm2. Therefore, the management practices of RD treatment significantly increase the biomass in root system, fruit yield, the nutrient content of jujube tree, and the utilization efficiency of fertilizer. This study provide an effective irrigation method for orchard so as to improve yield and save water.