关键词: 滴灌棉花, 磷肥后移, 减氮, 磷肥利用率, 产量

Abstract:

【Objective】 This study aimed to explore the regulation effect of phosphorus fertilizer postponement on the maintenance of high yield of drip-irrigated cotton under the condition of nitrogen reduction, and to define the consequence of phosphorus fertilizer postponement on the utilization efficiency of cotton phosphorus fertilizer under the condition of nitrogen reduction.【Method】 A 2-year field experiment (2022-2023) was performed in the experimental ground of Shihezi University, which used Zhongmian 109 as test material. A total of six experimental treatments were set up: conventional nitrogen application (N_ck: 400 kg·hm^-2), 50% phosphorus fertilizer management treatment at the squaring stage and 50% at the flowering and boll setting stage (total phosphorus fertilizer application rate 105 kg·hm^-2, N_ckP3), and nitrogen reduction conditions (25% nitrogen reduction, Nr: No phosphorus fertilizer was applied at 300 kg·hm^-2 (P0), 100% phosphorus was applied at the squaring stage (P1, the total application rate of phosphorus fertilizer was 105 kg·hm^-2, the same below), 75% at the squaring stage + 25% at the flowering and boll setting stage (P2), 50% each at the squaring stage and the flowering and boll setting stage (P3), 25% at the squaring stage + 75% at the flowering and boll setting stage (P4) They are respectively denoted as N_ckP3, N_rP0, N_rP1, N_rP2, N_rP3 and N_rP4.【Result】 (1) Compared with N_ckP3, only N_rP3 treatment had no significant difference in seed cotton yield; under the nitrogen reduction condition, the seed cotton yield udner other treatments increased significantly compared with P0, and the increase under P3 treatment was the largest, reaching 31.0% (mainly due to the significant increase of seed cotton yield in the middle and upper branches). (2) Compared with N_ckP3, only the N_rP3 treatment showed no significant differences in the biomass of each organ and the accumulation of phosphorus in cotton. Under reduced nitrogen, compared with P0, the postponed phosphate fertilizer increases the biomass of reproductive organs in the middle and upper fruit branches of cotton and the proportion of phosphate distribution, the increase was the greatest under the P3 treatment, which were 11.0%, 21.7% and 79.6%, 72.0% respectively, and significantly increased the biomass accumulation of cotton and promoted the phosphorus absorption and utilization. In addition, only N_rP3 treatment had a higher phosphorus utilization rate than N_ckP3, with an increase of 15.8%. (3) The yield of seed cotton and the utilization rate of phosphorus fertilizer were positive correlated with the average accumulation rate VT of aboveground and reproductive organs biomass during the rapid accumulation period. The former was also significantly positive correlated with the maximum accumulation rate Vm of reproductive organs biomass, and the latter was positive correlated with the maximum accumulation rate Vm of reproductive organs phosphorus.【Conclusion】 Under nitrogen reduction conditions, N_rP3 treatment (the proportion of the postponed phosphorus fertilizer was 50%) can enhance the transport and distribution of biomass to the reproductive organs of the middle and upper fruit branches of cotton, promote the accumulation and distribution of phosphorus from the middle and upper fruit branches to the reproductive organs, improve the utilization rate of phosphorus fertilizer, and ultimately achieved the goal of reducing nitrogen in cotton without reducing yield.

Key words: drip-irrigated cotton, phosphate fertilizer postponement, nitrogen reduction, utilization rate of phosphate fertilizer, yield