关键词: 棉花, 减量施氮, 磷钾运筹, 产量, 叶面积指数, 滴灌, 北疆

Abstract:

【Objective】The aim of this study was to clarify the response of reduced nitrogen (N) application with different phosphorus (P) and potassium (K) managements (PK-M) on drip-irrigated cotton growth, dry matter accumulation and yield formation in Northern Xinjiang, so as to provide a theroe base for reduced N application with cost saving. 【Method】Field experiments were conducted by using Lumianyan 24 under four N application rates (506, 402.5, 299 and 195.5 kg·hm^-2 designated as N1, N2, N3 and N4, respectively), and four different PK-Ms during squaring stage and bloom-bolling stage (100%+0, 25%+75%, 50%+50% and 75%+25% designated as PK-M1, PK-M2, PK-M3 and PK-M4, respectively). The leaf area index (LAI), dry matter accumulation and distribution, reproductive organs dynamic changes and yield were assayed during experiment period. 【Result】Under the same PK-M treatment, the K’ value of LAI’s Logistic model showed a trend of first increasing and then decreasing with the decrease of nitrogen application rate; the K’ value under N3 was 5.1%-16.5% higher than that under N2, and which in the fast accumulation period in initiated (t₁) and terminated (t₂) days were the latest under N3; which in the duration of fast accumulation period (T) was the longest, and N3 was 2-12 days longer than N2. The growth characteristic value (GT) under N3 was the highest, followed by N2, and N3 was 5.2%-16.7% higher than that under N2. The dry matter accumulation in the early growth period was N1>N2>N3>N4 treatment, and in the late period was N2>N1>N3>N4 treatment. The number of reproductive organs was N2>N3>N1>N4 treatment during the growth period. The relative yield value under N2 was the highest, followed by N3 treatment, which under N2 was 3.6%-6.5% higher than that under N3. Under the same N application rate, the K’ value of LAI logistic model under PK-M3 was the highest and PK-M1 was the lowest, and PK-M3 was 20.5%-27.4% higher than PK-M1; the fast accumulation period in initiated (t1) (except in 2019) and terminated (t₂) days were both the latest under PK-M3. The growth characteristic value (GT) under PK-M3 was the highest, followed by PK-M2, and PK-M3 was 13.0-24.5% higher than PK-M2. The dry matter accumulation in the growth period was PK-M2>PK-M3>PK-M4>PK-M1 treatment, and it was PK-M3>PK-M2>PK-M4>PK-M1 treatment in the late growth period; the number of squares and bolls in the early growth period was PK-M4>PK-M3>PK-M1>PK-M2 treatment, while it was PK-M3>PK-M2>PK-M4>PK-M1 treatment in the late growth period; the relative yield value was the highest in PK-M3, which was 5.2%-18.2% higher than PK-Ms. Among all the treatments, the K’ value and GT value of the LAI Logistic model under N3PK-M3 was the largest, and T was the longest. The plant dry matter, relative yield value and the number of squares and bolls in the late period were second only to N2PK-M3, and the reproductive organs dry distribution ratio was higher than other treatments. Correlation analysis showed that LAI had a significant positive correlation with reproductive organ dry matter, plant dry matter and relative yield value at the late growth period, however, the number of reproductive organs, plant dry matter and reproductive organs were significant positive correlation with relative yield throughout the growth period. Among all treatments, the yield under N2PK-M3was the highest, followed by N3PK-M3, and the relative yield value in N3PK-M3 treatment was 1.5% lower than N2PK-M3 without significant difference. 【Conclusion】The N3PK-M3 could obtain higher yield by reducing 25% N application compared with the conventional N application rate of farmers, which might due to delaying the peak of LAI at the later growth period, delaying the decline rate of LAI, increasing the dry matter production capacity of cotton population, improving cotton production capacity of dry matter, promoting assimilates transfer to reproductive organs, and reducing the shedding of squares and bolls, which provided the material basis for the formation of cotton yield.

Key words: cotton, reduced application of nitrogen, operation of phosphorus and potassium, yield, leaf area index (LAI), drip-irrigation, Northern Xinjiang