Effects Of Different Irrigation Quotas Combined With Liquid Fertilizers On Cotton Growth And Water And Nitrogen Utilization Efficiency

In response to the low water and fertilizer utilization efficiency of cotton in southern Xinjiang,a field experiment with irrigation quotas and different ratios of liquid fertilizer was conducted at the Korla Baotou Lake Base of the Xinjiang Academy of Agricultural Sciences in 2022.Four different irrigation quotas W₁（3600m³/hm²）,W₂（4200m³/hm²）,W₃（4800m³/hm²）,W₄（5400m³/hm²）,and two liquid fertilizers Y₁and Y₂were set up in the experiment to study the effects of different water and fertilizer interactions on cotton growth,nutrient accumulation and distribution,yield and composition factors,and water and fertilizer utilization efficiency,providing theoretical basis and technical support for cotton water and fertilizer management in southern Xinjiang.The main research findings are as follows:（1）Under different water and fertilizer treatments,there are varying degrees of differences in various agronomic indicators of cotton plants.Under the same irrigation treatment,Y₁and Y₂treatments had a significant impact on agronomic indicators such as cotton plant height,stem diameter,number of fruit branches,and height of fruit branch beginning nodes;Under the same fertilization treatment,there is a significant difference in agronomic indicators such as cotton plant height among different irrigation treatments,showing a trend of first increasing and then decreasing with the increase of irrigation water,achieving the highest level at W₃irrigation level;Under various water and fertilizer treatments,W₃Y₂treatment had the highest agronomic indicators,while W₁Y₁treatment had the lowest.After topping,there was no significant change in cotton plant agronomic indicators.（2）Under different water and fertilizer treatments,there are significant differences in the accumulation and distribution of dry matter in cotton at different growth stages.Under the same irrigation treatment,the dry matter accumulation of cotton vegetative organs in Y₁and Y₂treatments significantly increased compared to Y₀from bud stage to boll stage;The dry matter distribution coefficient of cotton vegetative organs significantly decreased compared to reproductive organs.Under the same fertilization treatment,there was a significant difference in dry matter accumulation and boll distribution coefficient in the reproductive organs of cotton plants from flowering and boll opening stage to boll opening stage,but different irrigation treatments showed a trend of first increasing and then decreasing with the increase of irrigation water amount;The dry matter accumulation and boll distribution coefficient of cotton under different irrigation treatments are shown as follows:W₃>W₂>W₄>W₁.Under each water and fertilizer treatment,the cotton under W₃Y₂fertilization treatment has the highest dry matter accumulation and distribution.This indicates that the amount of irrigation plays a leading role in the accumulation of dry matter in cotton during the boll opening period,but has no significant impact on the distribution of dry matter in various organs of cotton.（3）Under different water and fertilizer treatments,there were significant differences in nitrogen accumulation and distribution in cotton from flowering and boll stage to boll opening stage.Under the same irrigation level,there was little difference in nitrogen accumulation and distribution among cotton plants treated with Y₁and Y₂,but both treatments were higher than Y₀;Under the same fertilization treatment,there were significant differences in nitrogen accumulation and distribution in cotton under different irrigation treatments from flowering and boll stage to boll opening stage.As the irrigation amount increased,it showed a trend of first increasing and then decreasing.The nitrogen accumulation in cotton under each irrigation treatment was as follows:W₃>W₂>W₄>W₁,seed+fiber>boll shell>leaf>stem;Under various water and fertilizer treatments,W₃Y₂fertilization treatment had the highest nitrogen accumulation and distribution in cotton,while W₁Y₁treatment had the lowest.（4）The interaction of different water and fertilizer has a significant impact on cotton yield and composition factors.Compared with the control,the cotton yield of liquid fertilizers Y₁and Y₂increased by 4.28%and 12.36%.Under the same fertilization treatment,the cotton yield and composition factors of different irrigation treatments showed a trend of first high and then low with the increase of irrigation water,and the difference reached a significant level.The cotton yield ranking of each irrigation treatment was:W₃>W₂>W₄>W₁;Under various water and fertilizer treatments,the yield of W₃Y₂interaction was the highest at 7 963.40kg/hm²,while W₁Y₁had the lowest at 6 706.80kg/hm²,but had no significant effect on cotton lint percentage.（5）Under different water and fertilizer treatments,there are significant differences in cotton’s water use efficiency,nitrogen fertilizer apparent utilization efficiency,fertilizer partial production rate,and agronomic utilization efficiency.Under the same irrigation treatment,there were significant differences in cotton water use efficiency,nitrogen fertilizer apparent utilization efficiency,nitrogen fertilizer agronomic efficiency,nitrogen absorption efficiency,and nitrogen fertilizer partial productivity between Y₁and Y₂treatments;Under the same fertilization treatment,there were significant differences in cotton water use efficiency,nitrogen fertilizer agronomic efficiency,nitrogen absorption efficiency,nitrogen fertilizer apparent utilization efficiency,and nitrogen fertilizer partial productivity among different irrigation treatments.With the increase of irrigation amount,there was a trend of first increasing and then decreasing,reaching the highest under W₃irrigation.Under various water and fertilizer treatments,the cotton treated with W₃Y₂had the highest water and fertilizer utilization efficiency,while the W₁Y₁treatment had the lowest.The water use efficiency was 14.31%higher than the control,and the nitrogen fertilizer absorption efficiency was 18.70%higher than the control;The water and fertilizer utilization efficiency of cotton treated with liquid fertilizer is significantly better than that of the control.The optimal irrigation quota for liquid fertilizer Y₂is 4800m³/hm²,which can achieve efficient utilization of cotton water and fertilizer.