固定灌水定额下过大灌水间隔抑制棉花生长及产量形成OA

[Objective]To clarify the impact of irrigation intervals on cotton yield and water use efficiency(WUE)under fixed ir-rigation quotas,this study analyzed the dynamic responses of cotton growth to uncover the physiological mechanisms regulating yield and WUE.These findings provide a theoretical basis for high-yield and high-efficiency drip-irrigated cotton production.[Methods]A two-year(2023-2024)field experiment was conducted at the Water Conservancy Irrigation Experimental Station in Bozhou,Xinjiang.Four irrigation interval gradients were designed:10 d(CK,control),15 d(W1),20 d(W2),and 25 d(W3).The responses of cotton leaf area,root-to-shoot ratio,dry matter accumulation,yield,and WUE to different irrigation intervals were quantitatively analyzed,and the key factors causing variations in yield and WUE were identified.[Results]In the 2-year experiment,the Leaf Area Duration(LAD)of cotton at each growth stage consistently followed the trend of CK>W1>W2>W3.Additionally,a logistic growth curve was established to reflect the growth status of cotton leaves.The results indi-cated that when the irrigation interval exceeded 15 days,the maximum growth rate of cotton leaves decreased by 4.06%～45.49%,while the effective leaf area growth period was extended by 8 to 13 days.When the irrigation interval exceeded 15 days,both the maximum aboveground dry matter accumulation rate and the maximum aboveground dry matter accumulation showed significant declines,with reductions of 18.13%～50.96%and 17.07%～83.73%,respectively.The root-to-shoot ra-tio of each treatment increased with the increase of irrigation intervals,with the W3 treatment showing a 4.73%～65.08%in-crease compared to the other treatments.Cotton yield and its components also exhibited trends consistent with the changes in dry matter accumulation.When the irrigation interval exceeded 15 days,the yield reduction ranged from 19.73%～93.26%.WUE exhibited an"initial increase followed by decrease"trend,whereas irrigation water use efficiency(IWUE)showed a"in-crease-decrease-increase"pattern.Structural equation modeling(SEM)demonstrated that irrigation intervals not only directly affected yield and WUE,but also indirectly influence them through their direct effects on leaf area and aboveground dry matter.[Conclusion]When the irrigation intervals was greater than 15 days,cotton leaf area and dry matter accumulation were signifi-cantly negatively affected,ultimately leading to a reduction in yield and water use efficiency.