基于功能细根直径分级的北疆棉花节水增产灌溉阈值研究OA

Drip irrigation under plastic mulch is widely practiced in cotton fields of northern Xinjiang,following the empirical mode of"frequent and light irrigation".However,the lack of quantitative criteria for irrigation frequency and volume has led to shallow root systems,low water use efficiency(WUE),and large interannual yield fluctuations.To address this issue,seven irrigation treatments were established in a typical oasis cotton field in Changji City,and the response thresholds of five fine-root diameter classes(0～4.5 mm)to soil moisture lower limits were systematically quantified using WinRHIZO Pro.The results showed that:① During the bud stage,the 70%field capacity(FC)treatment(F2B)significantly increased the length,surface area,and volume of 0～2.5 mm fine roots by 53.81%,54.80%,and 60.63%,respectively,compared with conventional farmers'practice(CK),while the total irrigation amount decreased by 34.27%.② The seed cotton yield of F2B3(70%FC at both bud and flowering and boll stages)reached 7 154.7 kg/hm2,a significant increase of 32.45%over CK,while WUE increased from 1.56 kg/m3 to 2.78 kg/m3(a 78%improvement).The upper half mean length and breaking strength of fibers increased by 6.92%and 4.93%,respectively.③ Soil moisture content in the 20 cm layer was significantly positively correlated with yield(R=0.85,p<0.05)and boll number per plant(R=0.73,p<0.05),indicating the critical role of surface soil moisture in boll formation,while root indices indirectly influenced yield.A threshold-based irrigation strategy(70%FC at bud and flowering and boll stages+21 high-frequency irrigations)was proposed,providing replicable technical parameters for precision drip irrigation of cotton in arid regions.