旱地冬小麦关键期补灌追肥对产量及水氮利用效率的影响OA

[Background]Seasonal drought is a key limiting factor for rainfed winter wheat in the Loess Plateau in Northwestern China.To address this challenge,this paper experimentally explores the regulatory effect of limited supplemental irrigation and nitrogen topdressing at key growth stages on yield and water and nitrogen use efficiency of winter wheat.[Method]The field experiment was conducted using a rainwater-harvesting drip irrigation system.There were three irrigation treatments:irrigating 15 mm of water at the jointing stage(W1);irrigating 15 mm of water at the overwintering stage and the jointing stage respectively(W2);irrigating 15 mm of water at the overwintering stage,jointing stage and flowering stage respectively(W3).Each irrigation treatment had three nitrogen treatments by applying 120(N1),180(N2)and 240 kg/hm2(N3),respectively.The control was rainfed with 240 kg/hm2 of nitrogen application(CK).During the experiment,we measured dry matter accumulation,grain yield,and water and nitrogen use indictors.The optimal irrigation and nitrogen topdressing regime was identified using the TOPSIS method.[Result]Yield showed a marginally diminishing response to increased irrigation(W3 ≈ W2＞W1＞CK)and a unimodal response to nitrogen input,with N2 being optimal.Appropriate water-nitrogen combinations significantly enhanced pre-anthesis dry matter translocation.However,under drought stress conditions,excessive nitrogen application(N3)inhibited assimilate translocation and reduced both water use efficiency(WUE)and nitrogen partial factor productivity.The highest yield(4 188 kg/hm2)was achieved under W3N2.Yields in W2N2 and W3N2 were not significantly different,and WUE in W2N2 was 2.85 kg/m3,the highest among all treatments.TOPSIS analysis ranked W3N2 as the optimal treatment,followed by W2N2.[Conclusion]When harvested rainwater is sufficient,the W3N2 combination is the best,while when it is limited,W2N2 is optimal to best balance yield and water use efficiency.