长期水氮定位对小麦幼苗质量及产量形成的调控效应OA

[Objective]To address the mismatch between the spatiotemporal distribution of water and fertilizer and the stage-specific demands of wheat,as well as the constraints on yield potential in the Huang-Huai-Hai region,this study investigates the characteristics of wheat yield formation under the condition of long-term water and nitrogen positioning,thereby providing a theoretical basis for high-yield and high-efficiency wheat cultivation.[Methods]Based on a long-term positioning experiment(initiated in 2015)at the Xinji Experimental Station of Hebei Agricultural University,a total of 9 water-nitrogen coupling treatments were established,including three water treatments and three nitrogen treatments.The water treatments were:no irrigation throughout the entire growth period(W0),one irrigation at the jointing stage(W1),and two irrigations at the jointing and flowering stages(W2).The nitrogen treatments were:no nitrogen application(N0),pure nitrogen of 120 kg/hm2(N1),and pure nitrogen of 240 kg/hm2(N2).The wheat variety"Gaoyou 2018"was used in the experiment,and the data were obtained from the monitoring results of the wheat growing seasons from 2023 to 2025.The study investigated the effects of long-term water and nitrogen treatments on the growth and physiological regulation as well as yield formation of winter wheat,focusing on changes in population stem number,dry matter accumulation and distribution,yield and its components,seedling growth indicators,and endogenous hormone contents.A partial least squares path model(PLS-PM)was employed to identify the main factors regulating yield formation.[Results]With the increase of irrigation and nitrogen application rates,wheat yield showed an upward trend.Among all treatments,the W2N2 treatment had the highest yield,but showed no significant difference from the W2N1 treatment.The W0 and N0 treatments failed to achieve high yields due to insufficient water and nitrogen supply.During the two growing seasons,compared with W1N1,W1N2 increased the yield by an average of 13.75％(p＜0.05).Compared with W2N1,W2N2 increased the yield by an average of 5.67％.In terms of irrigation effects,W2N1 increased the yield by an average of 18.10％compared with W1N1(p＜0.05),and W2N2 increased the yield by an average of 9.47％compared with W1N2.No significant differences were observed between the W2N2 and W2N1 treatments in spike number,1 000-grain weight,or total stem number at the flowering and maturity stages.However,compared with W2N1,W2N2 increased the grains per spike and dry matter accumulation at the maturity stage by an average of 11.98％(p＜0.05)and 5.46％(p＜0.05),respectively.In the second growing season,the spike formation rate of W2N1 was 15.40％higher than that of W2N2(p＜0.05),effectively compensating for the lower number of grains per spike.There was no significant difference in SPAD values between W2N1 and W2N2 treatments.However,nitrogen uptake efficiency and nitrogen fertilizer production efficiency under W2N1 treatment were significantly higher than those under W2N2 by 78％and 90％,respectively.At the seedling stage,plant height,number of secondary roots,and root dry weight under the N1 treatment were significantly higher than under the N2 treatment.Additionally,the contents of GA3 and IAA in the roots increased by 27.92％(p＜0.05)and 55.31％(p＜0.05),respectively,and the ABA content in the above-ground parts decreased by 18.99％(p＜0.05),establishing a solid foundation for vigorous seedlings.The partial least squares path model indicated that IAA and GA3 promoted nitrogen uptake by increasing root dry weight and root length,and significantly affected chlorophyll content,increasing nitrogen accumulation and nitrogen uptake efficiency.Total stem number showed a highly significant positive correlation with dry matter accumulation(path coefficient=0.996,p＜0.001).Dry matter accumulation showed a significant positive correlation with spike number(path coefficient=0.648,p＜0.01),ultimately affecting yield(path coefficient=0.777,p＜0.001).[Conclusion]Under the conditions of the long-term positioning experiment,the W2N1 treatment still achieves high wheat yield.This is mainly due to the high growth quality of wheat seedlings,which is characterized by high contents of growth-promoting hormones,good root development,and increased plant dry matter accumulation.Additionally,the improvements in the number of tillers,spike formation rate,SPAD,and nitrogen uptake efficiency at the middle and late growth stages ensure that the yield does not decrease significantly.This study provides data support for further reducing fertilizer application and enhancing efficiency in wheat production.