Effect of deep fertilizer application on flag leaf's photosynthetic characteristics and yield formation of spring wheat under drought conditions
[Objective]The objective of this study was to explore the impact of fertilizer application depth on the photosynthetic characteristics and yield formation of flag leaves in spring wheat,aiming to offer a theoretical basis for the deep fertilization of dryland spring wheat.[Method]A pot experiment was con-ducted using Longchun 35 spring wheat,implementing four treatments:wet chemical fertilizer applied shal-lowly at 15 cm(W15),wet chemical fertilizer applied deeply at 30 cm(W30),dry chemical fertilizer applied shallowly at 15 cm(D15),and dry chemical fertilizer applied deeply at 30 cm(D30).The SPAD value,leaf area,photosynthetic parameters,dry matter accumulation,filling rate,and yield of spring wheat flag leaves were assessed.[Result]Deep fertilizer application(W30,D30)notably enhanced the leaf area,dry matter ac-cumulation,filling rate,and SPAD value of flag leaves in dryland spring wheat.It facilitated the transfer of assimilated dry matter to seeds.At the flag picking stage,the SPAD values of flag leaves increased by 3.1%and 5.8%in the deep fertilizer treatments(W30 and D30)compared to the shallow fertilizer treat-ments(W15 and D15).The leaf area of flag leaves increased by 19.5%and 23.7%,respectively.Moreover,the average filling rate from 20 days to 40 days after flowering increased by 7.0%and 6.7%,respectively,and the dry matter accumulation per plant at maturity increased by 12.9%and 11.1%,respectively.Photo-synthetic parameters Pn,Gs,and Tr were significantly higher with 30 cm fertilizer depth compared to 15 cm depth,while Ci showed the opposite trend,particularly pronounced under drought conditions.Thousand grain weight and grain number increased by 14.0%,7.7%,and 3.8%,9.3%,respectively,with deeper fer-tilization(W30,D30)compared to shallower fertilization(W15,D15),resulting in a yield increase of 13.0%and 16.0%.[Conclusion]Deep fertilization can mitigate water deficits,enhance photosynthesis and grain filling in spring wheat,and sustain high economic and biological yields.This approach may be recommended for adoption in dry spring wheat cultivation in the northwest Loess Plateau.
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