氮肥减量配施腐殖酸肥对水稻根系形态生理、产量及品质的影响OA

[Objective]Identifying the pathways by which humic acid fertilizer combined with nitrogen re-duction synergistically improves the yield and grain quality of rice varieties with different nitrogen-use ef-ficiencies,this study explores the integrated application technique of reduced nitrogen fertilizer with hu-mic acid fertilizer.The findings aim to provide a theoretical basis and technical support for achieving high-yield,high-efficiency,and high-quality rice cultivation.[Method]A two-factor randomized block design was adopted,using N high efficient variety Dexiang 4103 and N low efficient variety Yixiang 3724 as test materials.Six treatments were established:no N application(N0),only 75 kg/hm2 humic acid fertilizer(N1),N1 plus 120 kg/hm2 N application(N2),N1 plus 150 kg/hm2 N application(N3),N1 plus 180 kg/hm2 N application(N4),and only 210 kg/hm2 N application(N5).The effects of reduced N fertil-izer combined with humic acid fertilizer on root morphological physiology,yield,and quality of rice with different N efficiencies were studied,and the relationship between root morphological physiology and yield and quality was explored.[Result]Different N-efficient rice cultivars and the treatment of re-duced N fertilizer combined with humic acid had significant effects on root morphological and physiologi-cal characteristics,dry matter accumulation and translocation,yield,and quality.Compared with the N low-efficient variety,the N high-efficient variety exhibited significant increases in root morphology at key growth stages,root nitrate reductase(NR)and glutamine synthetase(GS)activities,dry matter ac-cumulation during the grain-filling stage,and population growth rate by 9.91%-35.57%,9.13%-64.07%,20.63%-44.43%,and 22.49%-31.98%,respectively.These improvements contributed to a significant yield increase of 9.60%-14.77%,which is the key pathway for the high yield of the N high-efficient vari-ety.However,the chalky grain rate of the N high-efficient variety increased by 8.70%-9.87%,and the taste value decreased by 10.56%-11.03%.For all tested varieties,the N3 treatment significantly improved root morphology(root length,root diameter,and root volume)at the jointing and heading stages by 5.59%-15.35%,enhanced key root N metabolism enzyme activities(NR and GS)by 28.37%-48.57%,pro-moted dry matter accumulation during the grain-filling stage by 0.14%-10.68%,and increased the popu-lation growth rate by 0.16%-10.82%.Consequently,yield was significantly increased by 4.73%-15.03%.Moreover,without significantly reducing the taste value,the appearance quality of rice was further improved,making the N3 treatment the optimal mode of reduced N fertilizer combined with humic acid fertilizer in this experiment.Correlation analysis revealed significant relationships between yield traits and rice quality characteristics and root volume at the jointing stage,NR enzyme activity at the jointing and maturity stages,GS enzyme activity at the heading and maturity stages,as well as dry matter accumulation and population growth rate during the grain-filling stage.[Conclusion]Under different re-duced N fertilizer treatments combined with humic acid fertilizer,both varieties achieved the goals of re-ducing N application,increasing yield,and improving quality through a cascading effect:optimization of root morphology → enhancement of root enzyme activity → acceleration of dry matter translocation in stems and leaves during the grain-filling stage → increased yield and reduced chalkiness.However,dif-ferentiated fertilization strategies should be formulated for varieties with different N efficiencies to bal-ance the synergistic improvement of yield and taste quality.