Wheat grain zinc nutrition as affected by cultivar and nutrient management
[Objectives]Wheat grain Zn content plays important roles for ensuring human Zn nutrition.We studied the influence factors causing the low grain Zn content,to provide reference for maximizing wheat Zn nutrition through breeding and nutrient management.The function of arbuscular mycorrhizal fungi(AMF)is one of the important ways to improve agricultural sustainability.[Methods]Pot culture method was used in this study.The four winter wheat cultivars were bred in different decades:Mazha in 1940s(MZ),Bima 1 in 1950s(BM),Fengchan 3 in 1960s(FC),and Changhan 58 in 2010s(CH).For each cultivar,two phosphorus treatments were set up as no P application and applying P 200 mg/kg;and two inoculation treatments as:without inoculation(CK)and inoculation of 60 g Rhizophagus intraradices(A).At pre-and post-anthesis stages,the wheat plant biomass,yield,and root mycorrhizal infection rate were investigated,the Zn contents in plant and grains were analyzed,the responsiveness of mycorrhizal growth(MGR),shoot zinc uptake(MZnR)and P uptake(MPR)of each cultivar were then calculated,and the importance of zinc absorption related traits was determined for the grain Zn content using the partial least squares path analysis(PLS-PM).[Results]The grain yield differed significantly among cultivars under different treatments and the grain yield increased significantly with the replacement of cultivars,while the grain zinc concentration decreased with the replacement of cultivars.Compared with LP-CK treatment,the HP-CK treatment increased the grain yield by 36.73%-42.16%,significantly reduced the grain Zn concentration by 11.57%-27.07%,and the Zn accumulation of FC and CH increased by 25.75%and 14.44%,respectively.The mycorrhizal colonization rates differed significantly among cultivars under LP-A treatment,but the differences lost and the colonization rates declined under HP-A.Compared with LP-CK treatment,the LP-A treatment increased grain Zn concentration by 6.78%-9.37%,and the Zn accumulation increased by 23.75%-29.79%.While only the grain zinc accumulation of CH in HP-A treatment was significantly higher than that in HP-CK treatment.P application significantly reduced MPR of all the cultivars by 99.29%-140.76%,reduced the MZnR,MGR of BM,FC and CH by 56.47%-67.18%,68.22%-71.77%,respectively.The results PLS-PM showed that the cultivar had the greatest effect on the grain zinc concentration(-0.656),followed by phosphate fertilizer(-0.557),yield(-0.456)and AMF(0.191).The modern cultivar CH always showed lower grain zinc concentration and higher grain zinc accumulation.[Conclusions]The yield potential of cultivar and nutrient management are the most important factors deciding the wheat grain Zn content.High yield produces dilution effect,and the fertilization will exaggerate the dilution effect.AMF inoculation shows a certain effect on the Zn uptake,but the effect will be offset greatly by fertilization.Therefore,Zn fertilization should be paid attention in modern wheat cultivars.
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