| Clarifying the effect of arbuscular mycorrhizae fungi(AMF)on maize physiological characteristics during grain filling periods,and grain yield and their quality,could provide a theoretical basis for the reasonable using of biological fertilizer in farmland,increasing maize yield and improving grain quality.This study was carried two-factors pot experimentwas using chambers(growth chamber and hyphal chamber).The factors were nitrogen fertilizer forms(NH4+-N: ammonium nitrogen fertilizer;NO3--N: nitrate nitrogen fertilizer)and arbuscular mycorrhizal fungi(M0: neither root nor arbuscular mycorrhizal fungi could pass through the compartment;M1: only arbuscular mycorrhizal fungi could pass through the compartment).In the two experimental years of 2018 and 2019,we measured organs’ biomass,organs’ nitrogen accumulation,leaf area,SPAD value,key enzymes for nitrogen metabolism in panicle leaves and grains(Nitrate reductase,NR;Nitrite reductase,Ni R;Glutamine synthase,GS;and glutamate synthase,GOGAT),root colonization indensity,spore number in soil,root characteristics and so on during grain filling and mature periods,respectively.In the end,we analyzed these results by correlation analysis.The main results of this experiment were as follows: without arbuscular mycorrhizal fungi,compared with the mean value of ammonium nitrogen fertilizer treatment,the yield and nitrogen accumulation of maize under the nitrate nitrogen fertilizer treatment increased by 14.13% and 14.12%,respectively.With arbuscular mycorrhizal fungi,compared with the mean value of the M0 treatment,the yield and grain nitrogen accumulation under the ammonium nitrogen fertilizer treatment increased by 85.32% and 140.13%,respectively;the yield and grain nitrogen accumulation under the nitrate nitrogen fertilizer treatment increased by 36.12% and81.17%,respectively.Effects of nitrogen fertilizer forms and arbuscular mycorrhizal fungi on the physiological characteristics of maize during grain filling periods:without arbuscular mycorrhizal fungi,compared with the mean value of ammonium nitrogen fertilizer treatment,the mean SPAD of maize under the nitrate nitrogen fertilizer treatment decreased by 4.34%,while the mean leaf area of maize increased by 4.56% compared with the mean value of ammonium nitrogen fertilizer,and the net photosynthetic rate,stomatal conductance,intercellular carbon dioxide concentration and transpiration rate of maize under the condition of nitrate nitrogen fertilizer increased by 11.51%,38.89%,254.09% and 43.32%,respectively.With arbuscular mycorrhizal fungi,compared with the mean value of M0 treatment,the SPAD and leaf area of M1 increased by 20.23% and 18.16%,respectively,and the SPAD and leaf area under the nitrate nitrogen fertilizer treatment increased by 24.13% and 13.26%,respectively;compared with the mean value of M0,the net photosynthetic rate,stomatal conductivity and intercellular carbon dioxide concentration under the ammonium nitrogen fertilizer increased by 18.72%,16.27% and 154.5%,respectively,and the net photosynthetic rate,stomatal conductivity and stomatal conductivity of maize under the nitrate nitrogen fertilizer.The intercellular carbon dioxide concentration and transpiration rate increased by 25.35%,42.8%,125.94% and 17.3%,respectively.The activities of NR,Ni R,GS and GOGAT enzymes in maize panicle leaves showed a tendency to increase first and then decrease.Under the condition of no bacterium,compared with the mean value of ammonium nitrogen fertilizer treatment,the NR enzyme activity of maize leaves under the nitrate nitrogen fertilizer treatment increased by 11.23%.After the bacterium treatment,the NR,Ni R,GS and GOGAT enzyme activities of M1 maize panicle leaves increased by 16.32%,20.13%,14.23%and 26.24%,respectively,compared with the means of M0 treatment,and the NR,Ni R,GS and GOGAT enzyme activities of M1 maize panicle leaves increased by21.11%,49.25%,31.13% and 8.34%,respectively.The activities of NR,Ni R,GS and GOGAT enzymes in grains showed an increase trend under ammonium nitrogen fertilizer conditions,and under the conditions of nitrate nitrogen fertilizer,NR and Ni R enzyme activities showed a gradual increase trend,and GS and GOGAT enzyme activities decreased first and then increased.Compared with the means of ammonium nitrogen fertilizer treatment,the NR,Ni R,GS and GOGAT enzyme activities of grains under the nitrate nitrogen fertilizer treatment increased by 13.11%,24.31%,11.02% and 22.04%,respectively.Compared with the means of M0 treatment,the NR and Ni R enzyme activities of maize grain M1 decreased by 4.01% and 12.08%,respectively,while the activities of GS and GOGAT enzymes increased by 4.88% and4.76%,respectively,compared with the mean values of M0 treatment,and the NR and GOGAT enzyme activities of grains under the nitrate nitrogen fertilizer treatment decreased by 6.32% and 6.11%,respectively,while the activities of GS enzyme increased by 4.78%.Effects of nitrogen fertilizer forms and arbuscular mycorrhizal fungi on maize grain quality: The effect of nitrogen fertilizer form on grain quality was not significant without arbuscular mycorrhizal fungi.With arbuscular mycorrhizal fungi,compared with the M0,crude protein content,crude starch content and Lysine content of M1 under the NH4+-N treatment increased by 9%,6% and 7%,respectively;and crude fat content reduced by 19%,However,crude protein content and Lysine content of M1 under the NO3–-N treatment increased by 10% and 8%,and crude fat content reduced by 32%,respectively.These results show that ammonium nitrogen fertilizer is more conducive to the improvement of maize grain yield than nitrate nitrogen fertilizer without arbuscular mycorrhizal fungi,and the influence of nitrogen fertilizer form on grain quality is not significant.With arbuscular mycorrhizal fungi,arbuscular mycorrhizal fungi can significantly increase the yield and improving grain quality of maize under the conditions of ammonium nitrogen fertilizer and nitrate nitrogen fertilizer,and the effect is better under the condition of ammonium nitrogen fertilizer. |
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