| To determine the effect of nitrogen(N)fertilizer rates and Arbuscular Mycorrhizal Fungi(AMF)on maize growth,two pot experiments were established to study the effects of inoculation with AMF on maize nutrient absorption during the vegetative growth period and yield,nutrient absorption and grain quality during the grain filling period under different N fertilizer conditions.Experiment one was the summer maize vegetative growth period,the two factors were nitrogen fertilizer treatments: 180 kg N hm-2(N1),270 kg N hm-2(N2),and mycorrhizae treatments: No AMF inoculation(M-),AMF inoculation(M+).Divided into five samplings,respectively at the four-leaf stage(V4),six-leaf stage(V6),and eight-leaf stage(V8),ten-leaf stage(V10),twelve-leaf stage(V12)sampling.The maize root colonization,biomass of differences organs,N,phosphorus(P),potassium(K)content and their accumulation,root activity and root characteristics maize were measured.The second experiment was the summer maize vegetative growth period,the experiments was set on Zhengzhou and Shangqiu at the same time and the experiment treatments was the same as the experiment one,.Divided into five samplings,respectively at the 10 days(10d),20 days(20d),30 days(30d),40 days(40d)and 50days(50d)after spinning.The maize root colonization,biomass of differences organs,N,P,K content and their accumulation,grain enzyme activity and their gene expression,grain quality and root characteristics maize were measured.The optimal ratio of N fertilizer rates and AMF was obtained from the two experimental results,which provided a theoretical basis for increasing yield,nutrient absorption and improving grain quality.The main research results were as follows: In the experiment of vegetative growth period,the interaction between nitrogen fertilizer and AMF can significantly increase the biomass of maize,especially under high nitrogen conditions.The N accumulation in each part gradually increases with the growth period,compare wuth M-,the presence of M+ increased root,stem and leaf N accumulation increased by7.1%,1.0% and 17.6% with N1 condition,and increased 30.0%,11.6% and 10.1%;the P accumulation in each part gradually increased with the growth period,compare with M-,the presence of M+ increased root,stem and leaf P accumulation increased by 7.8%,28.1% and 7.3% with N1 condition,and increased 60.4%,36.9% and 10.0%;the K accumulation in each part gradually increased with the growth period,compare with M-,the presence of M+ increased stem and leaf K accumulation increased by5.1% and 12.1% with N1 condition,and root,stem and leaf K accumulation increased60.4%,36.9% and 10.0%.In the grain filling period experiment,the biomass and grain weight of maize increased gradually with the grain filling period of maize.AMF could increase the corn biomass and grain weight under different nitrogen fertilizer conditions of the two experimental sites.The effect of AMF on the corn biomass and grain weight was more significant under low nitrogen conditions,compare with M-,the presence of M+increased grain weight increased by 14.4% in two experimental sites.The grain N accumulation increased gradually,and the root,stems,leave and other parts N accumulation increased first and then decreased.Compare with M-,the presence of M+ increased grain,root,stem and leaf and other parts N accumulation increased by14.5%,9.6%,8.2%,5.7% and 15.6% with N1 condition in two experimental sites,and increased by 13.1%,9.5%,15.0%,7.7%,14.7% in two experimental sites;the grain P accumulation increased gradually,and the root,stem,leave and other parts P accumulation increased first and then decreased;compare with M-,the presence of M+ increased grain,root,stem and leaf and other parts P accumulation increased by24.7%,21.1%,11.0%,7.3% and 17.4% with N1 condition in two experimental sites,and increased by 19.5%,10.5%,7.1%,11.0%,10.4% in two experimental sites;the grain and root K accumulation increased first and then decreased with the grain filling period,the stem K accumulation increased gradually,and the leaf and other parts K accumulation gradually decreased,compare with M-,the presence of M+ increased grain,root,stem and leaf and other parts K accumulation increased by 35.7%,11.7%,12.3%,20.5% and 9.5% with N1 condition in two experimental sites,and increased by 25.2%,15.3%,9.7%,14.0% and 25.5% in two experimental sites.During the grain filling period,the nitrate reductase(NR),nitrite reductase(NIR),glutamine synthetase(GS)and glutamine synthase(GOGAT)activities were significantly increased in two experimental sites with AMF inoculated under different N fertilizer conditions;and the gene expression of enzyme was also significantly increased.In the grain filling period,the crude protein and lysine decreased gradually,the crude starch increased gradually,and the crude fat increased and then decreased.Compared with M-,the presence of crude protein,crude fat and lysine increased by11.3%,5.2% and 11.3% with N1 condition in two experimental sites,and 11.3%,5.1% and 10.3% with N2 condition in two experimental sites.The results of correlation analysis showed that biomass,N,P and K accumulation(except stem P accumulation)of maize with enzyme activities related to grain nitrogen metabolism and root traits had significantly positive correlation.The crude protein with enzyme activities related to grain nitrogen metabolism,root traits,AMF colonization,leaf area index(LAI)and SPAD values had significant positive correlation.These results showed: that AMF inoculation under different nitrogen fertilizer conditions could significantly increase the biomass,grain weight and accumulation of N,P and K in maize at different period,improve the enzymes activities related to nitrogen metabolism in maize at grain filling stage and significantly up-regulated the gene expression of enzymes related to nitrogen metabolism,and improve maize grain quality.The effect of AMF on maize growth was better in the condition of high N in the vegetative growth period,and better in the condition of low N in the grain filling period.In order to improve nutrient absorption,grain quality and grain weight of maize,it is considered that AMF inoculated with 180kg·N hm-2 was the best combination of fertilizer application for increasing yield,increasing nutrient absorption and improving grain quality on maize in our test. |
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