| To determine the effect of different nitrogen fertilizer forms and Arbuscular Mycorrhizal Fungi(AMF)on maize growth,providing a theoretical basis for improving summer maize nutrient absorption and reducing soil nitrous oxide(N2O)emissions.A two-factor experiment was established.The two factors were different nitrogen fertilizer forms(NH4+-N:ammonium nitrogen fertilizer,NO3--N:nitrate nitrogen fertilizer),and mycorrhizae treatments(the root and arbuscular mycorrhizal fungi can not pass through the compartment:M0,only arbuscular mycorrhizal fungi can pass through the compartment:M1,both root and arbuscular mycorrhizal fungi can pass through compartment:M2).The maize yield,biomass,root traits,nitrogen accumulation,soil NH4+-N,NO3--N content,N2O emission were measured.The main research results are as follows:different nitrogen fertilizer forms have different effects on the growth and yield of maize.Compared with ammonium nitrogen fertilizer treatment,the average grain yield of nitrate nitrogen fertilizer treatment decreased by 11.71%.The total root length,root surface area,the root volume decreased by 10.64%,8.52%and 6.47%,respectively,while the root diameter increased by 1.72%.The root infection rate decreased by 10.83%,the number of soil spore increased by 15.73%,respectively.The two-year average nitrogen accumulation in the shoot and root of maize decreased by 13.84%and 7.77%,respectively.The two-year average content of nitrate nitrogen increased by 6.39%,the average content of ammonium nitrogen content decreased by 32.63%.The average of isotopic nitrogen content in grain of maize decreased by 22.71%,and the average of isotopic nitrogen content in the aboveground and root of maize decreased by 34.55%and 26.64%,respectively,while the average isotopic nitrogen content of soil increased by 6.99%.Among the three arbuscular mycorrhizal fungi treatments,compared to M0 treatment,M1 and M2 increased grain yield by 55.66%,152.62%,63.47%and 165.59%under ammonium nitrogen fertilizer and nitrate nitrogen fertilizer for two consecutive years,respectively.The aboveground biomass of maize increased by 11.52%,16.83%,6.76%and 16.51%,respectively.The root biomass of maize increased by 30.21%,48.53%,13.44%and 36.93%,respectively.The root length increased respectively 98.79%,153.91%,57.47%and 86.42%,the root surface area increased by 79.29%,144.21%,54.22%and 83.23%,the root diameter decreased by 8.86%,3.52%,3.83%and 3.32%,the root volume increased by 60.54%,135.97%,51.97%and 82.85%,respectively.The root infection rates increased by 130.88%,154.45%,200.34%and 242.07%,respectively.The soil spore number increased by 125.24%,277.08%,98.33%and 251.67%,respectively.The aboveground nitrogen accumulation increased by 119.27%,206.74%,198.78%and 283.02%,root nitrogen accumulation increased by 57.08%,106.26%,128.75%and 156.59%,respectively.The content of nitrate nitrogen decreased by 15.04%,86.71%,6.68%and 85.44%,the content of ammonium nitrogen decreased by 52.49%,88.85%,92.36%and 90.22%,respectively.The isotopic nitrogen content of aboveground increased by 1273.54%,1796.64%,751.91%and 1214.23%,the isotopic nitrogen content of root increased by 959.02%,1055.65%,623.13%and 653.17%,the isotopic nitrogen content of soil decreased by 64.31%,88.46%,13.34%and 43.21%,respectively.The N2O emission flux changed dynamically during the whole growth period of maize,and different nitrogen fertilizer forms had different effects on the N2O emission flux.Compared with ammonium nitrogen fertilizer treatment,the average N2O emission flux for nitrate nitrogen fertilizer treatment increased by 49.75%,respectively.The abundance of nirK,nirS and nosZ in maize soil increased by 39.21%,38.92%and 33.84%,respectively.Compared to M0 treatment,M1 and M2 decreased N2O emission flux by 76.89%,76.42%,45.57%and 80.31%under ammonium nitrogen fertilizer and nitrate nitrogen fertilizer for two consecutive years,respectively.The abundance of nirK in maize soil decreased by 58.73%,49.69%,51.46%and 54.23%,the abundance of nirS in maize soil decreased by 35.54%,48.99%,9.73%and 9.17%,the abundance of nosZ in maize soil increased by 59.54%,78.86%,63.18%and 191.39%,respectively.The results of multivariate ANOVA showed that nitrogen fertilizer forms and arbuscular mycorrhizal fungi had different effects on maize yield,biomass,nitrogen accumulation,nitrate nitrogen content,ammonium nitrogen content and N2O emission.Nitrogen fertilizer forms had no significant effects on biomass and nitrate nitrogen content.Arbuscular mycorrhizal fungi had significant effects on all of them.The interaction of nitrogen fertilizer forms and arbuscular mycorrhizal fungi had significant effects on ammonium nitrogen content and N2O emission.The results of correlation analysis showed that grain yield and biomass,root nitrogen accumulation,shoot nitrogen accumulation had significant positive correlation.The grain yield and ammonium nitrogen content,nitrate nitrogen content and N2O emission had negative correlation.The abundances of nirK and nirS in maize soil were positively correlated with N2O emission flux and cumulative emission,while the abundance of nosZ was negatively correlated with N2O emission flux and cumulative emission.The root volume,root surface area,root length,soil spore number and root infection rate were positively correlated with grain yield,biomass and nitrogen accumulation.The root diameter,soil ammonium nitrogen and nitrate nitrogen contents were negatively correlated with corn grain yield,biomass and nitrogen accumulation.These results show that ammonium nitrogen fertilizer is more conducive to improving grain yield and nitrogen accumulation,and significantly decreases the ratio of(nirK+nirS)/nosZ,thereby decreasing the N2O emission of maize soil.Arbuscular mycorrhizal fungi significantly increases the uptake,utilization of soil nitrogen and grain yield,by decreasing the abundance of nirK,nirS and increasing the abundance of nosZ.Arbuscular mycorrhizal fungi significantly decreases the ratio of(nirK+nirS)/nosZ and N2O emission flux.In actual production,according to soil characteristics and cultivation measures,ammonium nitrogen and nitrate nitrogen fertilizers should be properly added and inoculated with arbuscular mycorrhizal fungi,which can improve soil nitrogen utilization efficiency and reduce nitrogen loss.In order to provide theoretical support for alleviating the greenhouse effect and achieving green ecological sustainable development of agriculture. |
PDF Full Text Request