| Taking the different legumes and Pyrus sinkiangensis were used as monocropping and intercropping objects,Pyrus sinkiangensis monocropping,in 2020-2021.Medicago sativa 、Melilotus suaveolens and Vicia Villosa were developed in the 10 th region of Alar City,Xinjiang Uygur Autonomous Region.Respectively,intercropping Pyrus sinkiangensis with Medicago sativa,intercropping Pyrus sinkiangensis with Melilotus suaveolens,intercropping Pyrus sinkiangensis with sweet clover,and intercropping Pyrus sinkiangensis with Vicia Villosa.Different nitrogen fixation ability as the legumes intercropping system changing factors,from the perspective of biological nitrogen fixation,legumes were analyzed the different nitrogen fixation ability of leguminosae herbage and the influence of intercropping nitrogen transfer of Pyrus sinkiangensis,focus on resolving optimal nitrogen fixation ability of legumes and Pyrus sinkiangensis its ability of nitrogen fixation and nitrogen transfer under intercropping,nitrogen use efficiency of internal relations.Exhibit the following results:(1)Under the different intercropping patterns,the amount of nitrogen derived from air of the three legumes was in the range of 0.64-8.61 g·m-2,and the percentage of nitrogen derived from air was in the range of 26.6%-41.27%.The amount of nitrogen derived from air of Melilotus suaveolens reached the maximum value of 8.61 g·m-2 under monocropping,followed by Medicago sativa,which was 4.69 g·m-2,and 0.64 g·m-2 of Vicia Villosa.The percentage of nitrogen derived from air showed a trend as follows: Medicago sativa > Melilotus suaveolens > Vicia Villosa,which were 41.27%,39.58% and 39.03%,respectively.Under intercropping,the amount of nitrogen derived from air of legumes showed a trend of Medicago sativa > Melilotus suaveolens>Vicia Villosa.The amount of nitrogen derived from air of Medicago sativa was 5.17 g·m-2,and that of Vicia Villosa was 0.79 g·m-2.At the same time,the rhizobium amount and rhizobium enzymatic activity had significant effects on the nitrogen fixation ability of legumes(P<0.05).Under the Medicago sativa intercropping,the rhizobium characteristics were highest,which indicated that the intercropping had the greatest impact on the biological nitrogen fixation of Medicago sativa.The comprehensive comparison showed that the interspecific interaction of Medicago sativa would effectively stimulate the nitrogen fixation ability of root nodules of Medicago sativa,thus having a positive impact on the intercropped Pyrus sinkiangensis.(2)There was nitrogen transfer between Medicago sativa,Melilotus suaveolens,and Vicia Villosa intercropping with Pyrus sinkiangensis.The nitrogen transfer capacity of legumes was affected by AM colonization rate,AM colonization intensity and soil mycelium density.Under different intercropping patterns,the range of the amount of nitrogen derived from legume was 0.95 to 2.61 g·m-2,and the range of the percentage of nitrogen derived from legume was 0.54-1.25%.The maximum nitrogen transfer amount and nitrogen transfer rate of purple Medicago sativa were 3.48g·m-2 and 1.25%,respectively,which were 174.37% and 145.25% higher than that of Melilotus suaveolens and Vicia Villosa,respectively.The nitrogen transfer rate increased by 43.68% and228.94%,respectively.The infection frequency of AM fungus in Medicago sativa under intercropping was 27%,which was significantly higher than that in other treatments(P<0.05).At the same time,the infection intensity of AM fungi and the density of soil mycelium were also significantly affected(P<0.05).The density of rhizosphere soil mycelium had a significant effect on the nitrogen transfer capacity of legumes.This indicated that the AM fungus-legume herbage-rhizobium community was closely related to nitrogen transfer between legume and non-legume intercropping systems.(3)According to the root separation test,the frequency of AM fungi infection and the density of soil mycelium a in legume pasture under different separation methods were as follows:spaceless > mesh barrier > plastic barrier.Compared with Melilotus suaveolens and Vicia Villosa without interval,the frequency of AM fungal infection of Medicago sativa was significantly increased by 9.49% and 22.72%.The density of rhizosphere soil mycelium a was significantly higher than that of other treatments(P<0.05).Medicago sativa increased yield by 19.39% and 41.6%,respectively,compared with Melilotus suaveolens and Vicia Villosa without interval.The infection intensity of AM fungi in Medicago sativa separated by mesh barrier was the highest,and increased by 4.31% compared with that without mesh barrier.(4)The highest fruit biomass was reached under the intercropping of Pyrus sinkiangensis and Melilotus suaveolens(2522.33 g·plant-1),which increased by 7.05% compared with CK.Nitrogen application increased the yield by 8.2% compared with CK.The highest n content was 14.38 g·kg-1under the intercropping of Pyrus sinkiangensis and Medicago sativa,which increased by 5.74%compared with CK.Nitrogen application increased the yield by 7.83% compared with CK.The nitrogen content in root and leaf reached the highest values,which were 10.77 g·kg-1 and 48.15 g·kg-1,under the nitrogen application treatment of Pyrus sinkiangensis and Medicago sativa.Compared with CK,the increase was 5.1% and 2.2%,respectively.Under intercropping,the yield increased by17.16% and 2.93% compared with CK.These results indicated that nitrogen application and intercropping modes had significant differences in biomass and nitrogen of Pyrus sinkiangensis.In conclusion,Pyrus sinkiangensis intercropping with Medicago sativa achieved the highest yield increase benefit.Moreover,the interspecific root interaction promoted the formation of mycelium network and increased nitrogen in Medicago sativa.This has a positive effect on both legume forage and Pyrus sinkiangensis,indicating that the intercropping pattern of Medicago sativa and Pyrus sinkiangensis is the best in this study. |
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