Study Of Biological Nitrogen Fixation Efficiency Under Intercropping Of Two Legumes And Young Korla Fragrant Pear

In order to study the contribution and mechanism of legume forages to the agronomic characters,nitrogen fixation and nitrogen transfer formation of young Korla pear under root interaction,this study took legume forages and pear trees as the research objects,and adopted a completely random block design: 2(nitrogen level)×4(root barrier method)×2(species combination)× 3(repeat),two nitrogen levels were set,nitrogen application(N1),no nitrogen application(N0),four root barrier treatments,no barrier treatment(N),30 μ m nylon mesh barrier(TN),5 μm nylon mesh barrier(FN),plastic membrane barrier(PS).With plastic film barrier as the control,two kinds of legume were alfalfa(Medicago sativa)and hairy vetch(Vicia villosa),2 year old korla sweet pear(Pyrus sinkiangensis Yu).The growth status of pear tree,alfalfa and hairy vetch as well as nitrogen fixation,nitrogen fixation rate and nitrogen transfer rate were measured and analyzed under different intercropping systems in order to deepen the understanding of the interaction mechanism between legumes and pear species.The main research results are as follows:(1)different ways of blocking,alfalfa,hair Chinese trumpet creeper plant height,the ground biomass,root biomass in root interactions(don’t block,30 microns nylon net block)under the conditions of all present a low,with the root system is not cut off(5 microns nylon nets,plastic blocks)than for alfalfa and hair growth conditions of Chinese trumpet creeper.Nitrogen application had no significant effect on plant height and overground biomass of alfalfa and hairy vetch,but nitrogen application increased the underground biomass of the two legumes.((2)The nitrogen fixation efficiency and nitrogen transfer efficiency of alfalfa and hairy vetch reached the maximum value under the condition of root interaction(no barrier),which was beneficial to improve the nitrogen fixation efficiency and nitrogen transfer efficiency of alfalfa and hairy vetch compared with the root interaction(5 μ m nylon net barrier and plastic film barrier).After nitrogen application,the nitrogen fixation efficiency and nitrogen transfer efficiency of alfalfa and hairy vetch decreased significantly.Nitrogen application could cause young korla sweet pear to obtain more nitrogen from the soil and reduce the dependence on the nitrogen fixation efficiency and nitrogen transfer efficiency of legumes.(3)The correlation analysis found that the nitrogen fixation rate and nitrogen fixation amount of vetch and alfalfa were positively correlated with the number of root nodules,root nodules weight,hemoglobin and nitrogenase activity.Correlation analysis showed that the rate and amount of transfer nitrogen of alfalfa and hairy vetch were positively correlated with the infection intensity of AM fungus,the infection frequency of AM fungus and the density nitrogen of mycelia in the soil.(4)Compared with the nitrogen fixation efficiency,nitrogen transfer efficiency,pear height growth and single growth of smooth vetch under alfalfa and hairy vetch intercropping with young vetch,young vetch intercropping with alfalfa was better than that with hairy vetch.