| Alfalfa (Medicago sativa L.), known as the king of the cultivated forage legume, plays an irreplaceable role in animal husbandry. With the development of large-scale farming in our country, alfalfa yield is insufficient. In order to improve alfalfa production, chemical fertilizers and pesticides were used, thus excessive application of chemical fertilizers and pesticides bring a series of environmental issues. How to improve alfalfa yield while reduce environmental pollution is a urgent task. Lactic acid bacteria (LAB) with their metabolites, as a safe and environmental-friendly new probiotics, has a potential application value in improving the yield and quality of alfalfa.Five strains of lactic acid bacteria including L.plantarun IMAU80065, L.plantarun IMAU70101, L.plantarun IMAU70088, L.plantarun IMAU11048 and L.casei IMAU10048, having a good inhibitory effect of pathogenic fungi, were obtained from previous study. In present study, bacterium suspension was prepared by inoculating these five strains of lactic acid bacteria in liquid medium for 48 hours under 25℃, then sprayed in alfalfa leaf and soil. We obtained following results by determining alfalfa growth index, yield, nutrition index, soil nutrient and the change of soil microorganism.(1) Treatment with LAB and their metabolites significantly enhance the quality of alfalfa and promote alfalfa growth. We showed that treatment with LAB and their metabolites significantly increased the fifth stubble plant height(18.44%), stem diameter (29.55%), plant branch(7.21%). Compared to the control, the height of the sixth stubble plant in LAB-treatment group and metabolites-treatment group were increased with 27.12% and 5.93%, respectively.(2) Treatment with LAB and their metabolites significantly enhance the yield of alfalfa. Compared to the control, the yield of the fifth stubble fresh grass was increased with 40.98% in LAB-treatment group. In LAB-treatment group and metabolites-treatment group, the yield of the sixth stubble fresh grass were increase with 20.40% and 12.15%, respectively.(3) Treatment with LAB and their metabolites (especially treatment with LAB) improve the quality and the utilization value of Alfalfa. Compared to the control, in LAB-treatment group, the crude-protein content and relative feeding value of the sixth stubble alfalfa was increased with 2.00% and 10.00%, respectively.(4) Treatment with LAB and their metabolites improve soil environment, soil nutrient and promote the growth of beneficial soil microorganism, as well as inhibit the growth of harmful fungi. Treatment with LAB metabolites enhance the content of organic matter and available phosphorus in soil of 14#, with an increase of 6.00% and 1.00%, respectively. Compared to the control, treatment with LAB increased the soil available phosphorus by 90.10%, the total number of soil bacteria were increased with 37.50% and 17.70% in LAB-treatment group and metabolites-treatment group, respectively, the total number of actinomyces were increased with 42.00% and 38.64% in LAB-treatment group and metabolites-treatment group, respectively,, while the number of fungi were reduced by 43.59% and 45.45% in LAB-treatment group and metabolites-treatment group, respectively. |
