Study On The Growth Promotion Of Eggplant By Amino Acid-enhanced Bacillus Megatherium

In recent years,vegetable farmers unilaterally pursue high yields of facility vegetables and unreasonably apply a large number of chemical fertilizers,resulting in a series of problems,such as vegetable quality and soil ecology,which have attracted wide attention of scholars.Phosphorus-solubilizing microbial agents have the characteristics of promoting plant growth,improving soil ecological environment and releasing fixed nutrients in soil.They are widely used in environment and agriculture in recent years.Our group had confirmed the phosphorus dissolving effect of Bacillus megaterium on eggplant and solanaceous vegetables at previous.Compared with conventional fertilization,the available phosphorus of soil increased by 7.9% with the combination of reduced fertilizer and microbial inoculum,while there are few research on the effect of amino acid-fortified bacteria on promoting growth and dissolving phosphorus.Accordingly,in this study,Bacillus megaterium and eggplant seedlings were taken as research objects.Through simulation experiments and field experiments,the effects of different amino acids on the secretion of indole acetic acid by Bacillus megaterium,the mechanism of growth promotion of eggplant seedlings,the effect of phosphorus solubilization from different phosphorus sources and the application of amino acids and Bacillus megaterium to facility eggplants were studied.Base amino acid enhanced the growth promoting effect of Bacillus megaterium on eggplant seedlings,and studied the effects of microbial inoculum on soil nutrients and microbial diversity of facility eggplant at different growth stages,in order to find the suitable period for application in facility vegetable production.The main results are as follows:(1)The mechanism of different amino acids stimulating the secretion of auxin by Bacillus megaterium was elucidated by liquid shaking flask test,and the effects of different amino acids on IAA secretion by Bacillus megaterium were explored.From 19 amino acid screening tests,it was found that methionine,glutamic and proline could significantly promote IAA secretion of the strain,which increased 118%,55.93%,41.73% and 40.25% respectively compared with the control.(2)Through hydroponic experiment,the synergistic effect of optimum amino acid-fortified Bacillus megaterium on eggplant seedling growth was clarified,and the synergistic effect of optimum amino acid-enhanced Bacillus megaterium combination on eggplant seedling growth was clarified.Among the four amino acids,tryptophan and proline significantly enhanced the root weight and chlorophyll of Bacillus megaterium seedlings,which increased 36.67%,24.52% and 7.65%,7.13% than that of single inoculation.Glutamic acid,cystine,tryptophan and methionine significantly promoted IAA secretion of Bacillus megaterium,which was 64.1% and 172% higher than that of single inoculation.Proline significantly promoted IAA secretion in eggplant root,which was 121% higher than that in single plant.(3)Pot experiments with vermiculite further clarified the effect of mixed amino acids on enhancing the growth of eggplant seedlings with Bacillus megaterium.Under inorganic phosphorus and organic phosphorus conditions,the biomass and root weight were increased by 42.50%,46.12% and 60%,49.17% respectively.Soil available phosphorus increased by 47.59% and 45.87%;alkaline phosphatase activity increased by 161% and 5.69%;plant phosphorus uptake increased by 62.12% and 59.75%;hizosphere soil IAA content increased by 25.71% and 0.97%;biomass increased by 82.52% and 83.99%;root weight increased by 57.58% and 50%,soil available phosphorus increased by 55.59% and 33.91%,alkaline phosphatase increased by 95.88%(inorganic phosphorus);plant phosphorus accumulation increased by 105.79% and 161.63%;IAA content in rhizosphere soil increased by 11.04%(inorganic phosphorus).(4)Through field experiments,the suitable period of applying amino acid and microbial inocolum on facility eggplant was determined.From the synthetical effects of yield increase and nutrient environment of eggplant,the effect of applying microbial inocolum on various indicators,the second stage is outstanding.Therefore,in the production of facility eggplant,the suitable period for applying microbial inocolum in second stage can be recommended.In conclusion,this study identified the effects of mixed amino acids and different kinds of amino acids on the growth of eggplant seedlings under different forms of phosphorus sources,and provided important theoretical basis and technical support for the appropriate period of microbial agent application in the practical production of protected eggplant.