Preparation Of Biochar-PGPR Microbial Agent And Facilitation Of Rice Development In Seedling Stage

In order to satisfy the ever-increasing grain demand with the ever-increasing population,excessive fertilizers were used to supply soil fertility and ensure grain reserves and yield.However,the excessive application of fertilizer in a long term may not only decrease the quality of agricultural products,but also cause a series of environmental pollution problems.Therefore,as a kind of environment-friendly fertilizer microbial agent came into our horizon gradually.In 1950s,a kind of bacteria was found that could influence the plant development by producing IAA(Indole-3-acetic,auximone),which is named IAA-producing bacteria.Bacillus Subtilis 168 is widely used as a type strain of IAA-producing bacteria.Biochar can be an excellent carrier because it is simple to make and has a wide range of sources.Meanwhile,the high content of nutrient and porous texture of biochar may help PGPR colonizing on it.Thus,for agricultural production,microbial agent can not only promote plant growth,but also be an economical,efficient and high-yield choice.However,the identification and characterization of key genes or enzymes in IAA biosynthesis are rarely studied,and it is precisely because biochar comes from a wide range of sources and which kind of biochar is the better carrier for IAA producing bacteria and the effect of microbial agents prepared from this biochar on rice growth is not well understood.This thesis began with designing the primers of functional genes of IAA production bacteria to quantification IAA production bacteria accurately in soil.And then,screened appropriate biochar as carrying materials to preparation biochar-PGPR microbial agent and finally investigated the effect of biochar-PGPR microbial agent to the rice development.The mainly findings of this paper are as follows:(1)Designing the primers of functional gene of the strain Bacillus Subtilis 168,bioA,(bioF:5’-TCAATCTTCAAGGCTCGTAACC-3’/bioR:5’-ATGACTCATGATTTG ATAGAAAAAAGTAAA-3’)via collecting original sequence,comparing high conservative region,controlling primer quality,sequencing cloning,comparing of BLAST and verifying the property of amino acid transaminase by translation comparing.It will catalyze in IPA pathway when tryptophan is transformed to indolepyruvic acid,and it gave a technique foundation for the follow-up work of quantifing functional genes of 168.(2)We conclude that bamboo biochar is the most appropriate carrying material among all the 7 kind of biochar:bamboo biochar,peanut shell biochar,maize straw biochar,rice straw biochar,rice husk biochar,coco shell biochar and pine wood biochar through researching these biochar-PGPR microbial agent’s influence on the shelf live of Bacillus Subtilis 168 and IAA production.The abundance of functional genes,16S rRNA genes relative abundance and IAA production were used to prove our results..(3)In order to study the effect of microbial agent which was screened by the second experiment on the growth of rice,we added it into soil and observed through a 21 day-cultivation.Finally,we found that microbial agent can increase the shoot and root extension significantly in the rice seeding stage and promote the differentiation of lateral root and leaves significantly,and this facilitation was better than applying biochar and Bacillus Subtilis 168 respectively,even though there was no significantly increase of IAA production in soil.