Screening Of A Mycoheribicide For Echinochloa Crus-galli In The Rhizosphere Of Allelopathic Rice And Studies On The Growth Characteristics

As a special germ plasm resource, alleiopathic rice can form a microenvironment in the the rhizosphere. So it is important for studying screening herbicide. In this paper, different kinds of microorganisms were isolated from the rhizosphere of alleiopathic rice. Using the model of RSA(relay seeding in agar), a strain A1 is screened from them. And the A1 strain is identified as Aspergillius nige. An optimum medium was obtained through single factor tests and optimization tests. And at last we analyzed the chemical components of the A1 fermentation solution. The results as follows:1,151 strains of different kinds of microorganism were isolated from the rhizosphere of alleiopathic rice. Using the model of RSA(relay seeding in agar) and the IR(inhibitory rate), a strain A1 is screened from 151 different kinds of strains. It has shown that the inhibitory rate of the A1 cultured solution is 100%, and it is 55．4% when the cultured solution was diluted 200 times.2,In the paper, colony characteristics, optic microscopic observation the strains and the biological features of the A1 strain were studied. The A1 strain is identified as Aspergillius nige. Its growth temperature was 25-35℃, the optimum original pH of spore budding mycelium growth was about 6．5．3,An optimum medium was obtained through single factor tests and optimization tests. During the research, we have found that the strains A1 has grown well in the medium of PDA. C, N, P and S is the essential element for the A1 growth. K and Mg can facilitate the growth of A1．The best organic nitrogen source is yeast power, and the best carbon source is corn flour. The optimal carbon-to-nitrogen ratio is 40:1．The most moderate breeding condition for fermentation is: temperature 32℃, the rocking bed velocity is 180r/min, the original pH for medium is 4．5, 2% yeast power, 2% corn flour.4,Systematic pre-experiment showed that the A1 fermentation solution contain amino acid, protein, polypeptide, organic acid, saponin, tannin, phenol, quinine, inner ester, coumarin, sterol, triterpene. By GC/MS, the chemical components of the volatile A1 fermentation solution contains organic acid, alcohol, ester, phenol, terpenoid, aldehyde. And terpenoid(38．48%) and alcohol(43．36%) is in the majority. And the chemical components of the A1 fermentation solution contains phenols or quinines, alkane, ester, organic, and alkane(23．63%) is in the majority. By HPLC, the chemical components of the A1 fermentation solution contains critric acid, lactic acid oxalic acid. The research showed that there were different kinds of chemical components in the A1 fermentation solution and the components were complex.And it had been reported that some of the chemical components were also isolated from the rhizosphere of alleiopathic plants. For example Butylated Hydroxytoluene, Phenol,2,6,-di-tert-butyl-, C₁₈ H₃₈ , C₂₀ H₄₂ , C₂₁ H₄₄ , C₂₃ H₄₈ and etc.Finally, the main issues problems of the chemical components of A1 fermentation solution associated with allelopathy were further discussed in this paper.