Studies On The Actinomycetes With Agricultural Activity In Soil

The primary studies isolated of actinomycetes from 67 sample in soil.408 strains of actinomycetes were obtained. From the screening of the insecticidal, fungicidal and herbicidal activities ,We found 2 strains of actinomycetes numbered 54^# and A₂C ,the metabolites of which had the strong fungicidal activities. The main results are as follows: 1.The results of mycelium growth rate showed that the value of EC₅₀ of the fermentation products of 54^# against Macrophoma kuwatsukai, Botrytis cintrea, Sclerotinia sclerotiorum Becry and Botryis cinerea Pers were 45.02μg/ml,59.71μg/ml,51.54μg/ml,59.37μg/ml, respectively.the value of EC₅₀ of the fermentation products of A2C against Alternaria solani, Botrytis cintrea and Gibberella zeae were 67.25μg/ml,40.87μg/ml,45.19μg/ml , respectively.The results of spore germination proved that the value of EC₅₀ of the fermentation products of 54^# and A₂C against Exserohilum turcicum, Alternaria longipes and Fusarium oxysporium were 169.95μg/ml,206.52μg/ml,206.52μg/ml and 104.12μg/ml,264.47μg/ml,305.05μg/ml. The results of pot tests against Blumeria guaminis indicated that the fermentation products of 54# and A₂C exhibited 78.8% and 90.3% protective efficacy, 71.7% and 87.0% therapeutic efficacy . The field trails results showed that the control efficacy of the fermentation products of 54^# against Pseudoperonospora cubensis and Fulvia fulva were 55.6% and 74.8%, the fermentation products of A₂C against Pseudoperonospora cubensis and Fulvia fulva were 87.8% and 59.8%. The results of tests of the herbicidal activity showed that the value of EC₅₀ of the fermentation products of 54^# against the caulis of Amaranthus and Echinochloa were 106.07μg/ml and 91.05μg/ml. 2. The test of stabilities indicated that the secondary metabolites of 54^# and A₂C strains were stable to acid, alkali ,temperature,illumination,ultraviolet radiation. when subculture ten generations,The fungicidal activity of secondary metabolites of 54^# and A₂C strains did not alter. 3. By means of observation on substrate mycelium, aerial mycelium, spore and sporothrix, Cultural characteristics, Biochemical and physiological characteristics, 54^# and A₂C strains were primarily identified as a variety for which the name S.graminearus emm.var. , S. cinereohygroscopicus.var., respectively. 4. Using 54# strain as an original strain, mutagenized with ultraviolet, 159# strain was obtained. This strain had a double activity as high as 54# strain against Bacillus subtilis. And it had good stabilities. The activity had not greatly altered either by several subcultures or any other temperature, acid and alkali, illumination and ultraviolet radiation.