Preliminary Study On Isolation And Mechanism Of Herbicidal Active Fractions From Pestalotiopsis Microspora

It is well known that the compatible green pesticide with environment has been the inevitable direction of the development of pesticide formulation in the contemporary era, it is one of the important approach on research green pesticide that screen active pesticide substances or chemoinformatics in millions of crude compounds. The former research from our Lab showed that the crude extracts from Pestalotiopsis microspora had a good deactivation to many weeds. Since it can keep effectiveness of deactivation to weeds for a long time, crude extracts from Pestalotiopsis microspora have a quite potential to be a real biology herbicide. In this study, on the basis of solid and liquid culture media for toxin-producing ability of Pestalotiopsis microspora, toxin-producing conditions were researched. The herbicidal active fractions were separated and herbicidal mechanism was studied to private some theories for the high-performance exploitation of toxin.The results are as follows:1. Liquid culture and solid culture were compared and the results showed that solid culture had the advantages of short-cycle, strong herbicidal activity, low-cost and so on. so the solid culture wss the most suitable way of toxin-producing for P. microspora.2. The P. microspora fermentation conditions had been optimized. P. microspora, which was inoculated into millet or corn residue and trained at 30℃for 8 d in darkness, will own the strongest herbicidal bioactivity. It was also found that glucose could dramaticly elevate the production of toxin.3. It could be found that the herbicidal bioactivity of its crude toxin extracted by using ethyl acetate was the strongest among all tested extraction solvent and methods. The best developing agent of TLC is Et Ac∶igarine=1∶1 or Acet∶igarine=2∶1. The toxin was separated by using CC and HPLC then a high herbicidal active fraction was isolated.4. The stability of bioactivity of toxin to Digitaria sanguinalis was tested by high temperature. The results showed that the toxin remained bioactivity through being treated 6 hours at 80℃. But long lighting could reduce the ability of herbicidal.5. The effect on inhibition of seed germination was determined and the MDA content, superoxid anion radical content, Hill activity, electric conductivity, the chlorophyll and β-carotene content, the loss of water content were examined. The results showed that the effects on the MDA content, electric conductivity, superoxid anion radical content, the relative loss of Hill activity under illumination and so on were higher than themselves under darkness. So it indicated that lights had some effects on the herbicidal activity of toxin from Pestalotiopsis microspora.