tailieunhanh - BIOLOGICALLY ACTIVE NATURAL PRODUCTS: AGROCHEMICALS - CHAPTER 5

Từ năm 1959, nó đã được biết đến là Ailanthus altissima sản xuất một hoặc nhiều hợp chất phytotoxic. Các độc tố lớn gần đây đã được xác định là ailanthone, một thành viên của nhóm quassinoid. Trong các thử nghiệm nhà kính, tinh khiết ailanthone trưng bày hoạt động vừa phải preemergence herbicidal và hoạt động postemergence mạnh mẽ. Nó cũng có herbicidal mạnh hoạt động trong điều kiện thực địa. Trong một thử nghiệm lĩnh vực, ailanthone được phun postemergence lên cây giống của 17 loài cỏ dại và cây trồng. . | 5__ Development of an Allelopathic Compound From Tree-of-Heaven Ailanthus altissima as a Natural Product Herbicide Rod M. Heisey CONTENTS Introduction Tree-of-Heaven Ailanthus altissima Ailanthone Pre- and Postemergence Effects of Ailanthone Effects of Ailanthone on Weeds and Crops Conclusions References ABSTRACT Since 1959 it has been known that Ailanthus altissima produces one or more phytotoxic compounds. The major toxin was recently identified as ailanthone a member of the quassinoid group. In greenhouse trials purified ailanthone exhibited moderate preemergence herbicidal activity and strong postemergence activity. It also had potent herbicidal activity under field conditions. In one field trial ailanthone was sprayed postemergence onto seedlings of 17 species of weeds and crops. The lowest application rate kg ha reduced shoot biomass of six species to 10 of the control and 10 species to 50 of the control. Ailanthone is relatively nonselective but cotton yellow nutsedge and A. altissima seedlings show a high level of tolerance. Ailanthone also was tested in the field for its ability to control weeds in several vegetable crops beans tomato cauliflower corn . A marked reduction in weed population occurred for a few weeks after application but the herbicidal activity was short-lived. Nine weeks after spraying weed biomass in the most effective treatment kg ha was 60 of the weed biomass in the untreated control. Ail-anthone is rapidly degraded by soil microorganisms. It killed many of the weed seedlings present at the time of application but its herbicidal activity was rapidly degraded. As a result weeds that were not killed were able to recover and a new crop of weeds was able to emerge and grow. Ailanthone exhibits a number of the same problems that have prevented other natural products from being developed as commercial herbicides however its striking herbicidal activity under field .