The Priliminary Research Of Herbicidal Activity Of Cephalotaxus. Sinensis

It was significant for the creation of novel pesticide with our independent knowledge property right to search new herbicidal plants, and guided by bioassay, to isolate and identify new compounds from plants with new structure and strong herbicidal activity. It is an obvious resource advantage to research botanical pesticide in western of China for its abundant plants resources. Zhang Xing and Feng Jun-tao etc have studied the insecticidal and antifungal activities of many plants in this area. In order to find new herbicidal plants, herbicidal activities of 39 species of plants were tested and the herbicidal activity of Cephalotaxus. Sinensis was preliminary studied. The results are as following:Firstly, The herbicidal activity of 39 species plants under 22 families, 35 genus were determined by the seeds germination of Sorghum vulgare P., Cucumis sativus L., Triticum aestivum L. and Brassica campestris L.. The results showed that inhibitory rates of 33 species of plants were more than 70% at least to one species of crop seeds. The inhibitory rates of R. palmatum, M. neglecta, M. verticillata and R. communis against young roots of the 4 species of crop seeds were more than 70%. The inhibitory rates of Cephalotaxus. Sinensis and P. acinosa not only against young roots, but also against young buds of the 4 species of crop seeds were more than 70%, which provided the evidences for further research of plants derived the herbicidal chemicals.Secondly, the results of test of herbicidal activity showed that the inhibitory rates against young roots and young buds of the 90% alcohol extract from Cephalotaxus. Sinensis under the concentration of 80mg/ml. And the 19 species plants are Sorghum vulgare,, Cucumis sativus, Brassica campestris, Triticum aestivum, Brassica oleracea, Lactuca sativa, Raphanus sativus, Lycopersicon esculentum, Amaranthus paniculatus, Trifolium repens, Medicagos sativa, Abutilon theophrasti, Chenopodium album, Avena fatua, Descurainia Sophia, Amaranthus retroflexus, Echinochloa crusgalli, Veronica didyma and Capsella bursa-pastoris. When the concentration decreased to 10mg/ml, the inhibitory rates against young roots only to Chenopodium album and Trifolium repens beyond 70%.Thirdly, the active ingredients of Cephalotaxus. Sinensis have been separated with bioassay-direction. The results showed that the herbicidal active ingredients mainly existed in chlorin extract and benzene extract because the inhibitory rates of both against young roots and young buds to Sorghum vulgar, Amaranthus paniculatus and Amaranthus retroflexus were more than 90%under the concentration of 10mg/ml. The benzene residue was separated with chromatography and TLC etc methods. And a compound A was isolated from it. The structure of A was identified as β-sitosterol. Under the concentration of 10mg/ml, the inhibitory rates of β-sitosterol against young roots of Amaranthus retroflexus was 26.2% and against young buds was 23.7%.Fourthly, the selectivity of the extract from Cephalotaxus. Sinensis to the roots of Triticum aestivum and Avena fatua has been studied. Under the laboratorial conditions, when the length of roots of Triticum aestivum was 0-1cm and that of Avena fatua was 2-3cm, the inhibitory of the extract against young roots were higher than that in other length. The inhibition of the extract against young roots to Triticum aestivum was decreasing with its length increased. On the contrary, that to Avena fatua was increasing with the length of its roots increased. And the inhibition to roots of Avena fatua were stronger than that to roots of Triticum aestivum.