| China owns the most abundant bamboo resources in the world and bamboo leaves resources have not been utilized reasonablely.The research on allelopathy of the bamboo leaves can offer a new way for chemical utilization of them and it is a good basis to develop new bioherbicide. The allelopathy of the bamboo leaves from 83 species were evaluated and the toxicity of the bamboo leaves with strong activities from 6 species were tested in the paper. Bambusa ventricosa leaves extracts were isolated by modern separation techniques under bioactivity-guided. The main results were as follows:1. The effect of the bamboo leaves from 83 species in 22 genuses on the growth of radish seedlings were evaluated through the method of grinded plant tissue powder mixed with agar (PPA). The results showed that most of the tested bamboo leaves showed inhibitory effect under the concentration of 2g·L-1, and the inhibitory effect was higher on root than on hypocotyl and fresh weight. Of the 38 species bamboo leaves from Phyllostachys and Bambusa,27 species inhibited root length by 50%. Tested species from Pleioblastus and Dendrocalamus showed strong inhibitory activity on radish root growth. Twenty-two of the 30 species bamboo leaves from the other genuses also had strong inhibitory activity on root. Eight species of bamboo, namely Phyllostachys glauca,Phyllostachys bambusoides, Bambus multiplex, Pleioblastus yixingensis, Pleioblastus china f.hisauchii, Dendrocalamus brandisii, Sasa argenteastriatus and Ferrocalamus strictus, demonstrated strong herbicidal activity. The results suggested that bamboos have strong allopathic activities and the leaves were one of the allelopathic organ in bamboo.2. The phytotoxic effects on root growth of 6 selected bamboo leaves (Bambusa multiplex, Pleioblastus yixingensis, Phyllostachys glauca, Ferrocalamus strictus, Dendrocalamus brandisii, Phyllostachys bambusoides) in the plant models (Cynodon dactylon, Agrostis stolonifera,Poa annua,Trifolium pratense,Lactuca stiva) were investigated.The significant dose-response relationships for phytotoxic effects were observed.The EC50 values were ranged from 1.0937 g·L-1 -3.6250 g·L-1 for Bambusa multiplex,2.7381g·L-1 -5.9772g ·L-1 for Pleioblastus yixingensis,1.3975g·L-1 -5.3336g·L-1 for Phyllostachys glauca, 1.6306 g·L-1 -6.4083 g·L-1 for Ferrocalamus strictus,0.9319g·L-1 -3.4198g·L-1 for Dendrocalamus brandisii, and 1.6142g·L-1 -3.8558g·L-1 for Phyllostachys bambusoides,respectively.6 bamboo leaves have strong phytotoxic effects on root growth of the plant models. The inhibitory activity can destroy the root and has bad effect on the whole plant growth.3. A bioactivity-guided isolation was designed to isolate allelochemicals from the leave of Bambusa ventricosa.The ethyl acetate fraction and N-butanol fraction showed strong herbicidal activity against Lactuca stiva and Agrostis stolonifera.The ethyl acetate layer was subsequently chromatographed and 1 fractions was confirmed a strong phytotoxic effect.The fraction was analysed by GC-MS, six compounds was determined, they were 2-methoxy-4-vinylphenol,4-hydroxybenzaldehyde,3-hydroxy-4-methoxybenzoic acid,coniferyl alcohol,syringic acid and 4-hydroxy-3-methoxycinnamic acid. The content of each compound were 0.84%,0.66%,2.88%,2.25%,2.92%,3.21%, respectively. The result of activity showed that the compounds had no significant influence on root growth of Lactuca stiva and Agrostis stolonifera. The active components should be studied further. |
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