Allelopathic Effect Of Descurainia Sophia On Wheat

In order to investigate the allelopathic potential of the volatile compounds and aqueous extracts of Descurainia sophia on the germination and seedling growth of wheat, laboratory bioassays were conducted with 8 different varieties of wheat as the acceptors and the allelopathic effects of Descurainia sophia water extracts among different organs, growing stage and concentrations were discussed. The allelochemicals from volatile oil and aqueous extracts of the Descurainia sophia were also isolated and identified. The main results were summarized as follows:1. The allelopathic effects of the volatiles released from Descurainia sophia on the seeds germination and seedling growth of 8 kinds of wheats and microbial population in soil were investigated. The chemical constituents of the volatiles were analyzed by GC-MS.The results demonstrated that the volatiles of Descurainia sophia had allelopathic effects on all test wheats, and the responses of the test wheats were significantly different. 28 major constituents were identified from the essential oil of Descurainia sophia, accounted for 64.10% of the total.The main chemical components were thymol (10.68%), a-methylfuran (10.25%), 2,4-dodecadienal(4.68%), terpenes and their oxidized derivatives accounted for 16.96% of the total,indicating that these volatiles contained potential allelochemicals, which might be related to the higher contents of terpenes and their oxidized derivatives. And allelopathic potential of these terpenes and their oxidized derivatives can be mediated by soil.2. The allelopathic effects of aqueous extracts from Descurainia sophia on 8 kinds of wheats among different concentrations were investigated. The results showed that the seed germination and the seedling growth of wheat were inhibited obviously after applying the aqueous extracts of Descurainia sophia and the inhibition rate increased as the extract concentration increasing. The stimulative effect was found by treatment with low concentration extracts for some kind of wheat, but inhibitory effect was appeared in high concentration.3. The allelopathic effects of aqueous extracts from different organs of Descurainia sophia on 8 kinds of wheats were investigated. The results showed that the inhibitory effects were both found by treatment with aqueous extracts from Descurainia sophia aerial and underground parts, the sensitivity of the wheat to the treatment differed among the variety. The allelopathic effects of aqueous extracts of Descurainia sophia aerial parts on different kinds of wheat were stronger than that of underground parts.4. The allelopathic effects of aqueous extracts from different growing stages of Descurainia sophia on 8 kinds of wheats were investigated. The results indicated that the allelopathic potential of the extracts varied among three different growing stage. The blooming stage showed significantly stronger allelopathic effects than the seed-bearing stage and seedling stage. The allelopathic effects of aqueous extracts of seed-bearing stage were stronger than seedling stage on all wheat varieties, there is no significant differences between two treatment(P>0.05).