This experiment was conducted in order to determine if Persian clover (Trifolium resupinatum) and Berseem clover (Trifolium alexandrium) contained water-soluble and methanol-soluble constituents that could affect the seedling growth of four test species; namely, Amaranthus retroflexus, Convolvulus arvensis (field bindweed), Secale cereale, and Sinapis arvensis (wild mustard). The above-ground tissues of the Persian and Berseem clover plants were collected during the vegetative growth stage and oven-dried. Three concentrations of aqueous and methanolic extracts were used at full-strength (33.3 g L -1 ), half-strength (16.7 g L -1 ), and quarter-strength (8.3 g L -1 ). Distilled water was used as the control.The weed seeds were placed in Petri dishes containing the legume extract or distilled water (control). The seedling growth of the weed species declined with the increasing concentration of the clover extracts. Wild mustard exhibited the highest sensitivity to both the legume extracts. Compared to the aqueous extract, the methanolic extract caused a greater decline in the seedling growth of the weeds. Berseem clover was the stronger inhibitor of the weed seedling growth, as compared to Persian clover. Therefore, the amounts of allelochemicals present might differ in these two clover species. Field bindweed showed the least sensitivity to both the legume extracts. Field bindweed showed more tolerance to the allelochemicals produced by the clover species.
The 'equal-compartment-agar-method' was employed to evaluate four allelopathic activity wheat cultivars on whole plant, root and shoot length and plant dry weight of four weed species. Wheat cultivars were included Niknejad and Shiraz (more competitive cultivars); Tabasi and Roshan (less competitive cultivars). In this study used four weed species (Secale cereale L., Avena ludoviciana L.: monocotyledon, Convolvulus arvensis L. and Vicia villosa L.: dicotyledon). Results showed that the allelopathic activity of wheat was associated with number of wheat seedlings and wheat cultivars. Results demonstrated that the whole plant and root length of weed species were significantly reduced in the presence of wheat cultivars. The degree of weed growth inhibition was depended on the number of wheat seedlings. All of the cultivars and densities caused promotion of dicot shoot length. Results indicated that the length of whole plant (-30.22%) and root (-57.74%) of C. arvensis and shoot length (-13.24%) of S. cereale had the highest sensitivity. None of factors had significant effect on plant dry weight of weed species.
Laboratory studies were conducted to determine the seed germination of Amaranthus retroflexus, Convolvulus arvensis, Secale cereale and Sinapis arvensis as affected by water-and methanol-soluble constituents of Persian and Berseem clovers. Aboveground tissues of the clovers were collected during flowering stage and dried. Three concentrations of aqueous and methanolic extracts were used: full-strength (33.3 g L(-1)), half-strength (16.7 g L(-1)) and quarter-strength (8.3 g L(-1)). The weed seeds were placed in petri dishes contained the legume extract, or distilled water (control). Percent seed germination was taken after a week. In general, seed germination of the weed species declined progressively with increasing concentration of the clover extracts. It was found that wild mustard exhibited the greatest sensitivity to both the legume extracts. Compared with aqueous extract, methanolic extract caused more decline in seed germination of the weeds. In addition, compared to Persian clover, Berseem clover was stronger inhibitor of seed germination. Therefore, the amounts of allelochemicals may be different in these clovers. Field bindweed showed the least sensitivity to both the legume extracts. Therefore, field bindweed had probably more tolerance to the allelochemicals produced by the clover species.
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