Evaluation of dominant allelopathic weed through examining the allelopathic effects of four weeds on germination and seedling growth of six crops

摘要

Leaf aqueous extracts were used to examine the allelopathic effects of Melilotus indica, Medicago polymorpha, Elusine indica and Fumaria indica at four concentrations (10, 20, 30 and 40% W/V) on germination percentage, radicle and hypocotyl growth of s ix crops, namely Triticum aestivum , Hordeum vulgare, Medicago sativa, Trifolium spp., Raphanus sativus and Trigonella foenum-graecum. All weed extracts showed pronounced inhibitory effect on germination and seedling growth of tested crops, however inhibition was not consistent over studied parameters. Weeds exerted different allelopathic effects on test crops. Fumaria indica exhibited a significant negative effect on germination of all tested species at 20, 30 and 40% aqueous extracts, followed by Elusine indica and Medicago polymorpha , and Melilotus indica at 10% concentration level. Melilotus indica halted the hypocotyl growth of tested crops at 10 and 20% aqueous extracts, followed by F. indica at 30 and 40% dosage. Radicle growth of all recipient species was also stunted under the aqueous extract of M. indica at 20, 30 and 40%, followed by Medicago polymorpha except 10% concentration. Elusine indica showed negative effects on hypocotyl growth at higher concentrations as compared to Medicago polymorpha , whereas radicle growth was not affected under different aqueous extracts of E. indica . Leaf debris method was used in greenhouse to further authenticate the allelopathic effects of dominant allelopathic weed viz., Melilotus indica at four concentrations (0, 25, 50 and 75 g per 300 g of soil) on germination percentage, shoot and root length of four crops, namely Medicago sativa, Trifolium spp ., Hordeum vulgare and Triticum aestivum. Powdered leaf debris of M. indica mixed with clay loam soil appeared to have strong allelopathic inhibition under higher concentrations on germination and shoot growth of Medicago sativa and Trifolium spp. as compared to Hordeum vulgare and Triticum aestivum , whereas inhibitory effects were more pronounced on Trifolium spp. and Triticum aestivum , in terms of their root length. Hence, M. indica proved a strong allelopathic weed that should be removed from field to avoid harmful effects during early growth stages of tested crops. Moreover, it is recommended that all these species be phytochemically examined for their allelopathic potential and possible development of environmental safe bio-herbicides to control weeds.