Parthenium management through aqueous extracts of Alstonia scholaris

摘要

Phytotoxic effect of aqueous leaf and bark extracts of Alstonia scholaris (L.) R. Br. was investigated against parthenium weed (Parthenium hysterophorus L.). In a laboratory bioassay, carried out in 9-cm diameter Petri plates, 2–10% aqueous extracts of fresh leaves significantly reduced germination of parthenium seeds from 30-80%. Seedling growth in terms of root and shoot length, and fresh biomass, was also significantly reduced by all except 2% extract concentration. Bark extracts of same concentrations proved less toxic resulting in an insignificant reduction in germination. Generally, the effect of bark extract on seedling growth was also insignificant. In foliar spray bioassay, three sprays of 50% and 100% w/v (on fresh weight basis) leaf extracts were carried out on 15 days old parthenium plants with 5 days intervals. A significant reduction in root and shoot biomass was recorded due to 100% foliar spray, after 2 week growth of the first spray. The present study concludes that aqueous leaf extract of A. scholaris contain potent herbicidal constituents for the management of parthenium weed.