Potential Allelopathic Candidates for Land Use and Possible Sustainable Weed Management in South Asian Ecosystem

Weed management is one of the significant challenges of field crops since weeds pose a remarkable threat to crop productivity in South Asian countries, including Bangladesh. Allelopathy, a phenomenon whereby secondary metabolites produced and released by one plant species influence the growth and development of other species can be exploited in sustainable management. The focus of this study was to evaluate potential allelopathic plant species which can be further explored as alternatives to synthetic herbicides or incorporated as part of integrated weed management in sustainable agriculture. Two hundred fifty-two plant samples from 70 families were collected from Bangladesh and evaluated with the sandwich bioassay. Thirty-one percent of the samples showed significant allelopathic potential on lettuce radicle elongation. Among the species that showed substantial inhibition, more than 7% of the samples showed higher inhibition (HI) and 25% showed moderate inhibition (MI) on lettuce radicle. Fruit pulps of Couroupita guianensis (95.4%), fruits of Phyllanthus emblica (95.4%), and Acacia concinna (95.4%) showed the highest inhibition on lettuce radicle elongation. In contrast, the leaf of Bombax insigne had growth promoting activity by stimulating radicle (23%) and hypocotyl (80%) elongation of lettuce seedlings. This result suggested that the species with significant plant growth inhibitory potential may play a vital role as an alternative to the increasing use of synthetic herbicides for sustainable weed management in agricultural land.