Potential allelopathic effects of rice plant aqueous extracts on germinationand seedling growth of some rice field common weeds

摘要

Given the increasing emphasis on sustainable agriculture, andconcerns about the adverse effects of extensive use of farm chemicals, research attention is now being focused on reducing thedependence upon synthetic herbicides, and finding alternativestrategies for weed management. Allelopathic properties of cropplants may allow us to use lower amounts of herbicides with benefits for the environment and human health. Considering theseaspects, the present study was conducted to investigate the allelopathic effects of six selected rice varieties (WITA-3, WITA-4,WITA-12, Woo-Co, Fukuhibiki and Kalizira) collected fromBangladesh Rice Research Institute (BRRI) on seed germinationand seedling growth of five weed species; Echinochloa crus-galli,Cyperus difformis, Cyperus iria, Fimbristylis milliacea and weedyrice. The aqueous extracts of all the rice cultivars caused inhibitory effects on seed germination and seedling shoot-root length ofall the weed species. However, the inhibitory effects of differentrice varieties varied significantly based on the differences of weedspecies and weedy rice found to be the least afFected compared toother weeds. WITA-12 resulted about 50% germination inhibition,25% shoot length reduction and 23% root length reduction respectively compared to control. On the basis of average percentageinhibition, rice varieties ranked in order; WITA-12>WITA-4>Fukuhibiki>Kalizira>Woo-Co>WITA-3. Our results suggestedthat there is a possibility of developing a new ecological weedmanagement strategy using rice cultivars with higher allelopathicpotentials. This means breeding of rice cultivars with higherallelopathic potential may provide natural and sustainable weedmanagement options for rice growers.