Allelopathic Potential in Rice Germplasm Against Ducksalad, Redstem and Barnyard Grass

Abstract

Summary Of 17,279 rice accessions or varieties from 110 countries in the USDA-ARS rice working collection, about 12,000 accessions in the rice collection have been evaluated for allelopathy to ducksalad (Heteranthera limosa[Sw.] Willd.) and about 5,000 have been evaluated for allelopathy to redstem (Ammannia coccinea Rottb.) and barnyard grass (Echinochloa crus-galli[L.] Beauv.). A total of 412 rice accessions were identified in field tests in 1988, 1989 and 1990 that had an area of allelopathic activity > 10 cm to ducksalad and 145 accessions that had the same area of activity to redstem. A total of 94 accessions demonstrated apparent allelopathic activity to barnyard grass. The rice accessions that showed allelopathic activity in the field had 2-3 times more root biomass than cultivars that did not show allelopathic activity. In barnyard grass infested plots the grain yield reduction of rice accessions that demonstrated allelopathy activity was about 37% as compared to a 60 to 68% reduction in grain yield of non-allelopathic accessions. Chromatograms of allelopathic and non-allelopathic accessions fall into two types, one that is represented by the allelopathic PI 312777 and the other by the non-allelopathic cultivar ‘Rexmont’.