Allelopathic rice for Echinochloa crus-galli control

Recent research has shown promising allelopathic potential in rice germplasm. Accessions with allelopathic potential have different origins and different stages of improvement indicating allelopathic potential to be widespread in the germplasm. At IRRI, held experiments were conducted in the 1995 dry and wet seasons to find plant interference potential against E. crus-galli in 111 rice cultivars. The dry season results showed that 11 cultivars suppressed weed growth (dry matter) by more than 50% and 20 cultivars by 40-50%. In the wet season, 21 cultivars were able to suppress weed growth by more than 50%, whereas 22 cultivars had a 40-50% reduction. To distinguish allelopathy from competition, laboratory experiments were conducted using the same cultivars as in the field experiment. E. crus-galli was seeded in plant boxes where seven day old rice seedlings were established. Ten days later root and shoot length off. crus-galli was measured. Results showed that cultivars able to suppress this weeds in field experiments were also able to decrease root elongation in the laboratory. These results indicate that some rice cultivars have strong allelopathic effect against E, crus-galli.