THE INFLUENCE OF RICE PLANT TYPE ON THE EFFECT OF WEED COMPETITION ONORYZA-SATIVA AND ORYZA-GLABERRIMA

Detailed studies were conducted on three rice cultivars - IG10, an Ory za glaberrima Steudel; Moroberekan, a traditional Oryza sativa L.; and IDSA6, an improved O. sativa L. - in conditions with and without comp etition from weeds. IG10 suffered less from competition with weeds and suppressed weeds better than the O. sativa cultivars. IG10 accumulate d more biomass, produced more tillers, established a higher leaf area index, had higher specific leaf area and, in the earlier stages of gro wth, partitioned more of its biomass to leaves than the O. sativa cult ivars. Without competition from weeds, grain yields did not significan tly differ between the cultivars, but IG10 produced higher yields in c ompetition with weeds. The implications of these findings are discusse d in relation to the development of rice plants with good weed suppres sion characteristics.