INTERSPECIFIC ORYZA-SATIVA L X ORYZA-GLABERRIMA STEUD PROGENIES IN UPLAND RICE IMPROVEMENT

Fertile interspecific progenies between Oryza sativa L. and O. glaberr ima Steud. were produced through backcrossing and doubled haploid bree ding (DHB). Backcrossing with the O. sativa parents increased fertilit y and helped combine the O. sativa and O. glaberrima features. The use of DHB to generate a large proportion of doubled haploids from inters pecific F-2 hybrids, helped overcome constraints associated with the c onventional breeding of these species, such as: (1) slow fixation of t he lines, (2) frequent partial sterility of the progenies and (3) low recovery of useful recombinants. Although true interspecific progenies between O. sativa and O. glaberrima were generally rare, their occurr ence in some populations was as high as 30%. Some progenies combined t he high yield potential of O. sativa, a result of high spikelet number caused by secondary branches on the panicle, with useful traits of O. glaberrima such as rapid leaf canopy establishment and high N respons iveness. The progenies partly inherited the O. glaberrima parents' hig h specific leaf area (SLA) during early growth, theoretically improvin g competitiveness with weeds, and from the O. sativa parents the rapid decrease in SLA towards the reproductive stage, theoretically allowin g for high leaf photosynthetic rates and high grain yield. Research is in progress to develop new interspecific plant type concepts for reso urce poor, weed prone upland rice environments in West Africa.