Eco-physiological characteristics of interspecific progenies between African (Oryza glabberima Steud) and Asian (Oryza sativa L.) rice

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The purpose of this research is to characterize African (Oryza glaberrima) and Asian (0. saliva) rice parents with their interspecific progenies developed in West Africa Rice Development Association (WARDA) in terms of dry matter production, grain yield and weed competitiveness.1) The African rice parent showed extremely high leaf area that aided superior vegetative growth compared with Asian rice, and the progenies showed the intermediate values. The CO2 exchange rate (CER), however, was lower in African rice compared with Asian rice. The progenies showed more erect leaves compared with African rice which has droopy leaves.2) Fast development of leaf area in African rice led to fast ground cover, so that African rice produced two times greater dry matter under low weeding level, and 1.3 times higher grain yield than Asian rice. African rice showed the lowest yield reduction due to no weeding by 30%against 50% in Asian rice.3) African rice produced significantly greater root dry weight than Asian rice. The progenies produced the intermediate amount. On whole plant dry matter basis water use efficiency (WUE) was higher in African rice than Asian rice and the progenies. It was concluded that during moderate level of water stress greater water extraction capacity in African rice gave more importance for the maintenance of better crop growth4) Average leaf area and dry matter production of African rice cultivars was found to be higher than the Indica and Japonica type cultivars due to the inoculation of mix-cultured rhizobacteria. The results have shown that African rice cultivars could produce better interaction with the free-living rhizobacteria.