Milling characteristics and grain quality traits of interspecific progenies of Asian rice (Oryza sativa) with African rice (Oryza glaberrima)

"Interspecific progenies of Asian rice (Oryza sativa) with African rice (Oryza glaberrima) were developed by the West Africa Rice Development Association (WARDA), and the identification of grain quality characteristics is urgently required to disseminate the progenies to West Africa. Milling characteristics and grain quality traits of the WAB450 series, which were developed from the cross of CG 14 (O. glaberrima) with WAB56-104 (O. sativa), were examined compared with those of O. glaberrima and several representative O. sativa varieties of West Africa. The 157 O. glaberrima lines, 179 interspecific progenies and 10 O. sativa reference varieties were grown in the 1997 rainy season in the WARDA irrigated ields by a standard method. Additionally, 47 lines of the progenies were grown in the 1998 rainy and 1999 dry seasons to examine the stability of grain quality characteristics to environmental changes. (1) The progenies were superior to O. glaberrima in terms of husking yield, milling yield and whiteness and translucency of milled rice. Such traits in most of the progenies were comparable to those of the O. sativa reference varieties. (2) A highly significant correlation was observed in the grain shape and size, whiteness and chalkiness in the progenies between the different cropping seasons, suggesting that those traits are varietal characters consistently observed under different growing conditions. A significant correlation was also obtained in milling characteristics, though the correlation coefficients were much lower than those of the grain quality traits. (3) The progenies with a high protein content were superior to those with a low protein content in terms of milling characteristics and translucency. The grains in the former were more slender than in the latter. (4) The existing progenies, developed through two backcrossings to the O. sativa parent, displayed various favorable milling characteristics and grain quality traits compared to the O. glaberrima parent. Therefore, it may be possibile to select promising lines from the existing progenies in these aspects."