Nature and magnitude of heterosis and inbreeding depression for grain yield and yield attributing traits in nutritional rich rice (Oryza sativa L.) Crosses

Abstract

Studies on heterosis for days to 50% flowering revealed that highest magnitudes in negative direction were expressed by WGL-32100 x Ramappa, Ramappa x NH-787, RP-Bio-5478-270 x NH-787, RP-Bio-5478-166 x DRR Dhan-40 and RP-Bio-5478-176 x DRR Dhan-40, but due to a substantial increase in F2 generation, not recommended for direct selection. The crosses MTU 1010 x Ramappa, WGL-32100 x RP-Bio-5478-185, WGL-32100 x NH-686, WGL-32100 x NH-787, Ramappa x NH-686 and Ramappa x NH-787 were recommended for selection due to high heterosis followed by low inbreeding depression for improving productive tillers per plant. Among the characters studied, 1000 grain weight registered maximum level of heterosis with highest in WGL-32100 x Ramappa, WGL-32100 x RP-Bio-5478-270, WGL-32100 x RP-Bio-5478-185, Ramappa x RP-Bio-5478-270 and WGL-32100 x RP-Bio-5478-166. It is interesting to note that, high heterosis was followed by low inbreeding depression in majority of the crosses, which indicated the presence of additive gene effects in the inheritance of this character. Therefore, for improvement of grain yield, an indirect selection for plants having higher test weight would be more advantageous. In most of the cases, the cross combination which showed high heterosis for grain yield exhibited better mean performance and also corresponding heterosis for 1000 grain weight too, which made a clear way for selection of the plants having higher test weight for ultimate improvement of grain yield per plant.