Heterosis and inbreeding studies for agronomic and quality traits in rice (Oryza sativa L.)

Heterosis and inbreeding depression was studied for twenty characters in seven parental lines and their eleven hybrids in rice. Significant positive average heterosis and heterobeltiosis was observed for effective tillers, grain yield /plant, panicle density ,filled grains /panicle, panicle length, length/breadth ratio, head rice recovery, milling percent and hulling percent. Significant negative heterosis was observed for days to 50 % flowering in desired direction.  Among the crosses, Kavya × WGL-915, BPT-5024 × WGL-915, Kavya × HKR-08-62, BPT-5204 × MTU-1075 and BPT-5204 × Gontrabidhan recorded significant positive heterobeltiosis for grain yield/plant and also two to three important economic characters and showed significant positive inbreeding depression . The inheritance of yield, yield components and quality traits were mostly governed by non additive type of gene action as evident from high heterosis followed by high inbreeding depression and in such cases heterosis breeding is more feasible to achieve quantum jump in rice yield while, pedigree method in few specific crosses showing low inbreeding depression in order to improve characters like head rice recovery, kernel length, length/breadth ratio, kernel length after cooking and days to 50% flowering etc. Selection of good parents was found to be most important for developing high yielding  rice varieties with desirable characters.