Estimation of Heterosis and Inbreeding Depression in Sunflower (Helianthus annuus L.)

Four cytoplasmic male sterile lines were used as female parents for developing 44 hybrids involving eleven restorer lines. These hybrids along with their parents and F₂ progenies were raised to estimate heterosis and inbreeding depression in sunflower over two environments. The significant variance due to parents vs. hybrids indicated the presence of substantial amount of heterosis for days to maturity, plant height, achene yield per plant, 1000 seed weight and oil content. Significant negative heterosis over mid parent was observed for days to maturity while significant positive heterosis was observed for all other traits and was maximum for achene yield per plant ranging from 32.57 to 231.73 per cent. Most striking inbreeding depression was observed for achene yield per plant (upto 49.81 per cent) whereas very low magnitude of inbreeding depression was observed for days to maturity (upto 5.79 per cent). In general the characters which showed high heterotic effects had maximum inbreeding depression.