Direct and indirect influence of yield components on yield in sunflower (Helianthus annuus L.)

Performance of sunflower varieties for yield and other characters, linear correlation between yield and its related characters and within yield components, regression analysis and path coefficient analysis to determine the direct and indirect influences of yield components on seed yield. The experiment was carried out in four replicated Randomized Complete Block Designs. It was observed that germination percentage, days to flowering, days to maturity, plant height, head diameter, number of achnes per head, seed index and seed yield per head varied significantly (P greater than or equal to 0.01) among varieties. It was found that HO-I recorded superior performance in seed germination (86.38%), days to flowering (68.78) days to maturity (106.48), plant height (210.38 cm), head diameter (15.38cm), number of achnes per head (1198.50), seed index (5.92, g) and seed yield (64.59, g/head) closely followed by Mehran-1. The phenotypic correlation with yield parameters indicated that days to flowering had positive and significant association with days to maturity (r= 0.468, plant height (r= 0.0282), head diameter (r= 0.488), and seed index (r= 0.472), while positive non significant with number of achnes per head (r= 0.197). However, days to maturity showed positive and significant correlation with plant height (r= 0.294), head diameter (r= 0.639), number of achnes per head (r= 0.362), while negative and significant with seed index (r= -0.496). While plant height showed positive and highly significant correlation with head diameter (r= 0.313), number of achnes per head (r= 0.416) and negative significant with seed index (r= -0.217). The association of head diameter was positive and highly significant with number of achnes per head (r= 0.616) and negative but highly significant with seed index (r= -0.799). The relationship of number of achnes per head with seed index was negative and highly significant (r= 0.399). It was furt her observed that the relation of days to flowering was positive and significant with seed yield (r= 0.312), similarly seed yield had positive and significant association with days to maturity (r= 0.243), plant height (r= 0.334), head diameter (r= 0.613), number of achnes per head (r= 0.842) and negative and highly significant with the seed index (r= -0.343). The positive direct effect on seed yield was observed incase of days to flowering (0.025), days to maturity (0.022), head diameter (0.310), number of achnes per head (0.170) and seed index (0.022), while plant height showed negative direct effect on seed yield (-0.050). It may be concluded that among the four varieties tested HO-1 and Mehran-II found to be high yielded, although took more days to maturity as compared to other two varieties evaluated. It was further concluded that among the yield components head diameter had the high positive direct effect on seed yield, followed by number of achnes per head are considere d as desirable yield components of sunflower.