Abstract
Heterosis, potence ratio and combining ability for seven qnantitative traits were examined in F, generation of inte"mrietal cro"es of four wheat genotypes using randomized bloek design. Results demonstrated that the parents and their F, hybrids differed signifieantly (P> 0.05) for four out of seven traits stndied, indicating substantial variation within parents and their hybrids. Manifestation of heterosis was observed for all the traits in at least one or more crosses. The highest MP heterosis (31.12%), heterobeltiosis (23.31%) and potence ratio (4.911 were displayed by the hybrid Koh-i-noor-83 x Mehran-89 for tillers per plant followed by yield per plant. Heterotic effects were appreciably influenced by the hybrid genotype, the direction of cross and the trait concerned. General combining ability analysis indicated that the large portion of total genetic variation for four out of seven traits was associated with genes which were additive in their effect. Specific combining ahility was non-significant for all the traits indicating absence of epistasis and dominant gene effects. Paeent Jauhar- 78 was the best general combiner having positivc GCA effects for six out of seven traits. C,oss Koh-i-no oe - 83 x Mehran-89 was the best cross combination followed by Yecora x Jauha,-78 since these crosses exhibited high parent hete,osis in at least five out of seven traits. GCA effects were more pronounced than SCA effects for all the traits except grains per spike. Therefore, selection has been advocated on the basis of GCA's of the parents which can be exploited through conventional breeding programme. Key words: bread wheat, combining ability, heterosis, potence ratio
