Genetic analysis of earliness indicators in upland cotton

Genetic bases of earliness in upland cotton were investigated by recording and analyzing data on different phenological and morphological traits related to earliness. All traits inclusive of days to squaring, days to flowering, vertical flowering interval, horizontal flowering interval, days to first boll opening, boll maturityperiod, node number for the first fruiting branch and height for first fruiting showed significant variation. Additive components D was significant for all the traits studied and more than the values of dominance components H1 and H2 thus confirming the presence of additive gene action. Estimates of narrow sense heritability were low for days to squaring, moderate in the boll maturity period and high for all other traits. Degree of dominance was less than unity hence partial dominance is found in almost all the traits. The predominance of additive genetic effects along with reasonable estimates of heritability suggested early generation selection and pedigree method of selection may be followed for almost all the traits.