ESTIMATION OF SOME GENETIC PARAMETERS FOR YIELD AND ITS COMPONENTS IN UPLAND COTTON

Eight upland cotton varieties (Iranian, Bulgarian Grrd26, Lachata, French CA22, Syrian strain106, Pima, Bulgarian Chirpam 539 and Coker 310) were crossed in a half diallel mating system to assess the genetic of plant height, number of fruiting branches, number of bolls per plant, boll weight, earliness, ginning outturn and seed cotton yield per plant utilizing Mather and Jinks (1982) The results showed highly significant differences between genotypes for all the characters. Adequacy tests of additive dominance model revealed that data of all the characters were partially adequate for genetic interpretation except for ginning outturn. Additive component (D) was significant from zero for plant height, number of fruiting branches, ginning outturn and seed cotton yield per plant and was lower in magnitude than dominant components (H1 and H2) of variation for all traits. This was firmly supported by the value of (H1/D)0.5. Asymmetrical distribution of dominant and recessive genes in parents was found for number of fruiting branches, boll weight, ginning outturn and seed cotton yield per plant due to unequal estimates of dominant components (H1 and H2). This was confirmed by the value of H2/4H1. Graphical representation of Wr/Vr demonstrated that additive gene action plays a role in controlling the inheritance of plant height, number of bolls per plant, boll weight and seed cotton yield per plant, while the traits number of fruiting branches, earliness and ginning outturn was under the influence of over dominance. Low narrow sense heritability was exhibited by number of fruiting branches and boll weight, moderate for remaining traits, and its values ranged between 16.95% for number of fruiting branches and 53.18% for ginning outturn. This indicates that all the traits were under the control of dominant gene action, therefore breeding hybrids were useful for these traits.