Abstract: Six upland cotton (G. hirsutum L.) varieties were crossed in all possible combinations.
The parents and F1 were sown in a replicated experiment. Haymans
diallel cross analysis was employed to investigate the nature of gene action
involved in the inheritance of number of sympodial branches per plant, number
of bolls per plant, boll weight, yield, ginning out turn %, staple length, fiber
fineness and fiber strength. The diallel analysis revealed that all the characters
were polygenically inherited and exhibited partial dominance with additive gene
action. The estimation of component of variation for these characters suggested
that the (D) additive component was significant in all the traits under study
and was lower than dominant components (H1 and H2) of
variation except for number of sympodial branches per plant, number of bolls
per plant and seed cotton yield per plant, where the dominant components were
higher in magnitude than additive. The positive estimate of F indicated that
dominant genes were in excess than recessive genes in the parents for all the
traits except for ginning out turn percentage and fiber fineness. The ratio
of H2/4H1 indicated largely asymmetry of positive and
negative genes in parents for number of bolls per plant, seed cotton yield,
staple length, fiber fineness and fiber strength, and symmetrical distribution
of positive and negative genes in the parents was observed for number of sympodial
branches per plant, boll weight and ginning out turn percentage. The h2
value for number of number of sympodial branches per plant, number of bolls
per plant, boll weight, seed cotton yield per plant, ginning out turn, staple
length, fiber fineness, and fiber strength was positive and significant which
indicated that hetrotic breeding was rewarding for these traits. The correlation
between Wr + Vr and Yi indicated that dominant
genes are mainly responsible for the expression of all traits. Mass selection
will be an effective method for improving the boll weight and reciprocal recurrent
selection method will be helpful for improving the sympodial branches per plant,
number of bolls per plant, seed cotton yield, fiber fineness and fiber strength.
The full sib or half sib family selection, pedigree and progeny test would probably
be necessary to achieve the genetic progress for GOT% and staple length. |