Genetics of fibre quality traits in cotton (Gossypium hirsutum L.)

Five upland cotton varieties were crossed in a complete diallel mating system to assess the genetics of fibre length (FL), fibre strength (FS), fibre fineness (FF), fibre uniformity (FU) and fibre elongation (FE) utilizing Mather and Jinks approach. Differences were found to be significant (P<0.01) for all the characters. Adequacy tests revealed that data of all the characters were partially adequate for genetic interpretation except FE. Additive component (D) was significant in all the traits and was lower in magnitude than dominant components (H1 and H2) of variation for FS and FU which was firmly supported by the value of H1/D(0.5). Dominant genes were in excess than recessive genes in the parents for all the traits except for FF. Asymmetrical distribution of dominant and recessive genes in parents for all characters was confirmed, and soundly sustained by the value of H(2)/4H(1). The h(2) value was insignificant for all the characters except FS. Moderately high narrow sense heritability (h(n.s)(2)) was exhibited by FF, FU and FE, while SL and FS possessed low heritability. Graphical representation demonstrated additive gene action for SL, FF, and FE whereas; FS and FU were controlled by overdominance effects. Full sib or half sib family selection, pedigree and progeny test would probably be necessary to achieve the genetic progress for SL, FF, and FE while hetrosis breeding could be fruitful for improvement of FS and FU.