Comparative yield component analysis in Gossypium hirsutum parents using fibre quality grouping

The usual practice of estimating association and direct and indirect effects among various traits in Gossypium hirsutum is with ungrouped genetic material based on staple length and strength. During 2003-2004 and 2004-2005 genotypic and phenotypic association among ten characters were estimated in G. hirsutum genotypes: (i) set-1: 10 genotypes of low fibre strength (<=196.2 mN/tex) and medium staple length (<=25.0 mm), (ii) set-2: 10 genotypes of high fibre strength (>=235.44 mN/tex) and long staple length (>=28 mm) and (iii) set-3: 20 genotypes of set-1 and 2. The differences in the estimates of associations, direct and indirect effects for different characters in fibre quality groups were examined. The complete analysis of variance for the characters under study viz; days to 50% flowering, plant height (cm), number of monopodial and sympodial branches per plant, seed cotton yield per plant (g), boll weight (g), total number of bolls per plant, lint %, 2.5% span length (mm) and fibre strength (mN/tex) indicated highly significant genotypic differences for genotypes, years and genotype x years interaction. Variation within medium staple length and low strength (set-1), high staple length and high strength genotypes (set-2) and their interaction with year were also significant. Medium staple length and low strength (set-1) versus high staple length and high strength component (set-2) was significant for all the traits indicating significant variability between the sets. A true relationship and direct selection were observed for days to 50% flowering, number of monopodial and sympodial branches per plant with seed cotton yield in the three sets suggesting that separation of genetic material based on staple length and fibre strength for improvement of seed cotton yield through these traits is not required. Magnitude and direction of direct effect and association with yield of the other traits; plant height, number of total bolls per plant, boll weight, lint %, staple length and fibre strength differed between the sets. This study concluded that more successful planning of a breeding programme can be made through path coefficient analysis if the genetic material is grouped based on staple length and fibre strength.