Özet:

Improvement in fibre length is important for the textile industry in utilising high speed yarn spinning technology and in expanding the array of yarn products. High tensile strength fibre is needed for good spinning, especially with fast modern spinning machines. The usual practice of estimating correlation coefficients and the direct and indirect effects of component traits of seed cotton yield is without grouping the genetic material on the basis of fibre length and strength. Hence, the present investigation was carried out on these aspects by grouping the 20 F1 hybrids into 3 sets on the basis of fibre length and strength, viz, (i) 10 hybrids of low fibre strength (£20 g tex-1) and medium staple length (£25.0 mm), (ii) 10 hybrids of high fibre strength (>=24 g tex-1) and longer fibre length (>=28 mm), and (iv) 20 hybrids, i.e. all the 10 hybrids of set 1 and set 2 of Gossypium hirsutum L. cotton for agronomic and fibre quality traits. Significant genotypic difference existed among the hybrids in all the sets for all the characters studied. The direction of association coefficient of the traits and direct effects on seed cotton yield differed for all the traits except for the number of bolls per plant, boll weight and fibre strength in set 1 and set 2. Set 1 gave the same direction of association with seed cotton yield as obtained in set 3 of usual practice except for the traits ginning out turn (GOT) and days to flowering, whereas set 2 gave similar information to the usual practice for the traits days to flowering, total bolls, boll weight and GOT, and differed for other traits. The present study, therefore, indicates that the hybrid population needs to be grouped on the basis of fibre length and fibre strength prior to estimation of correlation coefficients and direct and indirect effects of other traits on seed cotton yield.

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