Abstract:

In this study 23 genotypes, including 8 cultivars and 15 advanced lines were consecutively grown under 2 temperature regimes in 2004 and 2005 at the Post Graduate Agriculture Research Station, University of Agriculture, Faisalabad, Pakistan. Lint yield and its component traits, i.e. lint weight per boll, lint weight per seed, fiber length, fibers per seed, fibers per unit surface area, lint weight per unit surface area, and fiber weight per unit surface area, were measured and analyzed for heritability, genetic advance, and correlations. Phenotypic correlations were also partitioned into path coefficients, keeping lint yield as the resultant variable and other components as causals. The heat-stress regime showed higher estimates of broad sense heritability, genetic variability, and genetic advance for all basic lint yield traits, except for fiber weight per unit length. Similarly, response to the selection was high under the heat-stress regime. The basic lint yield component showed a stronger relationship to lint yield (R2 = 0.77) under the heat-stress regime, indicating some value of these traits under heat stress. Both path analysis and multiple regressions revealed that fibers per seed had the greatest direct effect on the lint yield under both regimes.

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