Abstract The aim of this study was to estimate the general combining ability of the parents and specific combining ability of hybrids considered for the development of high yielding and better quality cultivars. Seventeen genotypes and 52 F 1 hybrids obtained by crossing 4 lines and 13 testers in line · tester mating system during 2003 were sown in randomized complete block design in 2004. Line · Tester analysis revealed significant GCA and SCA effects for all the traits except fibre elongation. Preponderance of non-additive gene action was obtained for seed cotton yield per plant and majority of its component traits including fibre traits. Among the parents: PIL-8 for days to 50% flowering, CCH-526612 for boll weight, CITH-77 for number of open bolls per plant and CNH-36 for seed cotton yield per plant were detected with higher general combining ability. Parent, CCH-526612 for 2.5% span length, fibre strength and fibre elongation and AKH-9618 for micronaire value, fibre strength and fibre elongation were good combiners for fibre quality traits. The F 1 s achieved high seed cotton yield by producing more number of open bolls. The high yielding hybrids with acceptable fibre quality traits were: CISV-24 · LH-1995, H-1242 · PIL-8 and RS-2283 · SGNR-2 de- ducted with significant SCA effects for seed cot- ton yield and fibre characteristics; 2.5% span length and fibre strength. These cross combina- tions involved at least one parent with high or average GCA effect for a particular trait. Keywords Cotton Æ General and specific combining ability Æ Fibre quality Æ Line · tester analysis Introduction Development of a new variety with high yield and fibre quality parameters is the prime objective of all cotton breeders. The first step in a successful breeding program is to select appropriate parents. Line · tester analysis provides a systematic ap- proach for detection of appropriate parents and crosses superior in terms of investigated traits. Combining ability describes the breeding value of parental lines to produce hybrids. Sprague and Tatum (1942) used the terms general combining ability (GCA) to designate the average perfor- mance of a line in hybrid combinations and specific combining ability (SCA) as deviation in performance of a cross combination from that predicted on the basis of the general combining abilities of the parents involved in the cross. In order to choose appropriate parents and crosses, S. L. Ahuja (&) Æ L. S. Dhayal Central Institute for Cotton Research, Regional Station-Sirsa, Haryana 125 055, India e-mail: slahuja2002@yahoo.com Euphytica (2007) 153:87–98 DOI 10.1007/s10681-006-9244-y 123 Combining ability estimates for yield and fibre quality traits in 4 · 13 line · tester crosses of Gossypium hirsutum S. L. Ahuja Æ L. S. Dhayal Received: 28 March 2006 / Accepted: 14 July 2006 / Published online: 30 August 2006 Ó Springer Science+Business Media B.V. 2006