Genetic analysis of agronomic and fibre traits using four interspecific chromosome substitution lines in cotton

Backcrossed chromosome substitution lines (CS-B) have been developed with a homologous pair of chromosomes or chromosome arms of Gossypium barbadense (3-79) germplasm substituted for the homologous Gossypium hirsutum (TM-1) chromosomes or chromosome segments. We report on agronomic and fibre trait performance of four backcrossed chromosome or chromosome arm substitution lines including chromosomes 01, 11sh (chromosome 11 short arm), 12 sh and 26 Lo (chromosome 26 long arm). Data for agronomic and fibre traits were collected from replicated field experiments at two different locations in 2 years, and analysed under an additive dominance genetic model. CS-B 12sh had higher, while CS-B 01 and CS-B 26Lo had lower boll weight than TM-1. The presence of significant negative additive effects for micronaire with CS-B 01 and significant positive additive effects for elongation and fibre strength with CS-B 11sh suggested the substituted chromosome arms of 3-79 in these CS-B lines were more likely carrying genes causing these effects. Results revealed that several CS-B lines had significant homozygous and heterozygous dominance effects for different agronomic and fibre traits suggesting that specific CS-B lines may be useful for improving agronomic and fibre traits in hybrid cottons. These CS-B lines also provide novel genetic resources for improving upland cotton germplasm.