IDENTIFICATION OF FAVORABLE EXOTIC AND ELITE ALLELES FOR FIBER QUALITY AND YIELD IMPROVEMENT IN UPLAND COTTON USING MULTIPLE ASSOCIATION MODELS

This thesis highlights the importance of exotic Upland cotton germplasm or the primitive accessions sampling most of the botanical races. Most of the QTL regions for fiber quality traits were devoid of favorable alleles originating from this gene pool, except some regions where multiple exotic lines improved upon the DES56 allele, indicating alleles that might have been left behind during the long history of genetic improvements in elite Upland cotton gene pool. Three lines- T1046, T063, and T326 showed higher potential for their inclusion in breeding programs targeting fiber quality. However, fiber yield traits indicated a high frequency of dominant QTLs possessing negative effects, along with the additive QTLs discouraging introgression from these exotic lines for fiber yield traits. Hence, to mitigate the linkage drag from these undesirable regions and the negative dominance effects, selection practices should be performed in later generations along with the implementation of genomic selection techniques.