Information about heritability and combining ability for neps and seed coat neps is necessary for the cotton breeding strategies. Seven cotton cultivars including 4 lines and 3 testers were mated in line x tester mating design. The 19 genotypes were grown in RCBD with three replications in Aydın-Turkey conditions during 2014 growing season. Non-additive gene action was important in the expression of seed coat nep size, nep count and nep size. The parental lines Carmen and Claudia were good combiners for most neppiness characteristics. Carmen x Flash, Julia x ST-468, Claudia x Carisma and Gloria x Flash were the superior crosses for selection in further generations of neppiness breeding. It was recommended that the selection of individual plants for neppiness should be performed in later generations (F4-F6).

Genetic evaluation of segregating populations is one of the primary activities of cotton breeders. Seven cotton genotypes were crossed in a line ? tester mating design. The population of 12 F1, 12 F2 and their parents were tested in Randomized Complete Block Design with three replications at the Nazilli Cotton Research Institute of T?rkiye during the 2014/2015 cotton-growing season. The genetic variability was significant for all characters studied. ?2GCA/?2SCA indicated non-additive gene action in controlling seed cotton yield (F2), ginning out-turn (F1) and fiber quality traits for both generations. The highly favourable GCA effects for seed cotton yield and fiber strength were recorded in the Carmen cultivar. Carmen ? Carisma hybrid exhibited high mean performance and SCA effects for seed cotton yield and fiber strength, while the performance of Gloria ? ST-468 was superior in terms of ginning out-turn. We concluded that individual plants with desired traits should be selected in later generations due to the preponderance of non-additive gene actions.

The experiment was laid out to estimate heritability, genetic correlation and genetic advance for seed cotton yield, yield components and fiber quality in F 1 populations by line x tester mating design. Seed index (0.789), ginning outturn (0.758), boll weight (0.644), days to first boll opening (0.635) and boll number (0.617) exhibited a high degree of broad-sense heritability. The significant and positive genotypic correlations with seed cotton yield recorded in boll number, boll weight, fiber strength, sympodial branch number, days to first flower and seed index. The correlated response was magnitude for boll number, boll weight and sympodial branch number. The boll number and sympodial branch number represented high heritability coupled with genetic advance. The indirect selection of the boll weight and the sympodial branch was more efficient for high yielding cotton breeding.

The aim of this research was to evaluate the efficiency of the recurrent selection method for increasing ginning out-turn, optimizing fiber characters and neppiness in cotton breeding. This study started with the creation of 24 F1 combinations at Nazilli Cotton Research Institute in 2013. According to recurrent selection method, plants of 45 populations were evaluated for the first cycle of the recurrent selection procedure such that the F1: C1S0 was evaluated in 2017, the F2: C1S1 in 2018 and the F3: C1S2 in 2019. The fiber nep number and size decreased with each filial generation (from F1 to F3). Generally, high heritability coupled with genetic advance was estimated for ginning out-turn, fiber characters and neppiness. The results of inbreeding depression values indicated that ginning out-turn and fiber length in the population increased while the fibers became coarser under stable fiber strength. In addition, inbreeding depression for nep and SCN (Seed Coat Neps) number were higher than that of nep and SCN size. Our results showed that the recurrent selection method can be successfully applied in a cotton breeding program.