Análise genética para caracteres de fibras em genótipos de algodoeiro submetidos a estresse hídrico

Abstract

The success of a breeding program depends, in general, of genetic resources to be used to generate variability and subsequently selecting the best hybrid combinations that can produce promising segregating. Therefore, estimates of general (GCA) and specific combining (SCA), and also the heterotic expression between junctions are widely adopted tools and contribution to assist in the development of new cultivars. This study aimed to estimate genetic parameters through the general (GCA) and specific combining (SCA) of technological characteristics of cotton fiber using partial diallel mating scheme between herbaceous and arboreal cotton under two water regimes. The research was conducted at Embrapa experimental station in Barbalha, Ceará, using the experimental design of randomized blocks, with joint analysis comprised 20 (hybrids) and 2 (water system) with three replications. Technological fiber characteristics were evaluated in Fiber and Yarn Cotton Embrapa Technology Laboratory in Campina Grande-PB, through the HVI (Uster HVI 1000) by taking 20 bolls / plot as standard sample. The traits Evaluated Were: fiber length UHM (mm), fiber uniformity UNF (%), short fiber index SFI (%), strength (STR gf / tex), elongation ELG (%), micronaire index MIC, maturity MAT, reflectance Rd (%) and count strength product (CSP). It was found that the water systems under study influence on the technological characteristics of the fiber. additive effects and no additives were found, the first more significant for presenting mean squares of the highest GCA than the CEC, for most characters. In general, the FM 966 genotypes (UHM, UNF, STR, SFI and CSP), FMT 705 (MIC), BRS Rubi (ELG and Rd), CNPA 5M (UHM, UNF, SFI, STR, ELG and CSP) and BRS Seridó (MIC and MAT) were contributing to improve the technological characteristics of the fiber under water stress condition. The best hybrid combinations, based on the CEC were FMT 701 x CNPA ITA 90 for (UHM, UNF, SFI and CSP), FM 966 x CNPA 5M (UHM, Rd and CSP), FM 966 x BRS Seridó (UNF and SFI) BRS 286 x BRS Seridó (STR, ELG and CSP), and combinations FMT 705 x CNPA ITA 90 and BRS Rubi x CNPA ITA 90 (MIC).