Análise genética para caracteres agronômicos e tecnológicos de fibra em genótipos de algodoeiro herbáceo (Gossypium hirsutum L. var. Latifolium Hutch.)

Abstract

This work aimed to estimate the general combining ability (GCA) and the specific combining ability (SCA) for agronomic traits among six upland cotton genotypes and their fifteen hybrid combinations; and to determine the predominant genetic effects in the control of the evaluated traits. In 2015, six cotton genotypes: FM 993, CNPA 04-2080, PSC 355, TAM B 139-17, IAC 26 and TAMCOT – CAMD-E, and fifteen hybrid combinations were evaluated at the Experimental Station of Embrapa Algodão, located in Patos - PB. The experiment consisted of a randomized block design with three replications. The following characteristics were evaluated: plant height (PH, cm); appearance of the first flower (AFF, days); appearance of the first boll (AFB, days); weight of one boll (BW, g); cotton seed yield (CSY, kg/ha); lint percentage (LP, %); cotton fiber yield (LY, kg/ha); length (LEN, mm); uniformity (UNI, %); strength (STR, gf/tex), and fineness (FIN, IM). Diallel analysis was carried out according to the method 2, model 1 of Griffing (1956). Significant differences were detected between the treatments and between the combining abilities estimates (GCA and SCA). Additive effects were predominant for the following characteristics: PH, AFF, AFB, LP, LEN, UNI, STR, FIN and non-additive effects were predominant for: BW, CSY and LY. The genotypes CNPA 04- 2080, IAC 26 and FM 993 showed highest estimates of gi for yield, and the genotype TAM B 139-17 presented the highest estimates for fiber characteristics. In general, the best combinations were: FM 993 x PSC 355, FM 993 x TAMCOT-CAMD-E, CNPA 04-2080 x TAM B 139-17, CNPA 04-2080 x TAMCOT-CAMD-E, PSC 355 x IAC 26 and TAM B 139- 17 x IAC 26, since they have the largest SCA (sij) with at least one of the parents of high GCA (gi). Therefore, they are indicated for extraction of elite lines and for the obtainment of superior genotypes.