Capacidade de combinação entre genótipos de algodoeiro herbáceo no semiárido nordestino

Abstract

Cotton is the main source of natural fiber for the textile industry, where Brazil stands out as one of the largest producers and exporters worldwide. In the Brazilian semi-arid region, this crop is of great economic importance, even if grown in rainfed. Cotton breeding programs in Brazil have sought to improve productivity, yield in ginning, fine, resistant and uniform fibers. This work aimed to estimate the general and specific capacity of combinations between cotton genotypes, select the best parents and hybrid combinations with higher productivity and quality in semiarid conditions. The experiment was conducted at the Embrapa Algodão experimental station, in the city of Barbalha, CE. The treatments were composed of 24 F3 families, with four replications, and two more treatments that served as controls (cultivars BRS 286 and BRS 416). The experimental design was in randomized blocks. The following agronomic characteristics were analyzed after harvest: cotton seed and feather productivity (kg ha-1), fiber percentage (%) and boll weight (g), and the characteristics of the fiber: length (mm), strength (gf tex-1), elongation, fineness and reliability index. The fiber analyzes were performed with the aid of the HVI equipment (Uster HVI 1000), from the Embrapa Cotton fiber laboratory. The results show that all the agronomic characteristics evaluated showed significant differences at 1%, showing the genetic variability between the F3 hybrids. The general and specific combinatory capacity estimates showed a significant effect for all characteristics, inferring a predominance of additive gene action in the control of most of the evaluated characters. Additive gene effects are superior to non-additive effects for all characters, except for micronaire index and reliability index. Therefore, the best parents are CNPA 2009 152, CNPA BA 2009 2247, BRS 293 and BRS AROEIRA. The most promising hybrid combinations for improving fiber agronomic and technological characteristics are: CNPA BA 2009 2247 x BRS 293; CNPA BA 2009 2247 x BRS 286; BRS 336 x BRS 286 and CNPA BA 2010 1366 x GUAZUNCHO.