Estimativas de parâmetros genéticos e estabilidade fenotípica em cultivadores de algodoeiro herbáceo

Abstract

Cotton is one of the most important crops worldwide because of its fiber is used as raw mat e- rial for the textile industry and the processing of fiber generates by-products of great commer- cial value. In Brazil, cotton is cultivated in several regions in different production systems, causing a high interaction genotypes x environments, which makes difficult to obtain adapted and stable materials. The objective of this work was to estimate the genetic parameters, sele c- tion index and phenotypic stability of upland cotton cultivars cultivated in the State of Mato Grosso. Sixteen genotypes were evaluated in eight environments of the State of Mato Grosso from the Regional Cotton Varieties Test from Cotton Breeding Program of Embrapa Cotton for the Savanna conditions in 2008/09 season. The evaluated characteristics were: seed cotton yield, fiber percentage, lint yield, fiber length, fiber strength and micronaire index. Individual and joint analyzes of variance were performed and the genetic parameters were estimated. The Mulamba & Mock selection index was applied and the adaptability and stability analysis was performed based on the GGE biplot multivariate methodology. Using the Mulamba & Mock index, the most productive and adapted genotypes were FM 993, FM 910, followed by CNPA MT 04-2080, BRS BURITI and CNPA MT 04-2088. In relation to the capture ratio of the GxA interaction in the first two axes by GGE biplot methodology it was observed 68.52% and 88.94%, for PROD and PRODF respectively. It was observed similarity in the behavior of the genotypes for the PROD and PRODF characteristics, the majority of the genotypes were stable in the set of environments, except for: BRS BURITI, DELTA OPAL and LD CV 02. As for the set of environments, it was observed that the Pedra Preta environment was the one that most contributed to the GxA interaction. There is genetic variability among the genotypes for the agronomic and fiber quality characteristics, and can be used for crosses in other cotton breeding programs, aiming at the incorporation of specific characteristics. The GGE biplot methodology proved to be very efficient to select stable and adapted genotypes in the cotton crop.