Prospescção de genótipos de algodoeiro tolerantes ao estresse hídrico baseada em caracteres agronômicos e fisiológicos

Abstract

Cotton is the most important natural fiber culture in the world. In Brazil, crop is usually conducted in places with low water availability. Although it has a large genetic plasticity to adapt to these environments, this species can undergo physiological variations due to lack of water, negatively impacting the productivity and fiber quality, making it necessary to adopt summer tolerant genotypes to avoid crop frustration. In this sense, this work was carried out to identify productive and drought-tolerant cultivars for later use in hybridization works. We evaluated nine cotton genotypes (seven upland and two shrubs) and two water treatments (control and stress) in a completely randomized design with a 9 x 2 factorial scheme, with four replications. Water stress consisted of the total suspension of the irrigation for 21 days from the emission of the first floral bud. Plants were grown in pots of 45 L, containing previously fertilized sandy soil. We evaluated physiological, growth, production and fiber characteristics on cultivars. Data were submitted to univariate and multivariate analyzes (Canonical Variables). We verified that BRS Rubi, BRS 286, BRS Seridó, CNPA 5M and CNPA 7MH were the most tolerant ones to the imposed water stress and responded differently to the mechanisms of resistance to drought. Under water stress conditions, genotypes that produced fibers with better characteristics were CNPA 7MH, CNPA 5M, BRS 286 and BRS Serido, with highlight to the CNPA 7MH.