Caracterização de cultivares de algodão tolerantes ao estresse hídrico baseada em variáveis de crescimento e na atividade das enzimas antioxidativas

Abstract

Because of climate change is increasingly frequent on the planet, agriculture is suffering various impacts due to dependence on environmental factors. The drought has been one of the abiotic factors that have most contributed to reduction in crops production. The cotton (Gossypium hirsutum L.) is one of the most cultivated species worldwide, exerting an important socio-economic role, particularly for the use of fiber in the textile industry. In order to identify materials with the ability to tolerate water stress conditions, this study evaluated cotton cultivars based on growth and biochemistry variables. At 45 days after emergence, nine cotton genotypes (FMT 705, FM 966, BRS Rubi, BRS 286, FMT 701, CNPA ITA 90, CNPA 5M, CNPA 7MH, BRS Seridó), herbaceous and arboreal sizes, underwent water stress for a period of seven days in a greenhouse at Embrapa-Algodão. The cultivation was performed in 5 liter pots containing sandy soil previously fertilized according to the recommendations of the culture. The experimental design was completely randomized, with bi-factorial 9 x 2 (9 genotypes x 2 water treatment), with four replications. The analyzed growth variables were plant height, stem diameter, number of leaves, length and weight of the roots. The assessed biochemical variables were the antioxidative activity of enzymes: SOD, CAT and APX, estimated by spectrophotometry. The cultivars were classified adopting multivariate methods, through the canonical variables and cluster analysis via UPGMA. It was observed that the stress imposed affected all genotypes, although shown different responses. However, the most suitable materials have the ability to grow even in the face of drought that have been submitted and also included best performance of antioxidant enzymes to prevent cellular damage. Under these conditions, the most adapted genotypes were BRS 286, CNPA 7MH and CNPA 5M, considered as the best candidates for hybridizations aiming tolerance to semiarid environments.