Produção de algodoeiros naturalmente coloridos sob estresse salino no segundo ciclo de cultivo após poda.

Abstract

The cultivation of cotton stands out as an important socio-economic activity in the Brazilian agricultural scenario. In northeastern Brazil, however, production is limited by low rainfall and the presence of salt ions in various water sources used for irrigation. It is necessary to identify genotypes that tolerate salt stress in order to provide support to its cultivation in such conditions. In addition, in order to reduce the cycle of plants, with advantages over production costs, it is possible to perform pruning after harvest cotton, it is important to study the use of this practice under saline limitations. In this sense, the objective was to evaluate the salt tolerance of cotton genotypes naturally colored during the second cycle of crop production, after pruning. The experiment was conducted in a greenhouse, evaluating three genotypes of cotton (G1 – BRS Rubi ; G2 – BRS Topázio e G3 – BRS Safira), submitted to two levels of electrical conductivity of water (ECw = 0.8 dS m-1 and 8.0 dS m-1) distributed in a randomized block design. The combination of factors resulted in 6 treatments (3 x 2), with five replications and five plants per plot. The distinction of treatments, varying the level of ECw, began 30 days after pruning (DAP), extending to the end of the cycle, evaluating aspects of growth and physiology, in three of the plant development stages (growth and intense flowering – 60 DAP; beginning of fruit– 75 DAP and formation of full production – 90 DAP), in addition to biomass and production of variable components. Data were subjected to analysis of variance by 'F' test and when significant were compared by Tukey test (p <0.05). Salinity affects negatively growth variables and physiological parameters, especially gas exchange, in addition to biomass production and yield components. The three cotton genotypes are classified as moderately tolerant to salt level of 8.0 dS m-1 in the second cycle after pruning.