Estresse salino cumulativo em genótipos de algodoeiro colorido no ciclo de produção após a poda.

Abstract

Because it is one of the agricultural activities of great socioeconomic importance for Brazil, the cultivation of the herbaceous cotton (Gossypium hirsutum L. latifolium Hutch) in the several areas of the arid and semi-arid regions of the Brazilian Northeast, has been suffering from the scarcity of water Sweet to the water demand of the plants, being available waters with high content of salts, limiting the growth and the production of the cultures. The objective of this work was to evaluate the growth, physiology and production of two genotypes of colored cotton, during different stages of development of the plant after pruning, under conditions of low and high salinity. The experiment was carried out in a protected environment (greenhouse) of the Technology and Natural Resources Center of the Federal University of Campina Grande located in the municipality of the same name, Paraíba. The treatments consisted of two cotton genotypes (BRS Rubi and BRS Safira) submitted to ten salinity management strategies, varying the water quality applied in different phases of the plant cycle, using public water diluted with rainwater and NaCl, CaCl2.2H2O and MgCl2.6H2O salts in the proportion 7: 2: 1, diluted in the water supply. The experimental design was in randomized blocks, resulting in 20 treatments (2 x 10) with three replications and three plants per plot in pots containing one plant per pot. Growth and plant production variables were evaluated at 31, 55 and 102 days after pruning. The data were submitted to the Fischer test, comparing the means by Scott-Knott (p <0.05) for the irrigation management strategies and Tukey's test, (p <0.05) for the cotton genotypes. Among the genotypes, the 'BRS Sapphire' was the most tolerant to salinity, with better mechanisms of adaptation to saline stress, regardless of the stage of development. The successive application of saline water in the vegetation, flowering and fruiting was detrimental to growth and development and there was no recovery of the plants after suspension of stress. Cotton plume production is more affected by salinity when applied in both the flowering phase and the formation of the cocoons.