Estratégias de manejo com uso de biocarvão e bioestimulante na mitigação dos efeitos danosos da salinidade no crescimento e fisiologia de plantas de algodão herbáceo

Abstract

Cotton is a crop of great commercial importance due to its fiber, which is widely used by the textile industry, as well as for its various by-products. Considering that it is cultivated in several countries and under distinct climatic conditions, cotton shows fluctuations in productivity, with salinity being one of the main limiting factors. To mitigate the harmful effects caused by salts, the adoption of ameliorating strategies has become increasingly necessary. Coconut shell-based biochar and the use of biostimulants have emerged as alternatives for mitigation due to their distinct mechanisms of application and action. Therefore, the objective of the present study was to evaluate how the adoption of different strategies can mitigate the effects of salt stress on cotton. The experiment was conducted in a greenhouse at the Federal University of Ceará, Department of Crop Science, in a completely randomized design (CRD), arranged in a 4 × 2 factorial scheme, in which the first factor corresponded to the mitigation strategies (control, biochar, biostimulant, and biochar + biostimulant), and the second factor corresponded to the electrical conductivity of the irrigation water (0.2 dS m⁻¹ and 4.5 dS m⁻¹). Morphophysiological, biochemical, parameters were evaluated. The results showed foliar accumulation of Na⁺ and higher electrolyte leakage in salt stress. The use of biochar increased net photosynthesis and transpiration, resulting in higher water use efficiency, as well as higher K⁺ concentration in the roots, leading to a lower Na⁺/K⁺ ratio. The use of biostimulant resulted in an increase in the number of leaves and in the content of chlorophyll a, b, total, and carotenoids. The results obtained with the combined use of biochar and biostimulant were not efficient in mitigating salt stress. Thus, it is understood that the combination of biochar and biostimulant did not prove effective in alleviating salt stress, and the isolated use of each strategy is recommended.