Indução de tolerância ao estresse salino em mudas de cana-de-açúcar pré-condicionadas com ácido salicílico

Abstract

Among all the adverse environmental conditions to which the plants are submitted, the salinity is among the main ones, as it causes a reduction in the yield of the crops. In view of this fact, it is necessary to create methods that favor the adaptation of plants to these conditions, one of them is the application of priming treatments before subjecting them to unfavorable environments. The objective of the present work was to promote tolerance to saline stress in pre-sprouted sugarcane seedlings of the Ridesa variety (RB92579), using salicylic acid (AS) as priming. The experimental design was DIC (completely randomized delimitation), with a factorial scheme of 3 x 3, corresponding to three levels of priming: 0mg L-1, 150mg L-1 and 300mg L-1 and three levels of saline concentrations (0 mM, 25 mM and 50 mM NaCl), where each treatment consisted of six replicates. It was applied (single application) in the plants by spraying, AS following the above treatments and after, after fifteen days the plants received the treatments with NaCl. Biometric data, such as: plant height (ALT), fresh biomass (BFA) and dry matter (BSA) and fresh radicular (BFR) and dry biomass (BSR) were measured every 10 days for 40 days. The levels of chlorophyll a, b, total, carotenoids and malondealdehyde (MDA) were also determined. Saline stress promoted reductions of ALT, BFA, BSA, but did not alter BSR, nor did the photosynthetic pigments. Priming promoted reductions in biometric parameters and increase of chlorophyll b at 300mg L-1 AS. Plants not submitted to salinity but receiving 150 mg L-1 of AS reduced BFR. The application of priming provided reductions in lipid peroxidation (MDA) and the H2O2 content acted with a ROS indication. The application of NaCl in the variety RB92579 of sugarcane did not promote oxidative stress in the plants, as a consequence of the salt stress, possibly this behavior may be associated with the low concentration of NaCl applied to the variety, making it impossible to verify effectively the application of salicylic acid as priming.