Ecofisiologia de Mesosphaerum Suaveolens (l.) Kuntze sob salinidade da água de irrigação e ácido salicílico.

Abstract

Mesosphaerum suaveolens (L.) Kuntze is a species with great exploitation potential due to its therapeutic and aromatic potential, presenting great capacity to adapt to the conditions of the Northeast region. However, its exploitation can be affected by the excess of salts contained in the soil and water used for irrigation, and it is necessary to adopt measures that attenuate the effect of saline stress. Among these measures comes the use of phytohormone as the salicylic acid that acts in the regulation of the mechanisms of vegetal defense. The objective of this study was to evaluate the effect of salicylic acid treatment of seeds as a saline stress attenuator on the germination, growth and physiology of plants of Mesosphaerum suaveolens (L.) Kuntze. For that, three experiments were carried out: In the first one the germination and the vigor of the seeds in the Laboratory of Seeds Analysis were evaluated; while in the second the growth was evaluated and the third the gas exchanges, fluorescences and indexes of chlorophylls of plants conducted in greenhouse of the Center of Agrarian Sciences, Universidade Federal da Paraíba, Areia – PB. Experiment 1 was conducted in a completely randomized design and 2 and 3 randomized blocks, the three in an incomplete factorial scheme 5 x 5, with five levels of electrical conductivity of irrigation water (ECw = 0.00, 1.45; 5.00, 8.55 and 10.0 dS m-1) and five doses of salicylic acid (SA = 0.0, 0.29, 1.0, 1.71 and 2.0 mM L-1), with four replicates, totaling in 9 combinations generated through the Central Compound matrix of Box. According to the results, the salicylic acid shows to be a promising alternative as a stimulant of the physiological quality of the seeds and in the growth of the plants under conditions of saline stress. Increasing the electrical conductivity of irrigation water significantly reduces the growth and gas exchange, fluorescence and chlorophyll indices in the plants of Mesosphaerum suaveolens (L.) Kuntze.