Growth and fluorescence rates of Mesosphaerum suaveolens (L.) Kuntze under saline stress and salicylic acid doses

Abstract

Mesosphaerum suaveolens (L.) Kuntze is a species of high phytotherapeutic and aromatic potential and quite widespread in Northeastern Brazil. However, the scarcity of good quality water and the high content of salts contained in the soil and irrigation water of the semi-arid region can compromise the crop growth and yield . Therefore, this study aimed to evaluate the effect of seed treatment with salicylic acid on the growth rates and the fluorescence indexes of chlorophyll ‘a’ from M. suaveolens plants irrigated with saline waters. The experiment was conducted in a randomized complete block design with a 5 x 5 incomplete factorial design, with five electrical conductivities of the irrigation water (ECw = 0.5, 1.45, 5.00, 8.55 and 10.0 dS m-1) and five salicylic acid doses (SA = 0.0, 0.29, 1.0, 1.71 and 2.0 mM L-1), generated by the Box Central Compound matrix. The evaluated variables were the absolute and relative growth rates for stem height and diameter and the indexes of fluorescence and quantum yield of photosystem II. The salinity of the water reduces the growth and the fluorescence indexes of the plants. The seeds treatment with salicylic acid at the doses of 1.99 and 0.69 mM L-1 attenuates the damaging effect from saline stress on the absolute and relative growths for the stem diameter.