Condicionamento osmótico e seus efeitos em Piptadenia retusa (Jacq.) P.G. Ribeiro, Seigler & Ebinger sob estresse salino.

Abstract

Salinity is one of the factors that most affect plant growth and productivity, and the search for alternatives that allow the use of saline water has become constant, and among the alternatives is the use of salicylic acid. Therefore, this study aimed to investigate the effects of salinity on stomatal behavior and growth of seedlings of the species Piptadenia retusa, as well as to analyze the role of salicylic acid in mitigating these effects. The experiment was conducted at the Forest Nursery of the Academic Unit of Forestry Engineering (UAEF/CSTR/UFCG), Patos, Paraiba, Brasil, in 8Leonard9 pots, using washed and sterilized coarse sand as support for the plants. The treatments were distributed in a completely randomized design, in a 4 x 4 factorial, consisting of four salicylic acid concentrations (0; 0.25; 0.50 and 1.0 mM) and four solution salinity levels (electrical conductivity-E.C.) (0; 2.0; 4.0 and 6.0 dS m-1). The saline treatments were obtained through the use of NaCl solutions, with the E.C. adjusted with a conductivity meter, and the control treatment consisted of tap water, with E.C. of 0.5 dS m-1. The saline treatments began at 30 days after emergence (DAE), and the experiment ended at 90 DAE. The following parameters were evaluated: transpiration rate, stomatal conductance, photosynthesis rate, intrinsic water use efficiency, plant height, stem height and diameter, height/diameter ratio; dry mass of leaves, stem, shoot, roots, total, root/shoot ratio, and total dry mass. The salinity of the nutrient solution above 4.0 dS m-1 negatively affected gas exchange and plant height of jurema-branca, while mass production was reduced at salinities above 2.0 dS m-1. Seed priming with salicylic acid attenuated the effects of salinity on gas exchange, growth and dry mass production of plants, especially at the dose of 0.5 mM.