Abstract

Rising salt concentration in water induces osmotic stress and ionic toxicity, compromising photosynthesis, growth, and survival of threatened species such as Paubrasilia echinata and highlighting the need for stress-mitigating compounds such as salicylic acid. This study evaluated the effect of salicylic acid on the morphophysiological responses of P. echinata seedlings irrigated with saline water. Treatments were arranged in a 2 × 3 factorial scheme, with two electrical conductivity levels of irrigation water (0.5 and 6.0 dS m−1) and three salicylic acid concentrations (0, 2, and 3 mM), randomized across 24 experimental plots containing five plants each in a randomized complete block design. Analyses included growth, relative water content, chlorophyll indices and fluorescence of seedlings. Irrigation water with an electrical conductivity of 6.0 dS m−1 reduced leaf number by 9.09% and PSII efficiency by 26.94%. Under saline conditions, salicylic acid at 2 and 3 mM increased root dry matter by 49.28% and 60.29%, respectively. The highest total chlorophyll index (79.03) was obtained at 2 mM, whereas leaf area peaked at 734.74 cm2 per plant at 3 mM. Salicylic acid enhances salt tolerance in P. echinata. At 2 mM, it improves seedling morphophysiological traits and may support restoration in salinized sites.

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