Salicylic acid on gas exchange and growth of Hymenaea courbaril L. seedlings under flooding ¹

Ácido salicílico nas trocas gasosas e crescimento de mudas de Hymenaea courbaril L. sob alagamento

HIGHLIGHTS:

Flooding damages the gas exchange of Hymenaea courbaril seedlings.

Foliar application of salicylic acid stimulates the initial growth and quality of H. courbaril seedlings.

Physiological variables present greater phenotypic plasticity than growth characteristics.

ABSTRACT

Flooding is a stressful condition that causes damage to the photosynthetic apparatus, negatively affecting the growth of seedlings of fruit species, including Hymenaea courbaril L. Studies on physiological management, such as exogenous application of phytohormones, to alleviate abiotic stress have increased. The objective of this study was to evaluate the effect of foliar application of salicylic acid (SA) on H. courbaril seedlings subjected to flooding. The seedlings received foliar application of four concentrations of SA (0, 100, 200, and 400 mg L^-1) and were subjected to two water regimes: a) control - non-flooded and irrigated daily and b) flooded - seedlings were placed in a plastic pool, keeping the water depth at ± 5.0 cm above the substrate level. After 35 days, we evaluated the gas exchange, initial growth, quality, and potential ecological resilience of the seedlings. All flooded seedlings survived, but had reduced photosynthesis, carboxylation of Rubisco efficiency, and water-use and stomatal conductance when they received 100-300 mg L^-1 SA. The seedlings that received between 100 and 300 mg L^-1 SA had greater growth, quality, and phenotypic plasticity. Foliar application of SA did not mitigated the effect of flooding on gas exchange but contributed to the growth of H. courbaril seedlings.

Key words:
Hymenaea courbaril L. (‘Jatobazeiro’); photosynthetic metabolism; phenotypic plasticity; physiological adjustments; abiotic stress