Metil jasmonato atenua os efeitos da salinidade em pimenta biquinho (Capsicum chinense) e melhora os parâmetros nutracêuticos dos frutos

Abstract

Biquinho pepper (Capsicum chinense Jacq.) is valued for its flavor and nutraceutical properties. Despite its great economic potential, little is known about its responses to salinity strategies and stress mitigation, such as the use of methyl jasmonate (MeJa). This study hypothesized that MeJa could reduce salt-induced stress by improving photosynthesis, limiting oxidative damage, and preserving yield and fruit quality. To test this, biquinho pepper (‘Iracema’) plants were grown in a completely randomized design in a 3 × 3 factorial scheme combining salinity and MeJa treatments. Salt concentrations corresponded to 0 (no NaCl), 40 mM (moderate NaCl), and 80 mM (severe NaCl), while MeJa treatments corresponded to 0 (control), 0.1 mM, and 1 mM MeJa. Gas exchange parameters, plant height, number of fruits, plant height, number of leaves, leaf fresh mass, stem fresh mass, root fresh mass, stem dry mass, root dry mass, leaf dry mass, evapotranspiration, stomatal conductance, CO₂ assimilation, internal CO₂ concentration, chlorophyll a, chlorophyll b, total sugars, reducing sugars, phenolic compounds, soluble solids, flavonoids, anthocyanins, maximum quantum yield of PSII (Fv/Fm), minimum fluorescence (F₀), maximum fluorescence (Fm), variable-to-minimum fluorescence ratio (Fv/F₀), time to reach Fm (Tm), JIP-test points (O, J, I, and P), electrolyte leakage, water use efficiency (WUE), internal CO₂ concentration, intrinsic water use efficiency (iWUE), and intrinsic carboxylation efficiency (iCE) were determined. Salinity induced oxidative imbalance and impaired plant growth, with 80 mM NaCl resulting in the lowest growth. In addition, both salt concentrations induced floral abortion, completely preventing fruit production. MeJa decreased electrolyte leakage in treated plants, stimulating growth under 0 and 40 mM NaCl, but not under 80 mM NaCl, where it even reduced growth. MeJa did not reverse the inhibition of fruit production caused by salinity. In non-salttreated plants, both MeJa concentrations reduced total fruit mass, with 1 mM MeJa improving fruit quality by increasing anthocyanin, sugar, and soluble solid concentrations. Thus, 0.1 mM MeJa alleviated oxidative damage and growth restrictions in biquinho pepper under moderate salinity, but neither MeJa concentration mitigated the saline effects on fruit production.