Hydrogen peroxide and salt stress in radish: effects on growth, physiology, and root quality

Abstract

Hydrogen peroxide (H₂O₂) plays a central role in responses to salt stress, a major abiotic stress that impacts crop yield worldwide. Despite the evidence that H₂O₂ mitigates salt stress and improves post-harvest quality on several species, its effects on radish were not investigated so far. Thus, the objective of this study was to evaluate the exogenous application of H₂O₂ on salt stress mitigation of radish growth, physiology, and post-harvest quality. For this, radish plants were grown in pots for 30 days, being watered with non-saline (0.31 dS m^-1) or saline water (120 mM NaCl, 12.25 dS m^-1). Plants were leaf-sprayed weekly with water (control - 0 µM H₂O₂) or H₂O₂ (150 or 1500 µM) solutions. The experimental design was completely randomized in a 3 × 2 factorial scheme (H₂O₂ treatments × salt stress conditions). The growth, physiology (gas exchanges, photochemical efficiency, relative water content, electrolyte leakage, and the contents of chlorophylls and carotenoids), and post-harvest attributes of globular roots (color, anthocyanins, vitamin C, phenolic compounds, and soluble solids) were determined. Salt stress decreased gas exchanges and increased electrolyte leakage, which resulted in stunted radish growth, and increased the contents of antioxidants, such as anthocyanins, soluble solids, and vitamin C, improving globular root quality. Conversely, H₂O₂ did not mitigate salt stress effects on radish growth, photosynthetic capacity, and oxidative damages. Although H₂O₂ increased vitamin C under non-stressed condition, it was decreased under salt stress. Thus, we conclude that H₂O₂ did not mitigate salt stress on radish growth and quality.

Supplementary information: The online version contains supplementary material available at 10.1007/s12298-024-01476-z.

Keywords: H2O2; Phenolic compounds; Post-harvest quality; Raphanus sativus; Salinity; Vitamin C.

Fig. 1

Box-plot representation of the growth parameters of 30-d-old radish plants grown under non-stressed or salt-stressed (120 mM NaCl) conditions and treated with water (control) or hydrogen peroxide (H₂O₂ – 150 and 1500 µM). The lines inside the box show the median values surrounded by lower and upper boxes indicating the first and third quartile. The vertical lines (whiskers) indicate value ranges (n = 10). Capital letters compare non-stressed with salt-stressed plants within each hydrogen peroxide level, and lowercase letters compare hydrogen peroxide concentrations within non-stressed or salt-stressed condition by Tukey’s test (P ≤ 0.05)

Fig. 2

Box-plot representation of the gas exchanges and chlorophyll fluorescence of 30-d-old radish plants grown under non-stressed or salt-stressed (120 mM NaCl) conditions and treated with water or hydrogen peroxide (150 and 1500 µM H₂O₂). The lines inside the box show the median values surrounded by lower and upper boxes indicating the first and third quartile. The vertical lines (whiskers) indicate value ranges (n = 10). Capital letters compare non-stressed with salt-stressed plants within each hydrogen peroxide level, and lowercase letters compare hydrogen peroxide concentrations within non-stressed or salt-stressed condition by Tukey’s test (P ≤ 0.05)

Fig. 3

Box-plot representation of the electrolyte leakage, Fv/Fm, and photosynthetic pigments of 30-d-old radish plants grown under non-stressed or salt-stressed (120 mM NaCl) conditions and treated with water or hydrogen peroxide (150 and 1500 µM H₂O₂). The lines inside the box show the median values surrounded by lower and upper boxes indicating the first and third quartile. The vertical lines (whiskers) indicate value ranges (n = 10). Capital letters compare non-stressed with salt-stressed plants within each hydrogen peroxide level, and lowercase letters compare hydrogen peroxide concentrations within non-stressed or salt-stressed condition by Tukey’s test (P ≤ 0.05)

Fig. 4

Post-harvest attributes of 30-d-old radish plants grown under non-stressed or salt-stressed (120 mM NaCl) conditions and treated with water or hydrogen peroxide (150 and 1500 µM H₂O₂). The lines inside the box show the median values surrounded by lower and upper boxes indicating the first and third quartile. The vertical lines (whiskers) indicate value ranges (n = 10). Capital letters compare non-stressed with salt-stressed plants within each hydrogen peroxide level, and lowercase letters compare hydrogen peroxide concentrations within non-stressed or salt-stressed condition by Tukey’s test (P ≤ 0.05)

Fig. 5

Principal component analysis and contribution of the original variables evaluated in 30-d-old radish plants grown under non-stressed (NS) or salt-stressed (NaCl) conditions and treated with water (0 µM) or hydrogen peroxide (H₂O₂ – 150 or 1500 µM). a Principal component analysis; b relative contributions of the original variables