Salinity and exogenous H₂O₂ improve gas exchange, osmoregulation, and antioxidant metabolism in quinoa under drought stress

Abstract

Climate change‐induced concurrent drought and salinity stresses significantly threaten global crop yields, yet the physio‐biochemical responses to combined stress in quinoa remain elusive. This study evaluated quinoa responses under four growth conditions: well‐watered, drought stress, salt stress, and drought + salt stress with (15 mM) or without (0 mM) exogenous hydrogen peroxide (H2O2) application. All examined stresses (alone or in combination) reduce quinoa growth and net photosynthesis, although salt stress was found to be less destructive than drought and combined stress. Strikingly, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), stomatal conductance (gs), photosynthetic rate (PN), K+ uptake, shoot height, shoot fresh, and dry weight were increased by 46.1%, 22.2%, 101.6%, 12.9%, 12.1%, 22.4%, 7.1%, 14%, and 16.4%, respectively, under combined stress compared to drought alone. In addition, exogenous H2O2 effectively improved gaseous exchange, osmolytes' accumulation, and antioxidant activity, resulting in reduced lipid peroxidation, which eventually led to higher plant growth under all coercive conditions. The principle component analysis (PCA) indicated a strong positive correlation between antioxidant enzymes and inorganic ions, which contributed efficiently to osmotic adjustment, particularly under conditions of salinity followed by combined stress. In short, in combination, salt stress has the potential to mitigate drought‐induced injuries by promoting the absorption of inorganic solutes for osmoregulation in quinoa plants. Furthermore, exogenous application of H2O2 could be opted to enhance quinoa performance to increase its tolerance mechanism against drought and salinity, even under combined stress.

Redox priming could be an appropriate technique to minimize drought-induced adversities in quinoa

“…The effect of drought on quinoa performance depends on the variety and degree of stress and is also influenced by other environmental factors. Results revealed that drought stress reduces quinoa growth and yield in the present study, and these results correspond with previous studies ( Huan et al., 2022 ; Mahdavi Rad et al., 2022 ; Abbas et al., 2023 ; Iqbal et al., 2023 ). However, H 2 O 2 application significantly improved growth attributes, chlorophyll contents, antioxidant enzyme activities, osmolyte accumulation (proline, TSP, and GB), and reduced MDA contents ( Tables 3 , 4 ; Figures 3 , 4 ), ultimately resulting in increased drought tolerance.…”

Genome‐wide characterization of trihelix genes reveals Cqtrihelix23 enhances the salt tolerance in quinoa (Chenopodium quinoa)

“…Furthermore, reports suggest that salt stress may alleviate drought damage in quinoa by facilitating the absorption of inorganic solutes for osmotic regulation. Additionally, exogenous application of H 2 O 2 has been found to enhance quinoa's tolerance to both drought and salt stress (Iqbal et al, 2023). It has also been observed that moderate salt stress can stimulate quinoa growth, although the combined treatment of potassium deficiency and salt stress has been shown to significantly reduce stomatal density, stomatal aperture, and biomass (Waqas et al, 2021).…”