Ascorbic acid-mediated enhancement of antioxidants and photosynthetic efficiency: A strategy for enhancing canola yield under salt stress

Ascorbic acid (AsA), a water-soluble antioxidant, act as cofactor for enzymes that regulate photosynthesis, hormonal and antioxidant biosynthesis that enables the plants to alleviate the harmful effects of salinity stress. The study was aimed to investigate the ameliorative role of foliar application of 200 ppm ascorbic acid (AsA) in improving growth by changing antioxidant response, photosynthetic capacity and mineral nutrient status of two canola varieties (Dunkled and Cyclone) under salinity stress (200 mM NaCl). Salt stress reduced plant biomass, photosynthetic activity, and accumulation of macro and micronutrients such as K+, + , Ca2+and 2+ and Zn2+ 2+ in both canola varieties, on the other hand accumulation of Na+ + and Cl-was- was increased. The salinity- induced oxidative stress (H2O2 2 O 2 and MDA) caused photoinhibition of PSII at the donor and acceptor ends. The salinity-induced reduction in efficiency of electron donation to PSII (Fv/Fo) and electron transport through PSII (Fm/Fo), especially in Cyclone, significantly reduced ETRII thus enhancing CEF around PSI and NPQ in both canola varieties that has been considered as photo-protective mechanism of plants. In addition, salt stress enhanced CEF around PSI. However, application of AsA improved the structural stability of PSII, linear electron transport and reduced donor end limitation of PSI activity by improving electron transfer from PSII to PSI. The application of AsA improved the stomatal conductance, inter-cellular CO2 2 concentration and net CO2 2 assimilation rate thereby resulting in improved consumption of extra-electrons in CO2 2 fixation generated by photosynthetic electron transport. Exogenous AsA application reduced the oxidative stress and improved the antioxidant potential by managing extra-electrons produced in CO2 2 fixation. All these physiological and biochemical changes due to AsA application helped the canola plants to improve growth and yield under salinity. Thus, the application of ascorbic acid has the potential to ameliorate the detrimental effects of NaCl stress on canola plants. (c) 2024 SAAB. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.