Protective role of selenium on pepper exposed to cadmium stress during reproductive stage

The aim of the present study was to examine the effects of exogenous selenium (Se) supplementation on the tolerance of pepper (Capsicum annuum L.) cv. Suryamukhi Cluster plants to cadmium (Cd) phytotoxicity at the reproductive stage. The pepper plants were supplied with Cd (0, 0.25 or 0.50 mM) and Se (0, 3 or 7 μM), individually or simultaneously, three times during the experiment. The obtained results show that Cd had deleterious effect on pepper plants at the reproductive stage. However, Se supplementation improved the flower number, fruit number and fruit diameter in plants exposed to 0.50 mM Cd. Moreover, both Se concentrations used in 0.25 mM Cd-treated plants and 3 μM Se in 0.50 mM Cd-treated plants enhanced fruit yield per plant as compared to Cd-alone treatment. The chlorophyll concentrations significantly increased in the fruits of Cd-exposed plants after Se addition. However, Se supplementation reduced total carotenoids and total soluble solid (TSS) concentrations in the pepper fruits exposed to Cd. Selenium also generally enhanced the total antioxidant activity of pepper fruits subjected to Cd. Both Se concentrations used increased mean productivity (MP), stress tolerance index (STI) and yield stability index (YSI) in plants grown in the medium containing 0.25 mM Cd. At low concentration (3 μM), Se significantly increased geometric mean productivity (GMP), STI and YSI of plant exposed to 0.50 mM Cd. The highest Cd concentration in the fruits was achieved at 0.50 mM Cd and Se application significantly reduced Cd accumulation in the Cd-exposed plants. Our results indicate that application of Se can alleviate Cd toxicity in pepper plants at the reproductive stage by restricting Cd accumulation in fruits, enhancing their antioxidant activity and thus improving the reproductive and stress tolerance parameters.