Exogenous application of gibberellic acid and silicon to promote salinity tolerance in pea (Pisum sativum L.) through Na+ exclusion

Salinity is a worldwide problem limiting the plant growth and risking food security. This study was conducted to examine exogenous application of silicon (Si), gibberellic acid (GA₃) upon the ion transport, growth, yield, and antioxidant enzymes activities of pea plant in saline conditions. Two pea varieties Meteor-FSD and Samrina Zard were pre-treated with GA₃ (10^-4 M) for 12 h. Plants were allowed to grow with or without silicon in washed silica sand. Ten days old seedlings were shifted in pots with 10 kg soil. Twenty-five days old plants were exposed to 0 and 5 dS m^?1 sodium stress. Results showed that exogenous application of GA₃ + Si was the best treatment for increasing plant biomass and yield in the presence and absence of NaCl. Furthermore, application of Si or GA₃ enhanced chlorophyll content in the leaves, thereby increasing the net assimilation rate of pea varieties under NaCl stress by increasing the antioxidant enzyme activity. Treatment of Si alone or in combination with GA₃ significantly reduced Na⁺ movement in both pea varieties. Results showed that Si has more prominent role than GA₃ alone to build-up high plant biomass, yield, soluble protein content and reduction of Na⁺ transport. Samrina Zard variety showed higher yield, shoot and root dry weight as compared to Meteor-FSD variety in presence and absence of salt. It was concluded that Si can be used as a nutrient for pea under saline or non-saline conditions. Moreover, application of GA₃ has a potential role for increasing salinity tolerance, mostly in sensitive pea varieties.