Salt-tolerance in Vicia faba L. is mitigated by the capacity of salicylic acid to improve photosynthesis and antioxidant response

Abstract Selection and improvement of crops subjected to salinity constitutes an urgent need for increasing agricultural and food production in order to feed the growing human population. The aim of the present study is to evaluate the role of salicylic acid (SA) application in mitigating the adverse effects of salinity on faba bean (Vicia faba L.) at the physiological and molecular levels. Fort this purpose, two faba bean genotypes were subjected to various concentrations of NaCl and salicylic acid in a full factorial design. After that, growth, water status, gas exchanges, photosynthesis parameters, ions homeostasis and antioxidant enzymes activities were evaluated. The obtained results demonstrated that salinity induced several limitations in plants growth and physiological attributes. In response, salt stressed faba bean plants improved water status and enhanced antioxidant enzymatic activities. Remarkably, salt-tolerance of both genotypes was significantly improved by salicylic acid application which allowed the maintenance of cell membrane and photosynthetic process, restoring of ion homeostasis and the diminution of oxidative damages. Overall, the difference between genotypes is rather quantitative than qualitative even if the genotype Aguadulce displayed better growth, physiological and molecular response under salt stress than the genotype Histal. Besides, the beneficial effects of salicylic acid vary according to its concentration, the tested genotype and the studied parameter; the genotype Aguadulce performs better under the treatment with 0.5 mM SA while the genotype Histal manifests greater behaviour under the treatment with 1 mM SA. Therefore, salicylic acid can be considered as potential growth regulator to improve the salt response of faba bean. The application of salicylic acid would provide a practical basis for wide cultivation of faba bean in marginal and wastelands under-cultivated and might propose an effective ecological and economical alternative solution to deal with salt-affected soils mainly in arid regions.