Comparative and interactive response of salicylic acid, 24–epibrassinolide or sodium nitroprusside against cadmium stress in Linum usitatissimum

Concerns regarding the effects of heavy metals (HMs) on agricultural productivity have grown over time. Because HM stress disrupts a number of the plants' physiological-biochemical and metabolic processes, it severely limits production. Phytohormones can effectively improve plants resistance to HM stress. This work was done to examine the comparative effectiveness of salicylic acid (SA), 24–epibrassinolide (EBL) and sodium nitroprusside (SNP) on photosynthetic attributes, growth, antioxidant enzymes activity in Linum usitatissimum cv. RLC–6 (flax) subjected to cadmium (Cd) stress during vegetative growth stages. Cd considerably decreases the length, biomass, leaf diameter, chlorophyll content, and photosynthetic traits; and further triggered ROS and MDA content in plant. Moreover, exogenous application of SA, EBL and SNP individually and in combination improved the antioxidant enzymatic machinery by increasing the levels of superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT) and decrease the superoxide, hydrogen peroxide, scavenges ROS and MDA accumulation. Furthermore, submission of phytohormones also caused proline to accumulate and the activities of carbonic anhydrase (CA) and nitrate reductase (NR) to be activated which were impaired due to Cd stress. Among the phytohormones, the most effective method for dropping the damaging impacts of Cd and promoting plant growth and development was EBL. However, combined application of all three phytohormones (SA + EBL + SNP) proved to be the best. Thus, it can be concluded that, these augmented activity of antioxidants and proline elicited by application of phytohormones, would have continued to be able to give Linum usitatissimum exposed to Cd stress resistance.