Abstract
It has been well documented that phytohormones plays a pivotal role in combating ill effects of various abiotic stresses in crop plants. Out of various phytohormones, worldwide researcher has recognized salicylic acid as potent stress alleviator through modulation in plant metabolic processes. Therefore, present study was designed with an aim to dissect out the role of salicylic acid (through seed) mediated amelioration of heavy metal stress in the presence and absence of kinetin or calcium in Phaseolus vulgaris plants. Seeds were soaked in salicylic acid (0.1 mM) either alone or in combination with kinetin (30 ppm) or calcium chloride (40 mM) before sowing and then seedlings were exposed to toxic concentration of nickel (2.5 mM) and lead (0.5 mM). Salicylic acid alone and in combination with kinetin or calcium improved growth traits, photosynthetic pigment, carbohydrate contents, and nitrogenous constituents along with activities of carbonic anhydrase, nitrate reductase, catalase, peroxidase, and superoxide dismutase of Phaseolus vulgaris plants. However, nickel and/or lead showed oxidative damage through increased electrolyte leakage, malondialdehyde and reduced uptake of mineral ions. Moreover, plants raised from seeds soaked in salicylic acid in combination with kinetin or calcium showed enhanced activities of antioxidant enzymes and proline accumulation under nickel and/or lead stress in Phaseolus vulgaris plants. This study revealed the efficiency of pre-sowing seed soaked in salicylic acid either alone or in alternate combination with kinetin and calcium on neutralizing the toxic effect generated from nickel and/or lead in Phaseolus vulgaris plants and could be employed as sustainable agricultural technique in removal of nickel and lead stresses from plants.
•Polluted soils showed excessive level of essential elements that can be toxic to crop plants.•Nickel has more inhibitory influence on the growth and the determined metabolic activities than lead.•Salicylic acid in combination with kinetin and/or calcium ameliorates heavy metals toxicity in Phaseolus vulgaris.•Salicylic acid could be exploited to overcome the heavy metal toxicity in plants through improved antioxidant system.