Brassinosteroid (24-epibrassinolide) enhances growth and alleviates the deleterious effects induced by salt stress in pea (Pisum sativum L.)

The response of pea (Pisum sativum L.) cv. Climax seeds imbibed with 24-epibrassinolide (EBL) and sodium chloride (NaCl) prior to sowing was evaluated. Soaking of seeds in two different concentrations of EBL (5 and 10 mu M) for 4 hours, caused an increase in germination, embryo axis length and most of the aspects of shoot and root growth at seedling stage, maturity stage (90 DAS) along with seed yield at the time of harvest. Both the EBL treatments (5 and 10 mu M) improved the above mentioned attributes but maximum improvement was observed in response to EBL concentration of 10 mu M with respect to the control. At seedling stage, EBL (10 mu M) significantly enhanced the fresh and dry biomass, seedling height (shoot + root), photosynthesis rate (Pn), stomatal conductance (g(s)), total chlorophyll contents (Chl), proline contents, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), nitrate reductase activity (NRA) and nitrite reductase activity (NiRA) as compared to control (water soaked alone). Similarly, at maturity stage the plants grown from seeds pre-imbibed in EBL (10 mu M) also exhibited the augmentation in dry biomass, physiological aspects (Pn, g(s) and Chl), enzymatic activities (NRA, NiRA, SOD, POD, CAT), leaf proline contents, nodule number and nodule dry biomass in comparison to water imbibed control. Seed attributes like seed yield, seed number and seed protein contents also showed the improvement in response to EBL (10 mu M) at the time of harvest. Although, plants subjected to saline stress exhibited a reduction in all the morpho-physiological and enzymatic attributes (NRA and NiRA) but proline contents and enzymatic activities of antioxidants were enhanced in response to NaCl stress. However, deleterious effects induced by salinity were reduced if seeds were treated with EBL before or after NaCl imbibitions.