Mitigation of Salinity Induced Morpho-physiological and Biochemical Effects by Seed Treatment with 28-Homobrassinolide in Pea (Pisum sativum L.)

Salinity is very severe global problem so a study was carried out to investigate the response of pea (Pisum sativum L.) cv. Climax seeds imbibed with 28-homobrassinolide (HBL) and sodium chloride (NaCl) before sowing. The seeds soaked in two different concentrations of HBL (5 and 10 µM) for 4 hours, caused an increase in most of the aspects of shoot and root growth both at seedling stage and mature stage (90 days after sowing). At seedling stage, HBL (10 µM ) significantly enhanced the fresh biomass by 19%, dry biomass by 31%, seedling height (shoot+root) by 14%, photosynthesis rate by 29%, stomatal conductance by 18%, total chlorophyll contents by 43%, superoxide dismutase (SOD) by 39%, nitrare reductase activity (NRA) by 28% and nitrite reductase activity (NiRA) by 29% in comparison to control (water soaked alone). However, at mature plant stage the plants grown from seeds pre-imbibed in HBL (10µM) possessed 14% and 27% higher leaf NR and NiR activities, 23% increase in dry mass, 51% enhancement in nodule number, and 20% increase in nodule dry biomass, in comparison to water imbibed, control. Antioxidant enzyme superoxide SOD was 66% higher than control. The 28-homobrassinolide enhanced the photosynthesis rate (28%), stomatal conductance (31%), chlorophyll a (48%) and chlorophyll b (59%) as compared to the control. It was concluded that salinity induced drastic effects can be mitigated by the seed treatment with 28-homobrassinolide.