Growth stage and molybdenum treatment affect cadmium accumulation, antioxidant defence and chlorophyll contents in Cannabis sativa plant.

Cadmium (Cd) uptake and accumulation in plant tissues is affected by physiological stage of a plant and presence of mineral nutrients in soil. We investigate the effect of micronutrient Mo (0.5, 1.0 and 2.0 ppm) on biomass, Cd accumulation, photosynthetic pigments and endogenous phenolics and soluble proline in Cannabis sativa plant grown in 25 and 50 ppm Cd polluted soil. Molybdenum was applied as seed soaking and soil addition treatments. The plants were harvested in two stages i.e. vegetative (6 weeks) and reproductive stages (12 weeks). It was found that seed soaking treatment of 1.0 ppm Mo most significantly increased biomass, Cd accumulation (1.76 ± 0.19 mg Cd/DBM) and phenolics (104.5 ± 4.46 ppm) concentration in the plant tissues. Molybdenum treatments highly increased Cd bio-concentration at reproductive stage as compared to vegetative stage in plants grown in 50 ppm Cd polluted soil. Translocation of Cd from roots into leaves was significantly increased by Mo treatments at reproductive stage as compared to vegetative stage. Strong inter-correlations existed between total phenolics, Cd accumulation, dry biomass and chlorophyll contents of the plant.