The effects of heavy metal salts on the phytohormonal status and sex expression in marijuana

Abstract

We studied the effects of heavy metal salts (Pb(NO3)2, CuSO4, and ZnSO4) on phytohormonal status and sex expression in various cultivars of marijuana (Cannabis sativa L.), a dioecious plant, grown on Knop nutrient medium. Pb(NO3)2 and ZnSO4 were added to the medium at the concentration of 10−9 M, and CuSO4, at the concentration of 10−10 M. Plant were grown under controlled conditions at luminescent illumination, 22–24°C, and 80% humidity. The contents of GA and zeatin were determined by HPLC. Copper and zinc salts induced plant feminization, and this effect was coupled with zeatin accumulation. Lead salts favored plant masculinization coupled with GA accumulation. Thus, a shift in sex expression in marijuana plants was correlated with the heavy metal action on the balance of phytohormones, GA and zeatin.