Heavy metal uptake and stress responses of hydroponically cultivated garlic (Allium sativum L.)

The accumulation of toxic metals (Cd, Co, Cu and Ni) by Allium sativum plants was followed under hydroponic conditions. The toxic metals were applied at two concentrations (0.05 and 0.25 mM). The effects of heavy metals on chlorophyll and carotenoid content, root length and amino acid exudation were examined to evaluate the impact of heavy metal accumulation on plant growth and development. A significant hyperaccumulation of cadmium by garlic roots was observed. Cobalt stimulated carotenoid production in garlic leaves. Copper accumulation was associated with increased exudation of amino acids to the cultivation medium and elevation of chlorophyll content in leaves. Nickel significantly reduced root growth.

► The heavy metals were taken up within 48 h.
► The highest accumulation was found in the roots of tested plants, copper and cobalt decreased chlorophyll and carotenoid contents in plants.
► Plants exposed to cobalt- and nickel had significantly reduced root growth.
► Plants cultivated with copper exhibited even 100 times higher amino acid exudation to the medium.