The studied of growth, absorption and accumulation of heavy metals by sunflower (Helianthus annuus L.) grown on Cd-Zn co-contaminated solution

Abstract

This research aimed to investigate the growth and accumulation of heavy metals by sunflower grown on Cd-Zn co-contaminated solution. Sunflowers were grown with mineral solution containing Cd and Zn at different concentrations to study the effects of heavy metals on growth and selected proper concentrations that did not affect growth for further experiments. Sunflowers grew well when planted in a solution with a concentration of Cd not more than 0.5 mg/L and Zn concentration of not more than 1.25 mg/L. After that, sunflower cultivation was carried out in mineral solution containing Cd at concentrations of 0, 0.1, 0.3 and 0.5 mg/L. Each Cd concentration was added with Zn at concentrations of 0, 0.2, 0.6 and 1 mg/L for 15 days. The plants were then analyzed for growth and heavy metal accumulation. This investigation revealed that Zn, a micronutrient, inhibits plant growth and causes toxicity when received in a too high dose. The right amount of Zn can promote plant growth in Cd co-containing conditions. Increased Cd concentration in the stem would result in a decrease in the Zn concentration in the stem. Cd may affect Zn absorption and interfere with the physiological processes of plants which Zn is involved. In this study, sunflower had the ability to transport and accumulate Cd in the stem of more than 100 mg/kg dry weight. It is classified as a Cd hyperaccumulator plant.