Phytoextraction Potential and Physiological and Biochemical Changes of Sunflower (Helianthus annuus) Plant in Metal Contaminated Soil

Background and aim: Heavy metals are major environmental pollutants due to toxicity and non-biodegradability. Sunflower phytoextraction is a cost-effective method for remediating metal-contaminated soils. Sunflowers, adaptable and fast-growing, show promise, but there's limited knowledge on the targeted metals and the plant's response to heavy metal stress. This study aims to uncover sunflower's phytoextraction capacity and its reaction to soil heavy metal stress.
Materials and methods: In a greenhouse experiment, Sunflower plants were grown by applying heavy metals (Zn, Cu, Ni, Pb and Cd) to the soil in order to determine the phytoextraction capacity and the physiological and biochemical changes occurring within the plant related to heavy metal applications. Soil and plant analysis were carried out in the experiment. Plant metal phytoremediation parameters and plant biochemical parameters were evaluated.
Results: Heavy metals applied to the soil in increasing amounts increased the heavy metal contents in the plant. Sunflower plant especially absorbed Pb and Cd metals at relatively high levels. Among the metals applied to the soil, Cd was determined at the highest level in the plant. The highest metal transfer factor and phytoextraction efficiency were determined for Zn, Cu and Cd metals. The dry matter amount of the plant did not change significantly with metal applications. Sunflower plants grown in soil where high levels of heavy metals were applied produced high biomass during the 5-week vegetation period after germination and did not show phytotoxicity, but a significant decrease in chlorophyll content was noted. Regarding the heavy metals applied to the soil, the amounts of proline, polyphenols and flavonoids in the plant were increased, and the highest values were determined in Pb and Cd applications.
Conclusion: Research findings have shown that the Sunflower plant is well adapted to heavy metal stress conditions and can be used as an effective phytoextraction plant.