Evaluation of Chromium Toxicity on Growth, Physiological Activity and Yield Potential of Sunflower (Helianthus annuus L.) Plants; An Emphasis on Phytoremediation

Metal pollution is a key environmental issue across the globe. Our environment is seriously under the threat of different heavy metals including As, Cr, Cd, Cu, Hg, Ni, Pb, and Zn. Heavy metals upon exceeding safe limits become part of food chain and affect growing plants and consumers; and ultimately affect consumer’s health at large. Amongst, since long chromium is widely used metal in different industries like tannery, textile, fertilizers, electroplating, steel etc. and has become a serious environmental and agricultural pollutant. Present investigation has been set to evaluate chromium toxicity in sunflower test varieties along with phytoremediation potential of these test varieties. Chromium application in the soil (50-500 mg/kg) found to be toxic for germination time, plant growth and biomass. Different photosynthetic parameters were negatively affected under Cr stress. Likewise, the content of chlorophyll and protein were also decreased significantly following decrease in plant minerals (NPK and Mg). However, sunflower varieties were able to accumulate proline content showing their osmolyte accumulation strategy against Cr metal. Different yield parameters were assessed under Cr treatment. A declining trend in seed yield and harvest index was observed. Cr effect was increasing with its increased level in the soil medium. Both varieties revealed the toxic effect of Cr metal, however, both showed a higher Cr uptake potential from the contaminated soil. This shows sunflower varieties to be a good phytoremediation tool.