Effect of citric acid on antioxidant activity of red bean (Phaseolus calcaratus L.) under Cr+6 stress

Abstract

Chromium-VI imposed harmful morphological, physiological, and metabolic effects in plants. Soil pollution from heavy metals is one of the foremost discussed to cause the deficiency of safe food. This study aimed to research the impact of citric acid (0, 2.5 and 5 mM), singly or together, on plant growth, photosynthetic pigments, total chlorophyll, carotenoids, anthocyanine, DPPH activity, chromium uptake and translocation factor (TF) of red bean exposed to chromium-VI stress (0, 1 and 10 mM). Results showed that shoot and root lenth, fresh and dry weight, chlorophyll, carotenoids, and DPPH activity decreased under chromium, while anthocyanine increased. The increasing concentration of chromium also enhanced the chromium uptake and accumulation in plant shoota and roots. This study showed that the addition of citric acid with chromium significantly enhanced shoot and root length, fresh and dry weight, chlorophyll, carotenoids, anthocyanine, and DPPH activity in plants. The citric acid decreased the concentration and accumulation of chromium in plant shoots and roots. This means that the most increase in translocation factor value was recorded under the combined application of chromium 1 mM and citric acid 2.5 and 5 mM, as compared to the plants treated with chromium alone. It is concluded that the red bean can be a potential candidate for phytoremediation of chromium contaminated soils. Hence, the citric acid played this role through the regulation of the antioxidant system to diminish the toxicity of Chromium-VI.