Arsenic stress on photosynthesis and growth in Ipomoea aquatica

An experiment was conducted to understand the effect of arsenic (As) on photosynthetic pigments in Ipomoea aquatica leaves, its growth performance and As uptake in edible plant parts. The experiment was designed with three levels of As treatments, viz. 10, 20, and 40 mg As kg-1 soil along with control, and three biological replications. I. aquatica was grown for six weeks after seed germination. Chlorophyll-a, chlorophyll-b, carotenoid, plant height and weight increased at lower rate of As application (10 mg kg-1) in soil. Higher As (20 and 40 mg As kg-1 soil) in soil significantly decreased all the parameters except carotenoid. Both plant height and weight were significantly reduced at 20 mg As kg-1 in soil. Chlorophyll-a and chlorophyll-b content were significantly reduced at 40 mg As kg-1 in soil. Arsenic concentration in plant parts increased significantly at higher As concentration and exceeded the maximum limit of As (0.5 mg kg-1) for vegetables at 20 mg As kg-1 soil and above. Arsenic uptake (µg plant-1) also increased significantly with elevated levels of soil As (40 mg kg-1). Considering the growth performance, I. aquatica should not be recommended to grow where the soil As concentration is 20 mg kg-1 and above