Effect of citric acid on aluminum toxicity in the growth of mungbean seedlings

Abstract

Citric acid was reported to chelate aluminum (Al) strongly and alleviate Al toxicity. Detoxification of Al by adding citric acid was studied in experiments with mungbean (Phaseolus aureus Roxb.) seedlings and cuttings (without roots) grown in a growth chamber. The seedlings and cuttings were grown for sixteen days in a dilute nutrient (pH 4.1) at two concentrations of citric acid (0, 5 mM) and three concentrations of Al (0, 2, and 5 mM) using a complete randomized design method. Results showed that 5 mM citric acid increased the height of mungbean seedlings, length of epicotyl, and fresh weight of seedlings and roots significantly. Although the mitigation by adding citric acid was more effective at higher Al concentrations, it seemed that citric acid was harmful to fresh and dry weights of cuttings under higher Al stress. This was perhaps attributed to the absence of roots. The content of soluble protein and chlorophyll in the seedlings were decreased under high Al stress by adding citric acid, but were unaffected in the cuttings at 2 mM Al. This also implied that alleviation of Al toxicity by adding citric acid was related to the root function.