Effects of citric acid on soybean seedling growth under aluminum stress
2004
Abdullahi, B.A. | Huang, P. | Bao, D.P. | Meng, X.Y. | Jiang, B.H. | Zhu, J. | Shen, H.G. | Yang, Y.H.
Aluminum (Al) is the major constraint for crop production in acidic soils. Soybean is a widely planted crop that can play an important role in soil improvement through natural nitrogen fixation in its roots. Little is known about the effects of exogenous citric acid (CA) on the growth of soybean seedlings under Al stress. In the present study, soybean seedlings were grown in solution with combined concentrations of Al (0, 2, and 5 mM) and CA (0 and 5 mM) in a factorial design experiment for 15 days, to evaluate effects of CA on alleviation of Al toxicity. At 2 mM Al, CA was found to alleviate Al stress by increasing epicotyl length, seedling height and root length of soybean seedlings by 11-26% (Al2 CA5 vs. Al2 CA0). Citric acid increased fresh weight by 8%, had no significant decrease on dry weight, but significantly decreased chlorophyll content by 16% (Al2 CA5 vs. Al2 CA0). At 5 mM Al, CA markedly increased epicotyl length, seedling heights and root length by 19-60%; increased fresh weight by 12%; and also decreased chlorophyll content by 9% (Al5 CA5 vs. Al5 CA0). Citric acid itself exerts virtually no promotive effect on the growth of soybean seedlings in the absence of Al. Citric acid appears to only ameliorate the Al toxicity, resulting in promoted growth of soybean seedlings.
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