Silicon effects on aluminum toxicity to mungbean seedling growth

Abstract

The effects of silicon (Si) on the toxicity of aluminum (Al) to mungbean (Phaseolus aureus Roxb.) seedlings were studied in a growth chamber. Mungbean seedlings were grown in a nutrient solution with combinations of three concentrations of Si (0,1, and 10 mM) and three concentrations of Al (0, 2, and 5 mM) in randomized completely block design experiments for 16 days. Silicon at 1 mM in the solution decreased root length, fresh and dry weights, and chlorophyll content, and showed no significant effect on epicotyl length and seedling height, and protein contents of shoots or roots in mungbean seedling under no Al stress. But, Si at 10 mM showed marked toxic effects on mungbean seedling growth and increased protein contents of the shoots or roots. In contrast, under 2 mM Al stress, Si addition at 1 mM had significant increasing effect on root length, fresh and dry weights, and chlorophyll content. It also had decreasing effect on protein contents of the shoots or roots, and had no effect on epicotyl length and seedling height. Silicon addition at 10 mM showed no effect on morphological and physiological measurements of mungbean seedling. However, Si at 1 mM added to solution only increased seedling height, epicotyl length, fresh weight, and chlorophyll content, but decreased dry weight and protein content of the roots under 5 mM Al stress, significantly. Silicon addition at 10 mM showed similar toxic effects on mungbean seedling growth under 5 mM Al stress to that under no Al stress.