Effects of Organic Acids on Chlorophyll Contents and Photosynthesis of <i>Fraxinus mandshurica</i> Seedlings

By simulating oxalic and citric acid concentrations in forest litter leachates,a series of experiments were conducted to study the effects of oxalic acid and citric acid solutions on chlorophyll contents and photosynthesis of Fraxinus mandshurica seedlings.It resulted that, organic acids of appropriate concentrations increased chlorophyll contents, chlorophyll a and chlorophyll b contents varied more than carotenoid content, and 1.0mmol/L solution was best. To photosynthesis, the variability treads of net photosynthetic rates with organic acids were probably consistent to those with distilled water, but the values all increased, and 5.0mmol/L solution was best. Effects of different organic acids on chlorophyll contents and photosynthesis followed the series: citric acid >oxalic acid, and it might be relative to chemical structure, dissociation constants and organic ligand-metal stabilities of two kinds of organic acids.