Alleviation effects of LaCl3 on photosynthetic characteristics of cucumber seedlings under nitrate stress Effects of elevated atmospheric CO2 concentration on mung bean leaf photosynthesis and chlorophyll fluorescence parameters. Phytotoxicity of Cu2+ on Physiolodical Indices and Ultrastructural Responses in Leaves of Trapa bispinosa Roxb. Effects of Elevated Atmospheric CO2 Concentration on Soybean Photosynthesis and Chlorophyll Fluorescence Parameters