Effects of La3+ on Tissue Culture of Gerbera jasmesonil ‘Sunbird’ Effects of Salt Stress and La3+ on Antioxidative Enzymes and Plasma Membrane H+-ATPase in Roots of Two Rice Cultivars with Different Salt Tolerance Effects of La3+ on Tissue Culture of Gerbera jasmesonil ‘Sunbird’ Effect of La on Ca content in tobacco callus and oilseed rape seedling root