The objective of this article is to study the effect of 5-aminolevulinic acid (ALA) and enhanced chlorophyll content, antioxidative enzymes and photosynthesis rate by foliar application of ALA. We evaluated three concentrations (control-distilled water, T1-50 mg l⁻¹, T2-150 mg l⁻¹, T3-250 mg l⁻¹) of ALA and seven cultivars, ‘‘Sanchidaye’’ (Sa-1), ‘‘Lichuandasuomian’’ (Li-1), ‘‘Aijiaohuang’’ (Ai-1), ‘‘Qingyou’’ No. 4 (Qi-1), ‘‘Aikang’’ No. 5 (Ak-1), ‘‘Hanxiao’’ (Ha-1) and ‘‘Shulv’’ (Sl⁻¹). ‘‘Ak-1’’ showed strongest response of POD (peroxidase) enzyme activity (0.4 U g⁻¹ min⁻¹) in 250 mg l⁻¹ ALA solution. The highest CAT (catalase) activity (0.8 U g⁻¹ min⁻¹) after administration of 250 mg l⁻¹ ALA was observed in ‘‘Li-1’’. Meanwhile, highest (1.42 mg l⁻¹) total chlorophyll content was also observed in ‘‘Ak-1’’, when leaves were treated in 50 mg l⁻¹ ALA, ‘‘Li-1’’ and ‘‘Ai-1’’ showed strongest response of specific activity of superoxide dismutase (SOD) in 50 mg l⁻¹ and 50 mg l⁻¹ ALA. Two hundred and fifty milligram per milliliter of ALA-treatment significantly improved the net photosynthetic rate.