Tea tree (Melaleuca alternifolia) canopy was sprayed with low concentration of NaHSO3 or mixture of NaHSO3+ KH2PO4. The treatments significantly enhanced net photosynthetic rate (PN), carboxylation efficiency (CE), and the maximum response of PN to intercellular CO2 concentration. The enhancement of PN by foliar application of low concentrations of bisulfite was due to increasing CE relevant to ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase activity and regeneration rate of RuBP depending on ATP formation. and W.-J. Yang ... [et al.].