Liu, L., Wang, Z., Zhao, X., Nan, L., Nan, H., Wang, S. and Li, H. 2015. Effects of different photorespiration inhibitors on photosynthetic characteristics and berry quality of Vitis amurensis Rupr. Can. J. Plant Sci. 95: 417-426. The effects of two photorespiration inhibitors on photosynthetic characteristics and berry quality of Vitis amurensis Rupr. were studied. The experiments used V. amurensis variety ‘Shuang hong’ as the experimental grape, NaHSO₃ (sodium bisulfite) and isoniazide (INH) as the photorespiration inhibitors with three different spray concentrations, respectively. Results show that both photorespiration inhibitors improved the soluble solids (SS) contents and SS/total acid (TA) ratios (except the 350 mg L^-1 INH treatment) in V. amurensis berries; two inhibitors can also improve the concentrations of glucose, sucrose, arabinose, lactose as well as monosaccharides (MS) and MS disaccharides (DS) contents, and at the same time decrease the TA contents in V. amurensis berries. Meanwhile, all NaHSO₃ treatments had higher SS, SS/TA, glucose, and sucrose than treatments with the same concentrations of INH. However, the arabinose contents in all the INH treatments were higher than those in NaHSO₃ treatments at the same concentrations. Compared with INH treatments, NaHSO₃ were better at increasing net photosythesis rate (Pn), Rubisco carboxylation efficiency (CE), intercellular CO₂ concentration (Ci) and decreasing photorespiration rate (Pr). However, the effects of NaHSO₃ and INH on fluorescent characteristics of V. amurensis leaves were not significant. The fact that maximal values for photochemical efficiency of photosystem II complex (PSII) in the dark (F_v/F_m) in this study were large indicate that both NaHSO₃ and INH had positive effects on chlorophyll fluorescence of V. amurensis leaves, which meant they had the ability to release surplus light energy and mitigate photoinhibition by inhibiting photorespiration at all three concentrations. Comprehensive analysis clearly indicates that NaHSO₃ had better effects on photorespiration inhibition and fluorescent characteristics, and improved photosynthesis and the quality of V. amurensis grape berries, especially at 250 mg L^-1.