Abstract: Abstract: The apparent quantum yield (AQY) and photosystem Ò photochemical efficiency ( Fv/ Fm) in ginger ( Zingiber off icinale Rosc. ) leaves decreased significantly at clear midday, which indicated that obvious
photoinhibition occurred, eg. , the AQY of 80%, 60% , 40% relative soil water contents was 0. 0312, 0. 0296, 0. 0218 at 7: 00, but 0. 0261, 0. 0186, 0. 0108 at 13: 00, and the Fv/ Fm was 0. 788, 0. 762, 0. 752 at 7: 00, but 0. 728, 0. 682, 0. 601 at 13: 00, respectively. The stress condition, such as drought, high tem2 perature and strong light enhanced the photoinhibition considerably. When ginger leaves treated at 35 e, 1 200 Lmol#m- 2#s- 1 PFD, the Fv/ Fm was descended 12. 5% in an hour, but no changes at 25 e , dark in 6 hours. Decrease of photosynthesis and increased ratio of photorespiration to photosynthesis were observed in water stress condition. The de2epoxidation extent of xanthephyll cycle was accelerated in ginger leaves subjected towater stress. The data presented in this paper indicated that photorespiration and xanthophylls cycle were important
photoprotection mechanisms that effectively dissipate the excess light energy in ginger leaves.

Key words: Ginger, Photoinhibition, Photorespiration, Xanthophyll cycle