【摘要】 在1—30％O₂ 浓度范围内,经无CO₂ 2000 μEm^-2s^-1处理 3小时后光抑光合程度随处理期间O₂ 浓度的增加而被缓解:甚至完全解除。当 O₂ 浓度高于 30％以上时,出现光抑光合加重的现象。在可诱导光抑光合产生的条件下,处理3小时的过程中,光呼吸只能维持40—60分钟。在较长时间的光抑光合处理条件下,光抑光合的缓解（光合能力的维持和恢复）与Mehler反应和SOD活性有较大的关系.更多还原

【Abstract】 The role of O2 in photoinhibition of photosynthesis in rice was investigated. When rice leaves were exposed to light and pure N2, their capacity of photosynthesis was drastically decreased, whereas less photoinhibition was observed in the presence of low partial pressures (1-2%) of O2. With O2 concentration increasing from 1% to 30% under CO2-free condition, photoinhibition was significantly or even totally prevented, but it was strongly promoted at O2 concentrations over 30%. Detectable photorespiratory rate could remain only 40-60 minutes during 3 hours of hhotoinhibitory treatment. These results indicate that photorespiration could only play a minor role in preventing hotoinhibition, and Mehler reaction may play an important role in dissipating excess energy. Reactive oxygen formed in Mehler reaction can be scavenged by the enzyme system superoxide dismutase, SOD which is present in chloroplast. Addition of diethyldithiocarbamate, DDTC or methyl vjologen,MV to rice leaves induces severe photoinhibition, even photobleaching by accum-lation of superoxide. Differences in susceptibility to photoinhibition of photosynthesis were observed among cultivars whose SOD activity were significantly different.It is concluded that O2 as a protectant may cause photoinhibition by toxic effect of reactive O2 when reactive O2 production exceeds capacity of scavenging system. SOD may play an important role in protecting photosynthetic apparatus from photooxidative damage.更多还原