倍增CO_2分压对水稻和矶子草冠层光合潜力的影响

Effects of double CO_2 partial pressure on the canopy potential photosynthesis of Oryza sativa and Leptochloa panicea.

倍增CO2 分压增高水稻的光饱和光合速率、表观量子产率和光能转换效率 ,而在倍增CO2 分压下矶子草的相关光合参数降低 ,既水稻对高CO2 分压表现为正响应 ,而矶子草在高CO2 下光合作用下调。在倍增CO2 分压下 ,水稻的Rubisco羧化速率和氧化速率均见增高 ,而矶子草在高CO2 分压下 ,Rubisco羧化速率降低 ,而氧化速率略见增高。倍增CO2 分压并不明显改变水稻的不包括光呼吸的CO2 补偿点Γ ,但矶子草Γ 略见增高。在高CO2 分压下可能改变矶子草Rubisco生化特性。倍增CO2 分压降低两种供试植物的光下呼吸速率。水稻在倍增CO2 分压下其Rubisco最大羧化速率 (Vcmax)和最大电子传递速率 (Jmax)分别增高 9 3%和 2 0 7% ,而矶子草在高CO2 分压下则分别降低 5 7%和 3%。在倍增CO2 分压下水稻的净光合量增高约 5 % ,而矶子草则降低 13% ,植物种的不同特性可能影响植物在倍增CO2 下的碳积累。随着全球气候变化和大气CO2 分压增高 ,将有利于发挥水稻高光合产率的优势 ,由于矶子草在高CO2 分压下碳积累减少 ,从而可能限制其生长。大气CO2

The light saturated rate of photosynthesis, apparent photosynthetic quantum yield and the efficiency of light energy conversion increased in leaves of O. sativa, exposed to double CO 2 partial pressure and the same parameters were decreased in leaves of L. panicea in comparison with that under ambient CO 2 partial pressure. The carboxylation rate and oxygenation rate of Rubisco increased simultaneously and the ratio between them did not change much in leaves of O. sativa. No significant change of CO\-2 compensation point in the absence of light respiration (Γ *) occurred in O. sativa and increasing Γ * was found in L. panicea. The result showed that the property of Rubisco could be modified in L. panicea exposed to double CO 2 partial pressure. The respiration rate in light decreased in both plants exposed to double CO 2 partial pressure maximurn carboxylation rate of rabisco. (Vcmax) and maximum rate of photo synthetic elactron transprt(Jmax) increased by 9.3% and 20.7% in O. sativa and decreased by 5 7% and 3% in L. panicea respectively as they were exposed to double CO 2 partial pressure. The daily canopy net photosynthesis increased by 5% in O. sativa and decreased by 13% in L. panicea when both were exposed to double CO 2 partial pressure. The results showed that the species characters influence carbon gained under higher CO 2 partial pressure. The advantage in higher production in O. sativa would be promoted as the global atmospheric CO 2 partial pressure would increase continuously, and the current ecological relationship between O. sativa and L. panicea be changed for the carbon assimilation in L. panicea decreased under double CO 2 partial pressure.