Photosynthesis and free radical yield of Litchi chinensis leaves under increased CO2 partial pressure in atmosphere
空气CO2增高条件下荔枝叶片光合作用和超氧自由基产率

The maximum photosynthetic rate of litchi saplings leaves grown under a CO2 partial pressure of 77 +/- 5 Pa was 23% lower than that of 39.3 Pa, and slight decreases in respiration rate in light and CO2 compensation point excluding of respiration in light were observed. The maximum rates of carboxylation (Vcmax) and photosynthetic electron transport (Jmax) were decreased in saplings grown under 77 +/- 5 Pa CO2 partial pressure. It may suggest that there was a lower energy level of photosystem I(PSI) in the saplings leaves under 77 +/- 5 Pa CO2 partial pressure, and free radical yield decreased by 39% in the saplings under 77 +/- 5 Pa CO2, as comparied with that under atmospheric CO2. The percentage of infection by Peronophythora litchi increased from 1.8% under atmospheric CO2 to 9.5% under enriched CO2. It may mean that the decreasing photosynthetic and respiration metabolism would make it lower the production of O2-., and leaves were infected by P. litchi more easily. The controlling of the popularization of P. litchi for litchi plantation must be paid wide attention, as air CO2 partial pressure will increase continuously.