[Effects of nitrate application on alleviating photosynthesis restriction of Cinnamomum burmannii leaves under elevated CO2 concentration and enhanced temperature].
In this study, potted C. burmannii saplings were cultured in a top-closed chamber with elevated CO2 (+ CO2, 731 micromol x mol(-1)) and ambient CO2(CO2, 365 micromol x mol(-1)), and at diurnal temperature (day/night) 25/23 degrees C and 32/25 degrees C, respectively. The gas exchange, calculated photosynthesis parameter, Rubisco content, and activated state of Rubisco were examined. The results showed that under + CO2 and at 25/23 degrees C, the mean photosynthetic rate (Pnsat) of sapling leaves was 5.1% higher than that under + CO2 and at 32/25 degrees C. Temperature enhancement declined Pnsat, while nitrate addition increased it. Under + CO2, saplings had lower V(cmax) and J(max) at 32/25 degrees C than at 25/23 degrees C. Temperature enhancement under + CO2 also declined V(cmax) and J(max). Under + CO2, lower photorespiration rate (Rp) occurred in leaves, but temperature enhancement could increase Rp. Under + CO2, Rubisco content (NR) and its active site per unit leaf area (M) decreased as diurnal temperature changed from 25/23 degrees C to 32/25 degrees C. Meanwhile, nitrate addition could increase NR and M. It may be suggested that nitrate addition could alleviate the restriction of photosynthesis under elevated CO2 concentration and enhanced temperature.
Sun
Guchou
G
South China Institute of Botany, Chinese Academy of Sciences, Guangzhou 510650, China.
Zhao
Ping
P
Rao
Xingquan
X
Cai
Xi'an
X
Zheng
Xiaoping
X
D002245:Carbon Dioxide / Q000032:analysis*; D027424:Cinnamomum / Q000502:physiology*; D009566:Nitrates / Q000737:chemistry*; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism*; D013696:Temperature
D009566:Nitrates; D002245:Carbon Dioxide