CO_2浓度升高对龙血树和春羽生长及光合生理的影响

Effect of Elevated CO_2 Concentration on the Growth and Photosynthetic Physiology of Dracaena angustifolia and Philodenron selloum

采用开顶式气室(OTC)控制模拟环境,研究了二氧化碳(CO2)浓度升高对龙血树和春羽叶片光合生理及叶绿素荧光参数的影响。结果表明:(1)随着CO2浓度增加,龙血树和春羽幼苗叶面积和株高均呈显著增加趋势。(2)龙血树和春羽幼苗叶片净光合速率随着CO2浓度的升高均呈先增加后降低的趋势,而同期蒸腾速率和气孔导度显著降低。(3)随着CO2浓度的增加,龙血树和春羽幼苗叶片最大光量子产量、实际光能转化效率均呈先升后降的趋势,而同期非光化学猝灭系数呈先降低后升高的趋势;光化学猝灭系数总体上也呈先升高后降低的趋势,但差异不显著。研究表明,一定时间的高浓度CO2处理提高了龙血树和春羽的净光合速率,促进了植物的生长,但随着处理时间的延长,这种促进作用逐渐降低进而消失,并以春羽幼苗表现得更突出;即高浓度CO2可能破坏了龙血树及春羽生长后期光系统Ⅱ反应中心结构,导致叶片光合能力降低。

To study the effects of elevated CO2 concentration （CO2） on the leaf photosynthesis and chlorophyll fluorescence parameters in Dracaena angustifolia and Philodenron selloum, we exposed the seedlings of D. angustifolia and P. sellourn to either ambient CO2 [-CK, （390= 30） /1tool tool-1] or elevated CO2 [TI , （780=30） /1tool tool ;T2, （1 560＋30） /μmol tool-l in an open top chamber. The results showed that ： （1） Leaf area and plant height of seedlings significantly raised with the increase of CO2 concentration. （2）Under the high CO2 concentration,the net photosynthetic rate （Pn） was higher earlier and lower later, but their stomatal conductance （Gs） and transpiration rate （Tr） significantly reduced. （3）The ratio of variable fluorescence to maximal fluorescence （Fv/Fm） and the actual photochemical efficiency （φeSll） tend to increased and then decreased with the CO2 concentration raised. Photochemical quenching coefficient （qe） also had the same trend,but the difference was not significant. On the contrary,non photochemical quenching coefficient （NPQ） tends to decrease earlier certain extent might be beneficial for increasing and increased later. The increasing C02 concentration in a net photosynthetic rate and the vegetative growth, but the promotion decreased slowly and then disappear if CO2 enrichment prolonged. The performance of P. selloum seedling was more outstanding. It suggested that the higher CO2 concentration could injure the structure o{ leaf photosystem 1I and consequently decreased the leaf photosynthetic capacity in the late growth phase of D. angusti folia and P. seHoum.