拉瑞尔Larrea tridentata光合特性对CO2摩尔分数和干旱的响应

利用Li-6400光合测定系统测定拉瑞尔L.tridentata的光合生理特性及其对CO2摩尔分数升高和干旱的响应。结果表明：土壤水势在-0.884 5 MPa以上,L.tridentata的光合器没有任何损害,抵御干旱的能力很强;适当的增加CO2摩尔分数有利于提高光饱和点、光量子利用效率和最大净光合速率,且CO2摩尔分数升高的正效应要大于土壤水分胁迫的负效应,因而在一定程度上CO2摩尔分数的增加,提高了L.tridentata的抗旱能力;随着光合有效辐射的增强和CO2摩尔分数的升高,叶片净光合速率、CO2饱和点和羧化速率都有增大趋势,叶片对高摩尔分数CO2利用效率提高;不同土壤水分条件下,叶片气孔导度和蒸腾速率都随着CO2摩尔分数的升高而降低,水分利用效率随着CO2摩尔分数的升高而升高;既能饱和叶片的RubisCO,又不至于造成气孔大量关闭的CO2摩尔分数在700~800μmol.mol-1左右,说明目前的CO2摩尔分数还不足以饱和拉瑞尔的RubisCO酶。未来CO2摩尔分数升高,将对拉瑞尔的光合作用有所促进,并可能提高拉瑞尔对干旱的适应能力。

Phtotsynthetic physiological Response of Larrea tridentata due to the increase of CO2 concentration and drought

Li-6400 portable photosynthesis system was used to measure the photosynthetic physiological responses of larrea triden-tata to the increase of CO2 concentration and drought.The results showed that： Water stress had little influence on the leaf’s actinic process.Photosynthetic apparatus were not harmed by drought when the soil water potential was above-0.884 5 MPa.The light satu-ration point,the photosynthetic rate and the apparent photon utilization efficiency increased as the CO2 concentration increased.The positive effect of CO2 concentration increased is bigger than the negative effect from the drought,so the drought resistance ability of L.tridentata was raised to a certain extent by the CO2 concentration increase.The CO2 concentration saturation point（CSP） increased with the PARs and CO2 concentration increase.This indicated that the CO2 utilization efficiency increased.The stomatal conductance and transpiration decreased while WUE increased with the increase in CO2 concentration.The CO2 concentration which saturated leaf RubisCO while cause stoma closed was 700-800 μmol.mol-1.The current CO2 concentration has not saturated the RubisCO of L.tridentata.The CO2 concentration increased in the future will promote the photosynthesis of L.tridentata,and may increase the drought resistance ability of L.tridentata.