干旱胁迫和CO_2浓度升高条件下白羊草的光合特征

Photosynthetic characteristics of Bothriochloa ischaemum under drought stress and elevated CO_2 concentration

采用盆栽控制试验,研究了黄土丘陵区乡土种白羊草在不同水分水平(80%FC和40%FC)和CO2浓度(375和750μmol·m-2·s-1)处理下的光合生理变化特征.结果表明:干旱胁迫使白羊草的最大净光合速率(Pnmax)、表观量子效率(AQE)、气孔导度(gs)、蒸腾速率(Tr)、最大光化学效率(Fv/Fm)、潜在光化学效率(Fv/Fo)和光合色素含量降低,丙二醛(MDA)和脯氨酸(Pro)含量升高.水分充足条件下,与正常大气CO2浓度相比,大气CO2浓度倍增下白羊草的Pnmax、MDA和Pro含量无显著差异.干旱胁迫下,CO2浓度升高提高了白羊草的最大荧光(Fm)、Fv/Fm、Fv/Fo、叶绿素含量和AQE,Pnmax比正常CO2浓度下高23.3%,差异达到显著水平,而MDA和Pro含量均显著降低.CO2浓度升高对干旱胁迫引起的白羊草光合能力下降有一定的补偿作用,减轻了干旱胁迫对白羊草的伤害.

A pot experiment was conducted to study the variations of the photo-physiological charac- teristics of native bluestem （Bothriochloa ischaemum） in loess hilly-gully region under different soil moisture condition （80% and 40% field capacity） and different atmospheric CO2 concentration （375 μmol. m-2 . s-1 and 750 μmol. m-2 . s-1 ）. The results showed that drought stress de- creased the maximum photosynthetic rate （Pnmax）, apparent quantum efficiency （AQE）, stomatal conductance （gs）, transpiration rate （ T^T ）, maximum photochemical efficiency （ Fv/Fm ）, potential photochemical efficiency （Fv/Fo ）, and photosynthetic pigments contents, and increased the malon- dialdehyde （MDA） and proline （Pro） contents. Under sufficient moisture condition, elevated CO2 concentration didn＇t change the P_n max and the MDA and Pro contents significantly; under drought ambient CO2 concentration. All the results suggested that elevated CO2 concentration had definite compensation effect on the photosynthetic reduction of B. ischaemum induced by drought stress, and alleviated the damage of drought stress on B. ischaemum.