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以两个不同生态型的柳枝稷(Panicum virgatum)Alamo(低地型)和Cave-in-Rock(高地型)为试验材料,研究在0、50、100和150mmol·L~(-1) NaCl浓度下,分别添加0、0.5、1.0和2.0mmol·L~(-1)的外源硅(Na_2SiO_3·9H_2O)对其叶片光合色素含量及光合气体交换参数的影响。结果表明,Alamo叶片的叶绿素a、叶绿素b以及叶绿素a+b的含量均随着NaCl浓度的升高呈现降低趋势,但是Cave-in-Rock的变化趋势则相反。在无外源Si处理下,Alamo叶片净光合速率(Pn)和气孔导度(Gs)在50mmol·L~(-1) NaCl浓度下升高,100和150mmol·L~(-1)下降低;Cave-in-Rock的Pn、Gs和胞间CO_2浓度(Ci)随着NaCl浓度的增加逐渐降低。盐胁迫下,适当浓度外源硅(Si)的添加对Alamo和Cave-inRock叶绿素a、叶绿素a+b和叶绿素b、类胡萝卜素含量的提高具有积极的作用。外源Si的添加同样提高了盐胁迫下Pn、Gs和Ci等参数。本研究中,1~2mmol·L~(-1) Na_2SiO_3·9H_2O对盐胁迫下柳枝稷叶片光合色素及光合气体交换的促进作用较明显。
Panicum virgatum, Alamo and Cave-in-Rock were used as materials to study the effects of NaCl concentration at 0, 50, 100 and 150 mmol·L -1 NaCl concentrations The effects of exogenous silicon (Na_2SiO_3 · 9H_2O) (0, 0.5, 1.0 and 2.0 mmol·L -1) on photosynthetic pigment content and photosynthetic gas exchange parameters were studied. The results showed that the content of chlorophyll a, chlorophyll b and chlorophyll a + b in Alamo leaves tended to decrease with the increase of NaCl concentration, but the trend of Cave-in-Rock was opposite. The net photosynthetic rate (Pn) and stomatal conductance (Gs) of Alamo leaves increased at 50 mmol·L -1 NaCl concentration and decreased at 100 and 150 mmol·L -1 under exogenous Si treatment ; Pn, Gs and intercellular CO2 concentration (Ci) in Cave-in-Rock decreased with the increase of NaCl concentration. Under salt stress, addition of exogenous silicon (Si) at appropriate concentration had a positive effect on the increase of chlorophyll a, chlorophyll a + b, chlorophyll b and carotenoid content in Alamo and Cave-inRock. The addition of exogenous Si also increased the Pn, Gs and Ci parameters under salt stress. In this study, 1 ~ 2mmol·L -1 Na_2SiO_3 · 9H_2O promoted the photosynthetic pigment and photosynthetic gas exchange of switchgrass leaves under salt stress.