华山新麦草光合特性对干旱胁迫的响应

以濒危植物华山新麦草为材料进行盆栽试验,设置3个水分梯度,研究生长指标、气体交换、叶绿素荧光参数、光合色素含量、光响应特征及丙二醛(MDA)含量.结果表明:随干旱胁迫的加剧,株高、叶宽和光合色素含量降低,根长和丙二醛(MDA)含量增加；水分胁迫导致净光合速率(PN)、气孔导度(gs)、蒸腾速率(E)、最大荧光(Fm)、光合电子传递速率(ETR)和光化学猝灭系数(qP)降低,胞间CO2浓度(Ci)、瞬时水分利用效率(WUE)、初始荧光(Fo)和非光化学淬灭系数(NPQ)升高；光系统Ⅱ最大光化学效率(Fv/Fm)不变；干旱胁迫下光响应曲线拟合结果显示,干旱胁迫造成最大光合速率和光能利用效率下降.综上表明,干旱对光系统Ⅱ的伤害是制约华山新麦草光合作用的主要原因.

Response of photosynthetic characteristics of Psathyrostachys huashanica Keng to drought stress

The response of photosynthetic characteristics in Psathyrostachys huashanica Keng was studied by measuring growth parameters, gas-exchange, photosynthetic pigment contents, modulated chlorophyll fluorescence and malonaldehyde (MDA) contents under 3 different water stresses in pots. The result exhibited that, when increasing water stress, plant height, the width of leaf and photosynthetic pigment contents decreased and root length and MDA contents enhanced. Water stress has induced the decreasing of net photosynthesis (PN), stomatal conductance (gs), ratio of transpiration (E), the maximum fluorescence (Fm), the electron transport rate (ETR) and photochemical quenching (qP) and an increase of ratio of intercellular CO2, intrinsic water use efficiency (WUE), the minimal fluorescence (Fo) and non-photochemical quenching (NPQ). The maximum quantum yield of photo-system II (PSII) (Fv/Fm) kept invariable under water stress. The fitted indexes from photo-response curves of Pn showed that drought has induced photosynthetic potential and light use efficiency. Summing up and obtains a conclusion, the injury of PSII induced by drought was main cause restraining factors of photosynthesis, we can study the endangered causes of Psathyrostachys hashanica Keng from the aspect.