作 者 ：鲁建荣1,2,3,李向义1,3*,薛 伟1,3,4,林丽莎1,3,李 磊1,2,3,张新林1,2
期 刊 ：西北植物学报 2013年 7期 页码：1427~1434
Keywords:desert plants, water stress, water status, photosystem Ⅱ,
摘 要 ：以塔克拉玛干南缘的优势物种疏叶骆驼刺(Alhagi sparsifolia)和引进种大果白刺(Nitraria roborowskii)的离体叶片为实验材料,比较了不同水分状况下水势、气孔导度和叶绿素荧光参数的变化特征。结果显示：(1)大果白刺在脱水胁迫初期气孔导度值（Gs）高达495.7 mmol·m-2·s-1,相对含水量（RWC）>96%时Gs降幅较小,维持较高气孔开度进行光合作用；骆驼刺气孔对脱水胁迫反应较灵敏,Gs值控制在180 mmol·m-2·s-1以内且Gs总体下降缓慢。（2）大果白刺在RWC>84%时水势高于骆驼刺并保持平稳下降,骆驼刺始终保持较缓慢下降趋势。（3）二者叶片气孔导度与水势绝对值均呈负指数回归关系,-2.2 Mpa为大果白刺水势临界点,未发现骆驼刺有明显临界点。（4）二者的叶绿素荧光参数在脱水胁迫下均表现为初始荧光F0显著上升,PSⅡ最大光化学效率Fv/Fm和潜在活性中心Fv/F0值下降；骆驼刺的单位反应中心捕获的能量（TRo/RC）和单位反应中心数目（RC/CSo）呈波动变化,大果白刺在RWC<78%时各项荧光比活性值急剧上升且荧光曲线转为平台型。研究表明,骆驼刺具有低水势忍耐脱水的抗旱方式,并且反应中心可能存在可逆失活和能量陷阱等方式响应水分胁迫,而大果白刺具有高水势延迟脱水特征,其水分胁迫极限阈值RWC为78%；骆驼刺作为当地的优势种对干旱具有较强的适应性和耐受性,而大果白刺并不适宜在长期干旱胁迫或者地下水位波动较大的地区进行引种推广。
Abstract:Samples of Alhagi sparsifolia and Nitraria roborowskii leaves were colleted on the south fringe of the Taklimakan desert.At different relative water contents (RWC),we investigated the characteristics of the water potential (ψw),stomatal conductance (Gs) and chlorophyll fluorescence parameters changes.The results indicated that:(1)Under the dehydration stress,the initial Gs value of N.roborowskii was high as 495.7 mmol·m-2·s-1 and decreased slowly when RWC above 96%;While A.sparsifolia’s stoma responded quickly to the dehydration stress,it could control the Gs value in 180 mmol·m-2·s-1 and had a generally slow decrease.(2)N.roborowskii’s initial water potential was higher than A.sparsifolia’s and could maintain some stability in extent,but when RWC below 84%,its ψw began to decrease strongly under the level of A.sparsifolia’s,which always maintained more slowly.(3)The two’s leaves Gs to absolute ψw showed negative exponential regression relationship and there was a critical point of ψw to Gs of N.roborowskii as -2.2 Mpa,but A.sparsifolia had no clear point.(4)On the natural dehydration,both two showed F0 rose significantly,Fv/Fm,Fv/F0 values decreased.N.roborowskii had more severe damage to reaction centers,but A.sparsifolia’s Fv/Fm value more than 0.1 until RWC was 55%,indicating it’s PSⅡ reaction centers itself was stable,meanwhile,its TRo/RC,RC/CSo values posed fluctuate and its RC/CSo changed insignificantly.N.roborowskii’s fluorescence specific activity values increased suddenly and the fluorescence curves distorted when RWC less than 78%.In summary,A.sparsifolia posed low water potential to tolerate dehydration and it may exist reaction centers lose activity reversible and energy trap to carry on heat dissipation and respond water stress,while N.roborowskii showed maintain high water potential to delay dehydration and its RWC point which stands for water stress utmost threshold was 78%.In all,A.sparsifolia as local dominant species have a better adaptability and tolerance and N.roborowskii is not suitable for the area to introduce and spread where or long term consistent drought or groundwater level fluctuates strongly exist.