Nonstomatal limitations are responsible for drought-induced photosynthetic inhibition in four C4 grasses
Nonstomatal limitations are responsible for drought-induced photosynthetic inhibition in four C4 grasses
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DOI：
10.1046/j.1469-8137.2003.00835.x
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发表时间：
2003-09-01
期刊：
影响因子：
9.4
通讯作者：
Lawlor, DW
中科院分区：
文献类型：
--
作者：
Ghannoum, O;Conroy, JP;Lawlor, DW
以四种热带C-4禾草（Panicum coloratum, Bothriochloa bladhii， Cenchrus ciliaris和Astrebla lappacea）为研究对象，研究了水分胁迫下气孔和非气孔因子对光合抑制的影响。在水分充足的土壤中种植植株，测定土壤干燥对叶片气体交换、叶绿素a荧光和水分关系的影响。叶片水势（Psi）和相对含水量（RWC）在干燥周期内分别从-0.4 MPa和-2.8 MPa下降到100-40%。4种禾草的CO2同化速率(A)和PSII的量子产率（Phi(PSII)）随RWC的降低而迅速下降。在干燥周期的任何阶段，高CO2浓度（2500 μ l(-1)）对A和Phi（PSII）没有影响。电子传递能力和暗呼吸速率不受干旱影响。当叶片RWC低于70%时，花楸和毛楸的CO2补偿浓度急剧上升。在水分胁迫下，5%的CO2浓度并不能阻止花楸O-2演化速率的下降。因此，水分胁迫对4种C-4禾本科植物光合作用的抑制主要依赖于生物化学限制。
Here, the contribution of stomatal and nonstomatal factors to photosynthetic inhibition under water stress in four tropical C-4 grasses was investigated (Panicum coloratum, Bothriochloa bladhii, Cenchrus ciliaris and Astrebla lappacea ).Plants were grown in well watered soil, and then the effects of soil drying were measured on leaf gas exchange, chlorophyll a fluorescence and water relations.During the drying cycle, leaf water potential (Psi(leaf)) and relative water content (RWC) decreased from c. -0.4 to -2.8 MPa and 100-40%, respectively. The CO2 assimilation rates (A) and quantum yield of PSII (Phi(PSII)) of all four grasses decreased rapidly with declining RWC. High CO2 concentration (2500 mul l(-1)) had no effect on A or Phi(PSII) at any stage of the drying cycle. Electron transport capacity and dark respiration rates were unaltered by drought. The CO2 compensation concentrations of P. coloratum and C. ciliaris rose sharply when leaf RWC fell below 70%. In P. coloratum, 5% CO2 did not prevent the decline of O-2 evolution rates under water stress.We conclude that inhibition of photosynthesis in the four C-4 grasses under water stress is dependent mainly on biochemical limitations.