Department of Horticulture, Cook College, Rutgers-The State University of New Jersey, New Brunswick, New Jersey 08903.
Plant Physiol. 1990 Mar;92(3):733-9. doi: 10.1104/pp.92.3.733.
Studies were undertaken to examine the relationship between water deficit effects on photosynthesis and the extent of protoplast volume reduction which occurs in leaves at low water potential (Psi(w)). This relationship was monitored in two cultivars (;Condor' and ;Capelle Desprez') of cultivated wheat (Triticum aestivum) that differed in sensitivity to drought, and in a wild relative of cultivated wheat (Triticum kotschyi) that has been previously found to be ;drought resistant.' When subjected to periods of water stress, Condor and T. kotschyi plants underwent osmotic adjustment; Capelle plants did not. Photosynthetic capacity was maintained to different extents in the three genotypes as leaf Psi(w) declined during stress; Capelle plants were most severely affected. Calculations of internal leaf [CO(2)] and stomatal conductance from gas exchange measurements indicated that differences in photosynthetic inhibition at low Psi(w) among the genotypes were primarily due to nonstomatal effects. The extent of protoplast volume reduction that occurred in leaves at low Psi(w) was also found to be different in the three genotypes; maintenance of protoplast volume and photosynthetic capacity in stressed plants of the genotypes appeared to be correlated. When the extent of water stress-induced inhibition of photosynthesis was plotted as a function of declining protoplast volume, this relationship appeared identical for the three genotypes. It was concluded that there is a correlative association between protoplast volume and photosynthetic capacity in leaves of wheat plants subjected to periods of water stress.
进行了研究以检查水分亏缺对光合作用的影响与在低水势（Psi(w)）下叶片中质体体积减小的程度之间的关系。这种关系在两个栽培小麦（Triticum aestivum）品种（“Condor'”和“Capelle Desprez”）中进行了监测，这两个品种对干旱的敏感性不同，并且在先前发现具有“抗旱性”的栽培小麦的野生近缘种（Triticum kotschyi）中进行了监测。当受到水分胁迫时，Condor 和 T. kotschyi 植物经历了渗透调节；Capelle 植物没有。随着胁迫过程中叶片 Psi(w)的下降，三种基因型的光合作用能力在不同程度上得以维持；Capelle 植物受到的影响最为严重。从气体交换测量中计算出的内部叶片 [CO(2)] 和气孔导度表明，在低 Psi(w)下三种基因型之间光合作用抑制的差异主要是由于非气孔效应所致。在三种基因型中，在低 Psi(w)下叶片中发生的质体体积减小的程度也不同；在受胁迫的植物中保持质体体积和光合作用能力似乎是相关的。当将水分胁迫诱导的光合作用抑制程度绘制为质体体积减小的函数时，三种基因型之间的关系似乎相同。得出的结论是，在受到水分胁迫的小麦叶片中，质体体积和光合作用能力之间存在相关关系。
