Albert Katz International School of Desert Studies, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Negev, Israel.
Physiol Plant. 2013 Apr;147(4):443-52. doi: 10.1111/j.1399-3054.2012.01671.x. Epub 2012 Sep 13.
Drought stress is known to limit photosynthesis rates and to inflict photo-oxidative damage in grapevines. Grapevines, which are considered drought-tolerant plants, are characterized by diverse hydraulic and photosynthetic behaviors, depending on the cultivar. This research compared the photosynthesis and the photorespiration of Cabernet Sauvignon (Cs) (isohydric) and Shiraz (anisohydric) in an attempt to acquire a wider perspective on the iso/anisohydric phenomenon and its implications. Shiraz and Cs were subjected to terminal drought in the greenhouse. Soil water content (θ), leaf water potential (Ψl ) and stomata conductance (gs ) were measured to determine the cultivars' hydraulic behavior. Gas exchange and fluorometry measurements were taken at 21 and 2% O2 to acquire photosynthesis and photorespiration characteristics. Cs was found to behave in a near isohydric manner whereas Shiraz behaved in a near anisohydric manner. Compared to Shiraz, the reduced stomata conductance values of Cs were accompanied by higher water use efficiency and photorespiration rates, as well as photosystem II photochemical potential (Fv /Fm ). As compared with Shiraz, Cs compensated for lower stomata conductance by higher photosynthesis and photorespiration. These two processes contributed to higher electron flow rates that might have a role in photoinhibition avoidance, which was observed in the stability of Fv /Fm under drought stress.
干旱胁迫已知会限制葡萄光合作用速率，并对其造成光氧化损伤。葡萄被认为是耐旱植物，具有不同的水力和光合行为，这取决于品种。本研究比较了赤霞珠（Cs）（等水合型）和设拉子（Shiraz）（非等水合型）的光合作用和光呼吸，试图更全面地了解等/非等水合现象及其意义。Shiraz 和 Cs 在温室中进行了末端干旱处理。测量土壤水分含量（θ）、叶片水势（Ψl）和气孔导度（gs）来确定品种的水力行为。在 21 和 2%O2 下进行气体交换和荧光测量，以获取光合作用和光呼吸特性。结果发现，Cs 表现出近等水合的行为，而 Shiraz 表现出近非等水合的行为。与 Shiraz 相比，Cs 的气孔导度值降低伴随着更高的水分利用效率和光呼吸速率，以及光合系统 II 光化学潜力（Fv/Fm）。与 Shiraz 相比，Cs 通过更高的光合作用和光呼吸来补偿较低的气孔导度。这两个过程有助于更高的电子流速率，这可能在避免光抑制方面发挥作用，这在干旱胁迫下 Fv/Fm 的稳定性中得到了观察。
