Istituto Sperimentale per la Cerealicoltura, S.S. 16 Km. 675, 71100 Foggia, Italy.
Plant Physiol. 1992 Mar;98(3):908-12. doi: 10.1104/pp.98.3.908.
To study drought stress effects on bound water, adsorption isotherms and pressure-volume curves were constructed for two durum wheat (Triticum durum Desf.) cultivars: Capeiti 8 (drought tolerant) and Creso (drought sensitive). Plants were grown under well-watered and water-stressed conditions in a controlled environment. Differential enthalpy (DeltaH) was calculated through van't Hoff analysis of adsorption isotherms at 5 and 20 degrees C, which allowed us to determine the strength of water binding. DeltaH reached the most negative values at approximately 0.06 gram H(2)O/gram dry weight and then increased rapidly for well-watered plants (until 0.10 gram H(2)O/gram dry weight) or more slowly for drought-stressed plants (until 0.15-0.20 gram H(2)O/gram dry weight). Bound water values from pressure-volume curves were greater for water-stressed (0.17 gram H(2)O/gram dry weight) than for well-watered plants (0.09 gram H(2)O/gram dry weight). They may be estimates of leaf moisture content where DeltaH reaches the less negative values and hence some free water appears. With respect to the well-watered plants, tightly bound water tended to be less bound during drought, and more free water was observed in cv Creso compared to cv Capeiti 8 at moisture contents >0.10 gram H(2)O/gram dry weight.
为了研究干旱胁迫对束缚水的影响，我们为两个硬质小麦（Triticum durum Desf.）品种：Capeiti 8（耐旱）和 Creso（耐旱）构建了吸附等温线和压力-体积曲线。在受控环境下，植物在充分浇水和水分胁迫条件下生长。通过 van't Hoff 分析在 5 和 20°C 下的吸附等温线计算出微分焓（DeltaH），这使我们能够确定水结合的强度。DeltaH 在大约 0.06 克 H₂O/克干重时达到最负的值，然后对于充分浇水的植物迅速增加（直到 0.10 克 H₂O/克干重），或者对于干旱胁迫的植物缓慢增加（直到 0.15-0.20 克 H₂O/克干重）。压力-体积曲线得出的束缚水值对于水分胁迫的植物（0.17 克 H₂O/克干重）大于充分浇水的植物（0.09 克 H₂O/克干重）。它们可能是叶片含水量的估计值，在这个值处 DeltaH 达到较小的负值，因此出现了一些自由水。就充分浇水的植物而言，在干旱期间，紧密束缚的水往往束缚得更少，在水分含量大于 0.10 克 H₂O/克干重时，与 Capeiti 8 相比，Creso 品种中观察到更多的自由水。
