Suárez N, Sobrado M A, Medina E
Laboratorio de Biología Ambiental de Plantas, Universidad Simón Bolívar, Caracas, Venezuela e-mail:
Laboratorio de Ecofisiología Vegetal, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela , , , , , , VE.
Oecologia. 1998 Apr;114(3):299-304. doi: 10.1007/s004420050451.
Physiological traits involved in leaf water relations were evaluated in Avicennia germinans (L.) L. seedlings growing at different salinities in the field. Analysis of pressure-volume (P-V) curves and sap osmometry were combined to evaluate osmotic adjustment and cell elasticity, and the contribution of accumulated inorganic ions to osmotic potential was estimated. Seedlings growing in soils with interstitial water salinity above that of normal sea water showed a modification of the relationship between water potential and relative water content. Thus, their leaf osmotic potential at maximum turgor (Ψ) and at zero turgor (Ψ) was 1.41 and 1.82 MPa lower respectively, than that of the seedlings from the low salinity site. Volumetric moduli of elasticity () were between 17 and 23 MPa. Thus, ɛ was about 6 MPa lower in high-salinity plants indicating that their cells were slightly more elastic. Ionic concentration analysis showed that Σ [anions] and Σ [cations] were higher in the high-salinity site (22-35%) while the water content per unit dry mass was only 12-17% lower. Reduction in water content was insufficient to explain the increase in ion concentration. Ion concentration explained 73 and 66% of the osmotic potential estimated by P-V curves for leaves from low- and high-salinity sites, respectively. In conclusion, this study provided evidence that leaves of A. germinans seedlings adapt to hypersaline soils by increasing solute concentration by 52% and cell elasticity by 26%. Both processes allow leaf water uptake and turgor maintenance over a large range of soil water potential.
对生长在野外不同盐度环境下的白骨壤（Avicennia germinans (L.) L.）幼苗的叶片水分关系所涉及的生理特性进行了评估。结合压力 - 容积（P - V）曲线分析和汁液渗透压测定来评估渗透调节和细胞弹性，并估算了积累的无机离子对渗透势的贡献。生长在间隙水盐度高于正常海水的土壤中的幼苗，其水势与相对含水量之间的关系发生了改变。因此，它们在最大膨压时（Ψ）和零膨压时（Ψ）的叶片渗透势分别比低盐度位点的幼苗低1.41 MPa和1.82 MPa。体积弹性模量（）在17至23 MPa之间。因此，高盐度植物的ɛ约低6 MPa，表明其细胞弹性略高。离子浓度分析表明，高盐度位点的Σ[阴离子]和Σ[阳离子]更高（22 - 35%），而单位干质量的含水量仅低12 - 17%。含水量的降低不足以解释离子浓度的增加。离子浓度分别解释了低盐度和高盐度位点叶片通过P - V曲线估算的渗透势的73%和66%。总之，本研究提供了证据表明，白骨壤幼苗的叶片通过将溶质浓度提高52%和细胞弹性提高26%来适应高盐土壤。这两个过程使得叶片能够在较大范围的土壤水势下吸收水分并维持膨压。
