Comparative Leaf Anatomy and Pressure-Volume Analysis in Plants of Ipomoeapes-caprae Experimenting Saline and/or Drought Stress

摘要

Ipomoea pes-caprae is a vine common in tropical and subtropical coasts. This species appears to be more susceptible to drought as compared with saline stress and when both stresses are combined, the water and carbon balance may be enhanced compared with the two stresses applied independently. In this study, leaf anatomy and parameters obtained by P-V analysis were measured in J. pes-caprae experimenting saline and/or water stress. NaCl and PEG were used to induce iso-osmotic pressures in the soil solution (psi_(sol)) to -5 and -10 bar and both osmotica were combined to apply simultaneous saline and water stress (S+W) for a total reduction in psi_(sol) of -5 bar. Saline and/or water stress increased the lamina thickness and cell size but the effect was higher under high saline stress. Osmotic potential at full (psi_(phi)) and at zero (psi_phi)) turgor were significantly lower at high salinity and S+W stress, compared with the other treatments. Osmotic adjustment resulting from net solute accumulation explains 85-98% of the total change in psi_(phi)v. The contribution of dehydration to changes in was apparent only under high water stress. Single stress had no significant effect on the modulus of elasticity (e) and apoplastic water fraction. However,plants growing under S+W showed the lowest values of e. Changes in and ? affected the relative ability of plants subjected to S+W treatment to maintain high turgor pressure at lower relative water content and confirm that the ability of J. pes-caprae togrow under lower psi_(sol) may be increased if experiments both stresses simultaneously.