Leaf thickness and turgor pressure in bean during plant desiccation

• Leaf thickness and turgor pressure were measured during forced plant desiccation.
• Leaf thickness followed closely the steep decline of the total water potential (Ψ).
• A link between leaf thickness and turgor pressure could not be verified.
• Leaf thickness appeared to decrease in discrete levels.

This study investigated a possible relationship between the relative change of leaf thickness and the relative degree of turgor pressure in leaf cells. Leaf thickness and turgor pressure were measured simultaneously during forced plant desiccation in bean plants. Although leaf thickness followed closely the steep decline of the total water potential (Ψ) during the desiccation process, no conclusive relationship could be observed between leaf thickness and the osmotic water potential (Ψs). Thus, a potential link between the relative change of leaf thickness and the relative degree of turgor pressure could not be verified under the experimental conditions. Earlier findings, that the relative change of leaf thickness is closely related to the relative change of the total water potential of leaf cells, are corroborated. Additional observations were: (i) a potential relationship between the relative change of leaf thickness during desiccation and the totally achieved leaf thickness, and (ii) the apparent decrease of leaf thickness during desiccation in discrete levels rather than a truly continuous decline.