Field water relations ofCapparis spinosaL.

This paper describes the water relations in expanded leaves ofCapparis spinosaunder natural conditions during summer. Predawn water potential was sustained above −2·3 MPa. The lowering of solute potential may not be attributed to osmotic adjustment, since concentrations of proline and sugars were reduced. Stomatal conductance of leaf adaxial surface was higher than that of the abaxial. At noon, stomatal conductance up to 100 mmol m−2s−1was measured concomitantly with turgor loss point. The results indicate thatC. spinosais a stenohydric plant, which during the summer is largely free of competition for water with other species of the Mediterranean region.