Abstract:

The stolons with and without adventitious roots of Sabina vulgaris were grown under controlled conditions of the pF 3.0 and pF 2.3 treatments by using PEG (polyethylene glycol) in their culture solutions. Diurnal changes of transpiration rate, stomatal conductance and water potential were measured. Leaf water relations were analyzed by Pressure-Volume curve. The results showed that: branches growing on the top part of stolons increased the ability of water absorption by lowering minimum potential under water stress. On the other hand, the constant leaf water potential of branches growing on the base part of stolons was maintained by controlling the transpiration under water stress. The stolon branches with adventitious roots uptake by decreasing water potential at turgor loss point (ψ^tlp_w) and osmotic potential at full turgidity (ψ^sat_s ). Moreover，the rapid response of stomata avoided excessive loss of water under stress. There was high bulk modulus of elasticity (ε) of its cell wall. The stolon branches without adventitious roots showed the lower ability of water absorption under water stress conditions, but they were able to tolerate water stress with their soft cell wall which could make them to maintain a constant turgor pressure under severe water loss conditions.

Key words: water stress, Sabina vulgaris, stolon, adventitious root water potential