Osmotic adjustment in sessile oak seedlings in response to drought

Three-year-old sessile oak seedlings were submitted to drought developed at two different rates (0.050 and 0.013 MPa . day(-1)). Drought was controlled by combining levels of irrigation and grass competition. At the end of summer, predawn leaf water potential reached values of -2.3 and -0.8 M Pa in the rapid and slow rates of drought development, respectively, and leaf osmotic potential at full turgor reached values of -2.0 and -1.5 MPa, for the same treatments. For both treatments, leaf water potential and leaf osmotic potential were linearly and positively correlated. The rapid rate of drought development resulted in a greater degree of osmotic adjustment (0.45 versus 0.34 MPa . MPa-1).