Water relations of winter wheat. 3. Components of leaf water potential and the soil-plant water potential gradient
Wallace, J.S.; Clark, J.A.; McGowan, M.
Journal of Agricultural Science, UK 100(3): 581-589
Diurnal and seasonal changes in the total, osmotic and turgor potentials of winter wheat leaves were compared in 2 seasons of mild and severe soil water stress. Gradients of total water potential in the soil-plant system are also presented. In both seasons the total water potential of the leaves decreased in parallel with the soil water potential, concurrently leaf osmotic potential also decreased sufficiently to maintain positive leaf turgor potential. Eventually, under severe water stress, soil water potential approached -1.5 MPa and leaf turgor potential tended to zero during the middle of the day. The potential drop across the soil-root system was twice that along the stem.