SEASONAL-CHANGES IN LEAF WATER POTENTIAL COMPONENTS IN 2 ALMOND CULTIVARS

Almond trees (Amygdalus communis L. cvs Garrigues and Ramillete) were grown in the field under non-irrigated conditions in Murcia, Spain. Se asonal variations in leaf water potential components were studied in 1 989. Predawn leaf water potential showed high values in both cultivars , due to the absence of soil water stress. Pressure-volume curve analy sis indicated that the leaf osmotic potential at full saturation (PSI( o)(sat)) for cv. Garrigues remained fairly constant throughout the sea son. Bulk modulus of elasticity (E) showed, in both cultivars, a tende ncy to decrease as the season progressed. E values were higher in Rami llete than in Garrigues. The relative water content at the turgor loss point (RWC(tlp)) seemed to be controlled by E values. The larger rela tive apoplastic water content (RWC(a)) found in Ramillete might have a llowed it to retain more water at low leaf water potentials than Garri gues. These facts would support the suggestion that Ramillete is a mor e drought-resistant cultivar than Garrigues.