SEASONAL PATTERNS OF WATER RELATIONSHIPS, PHOTOSYNTHETIC PIGMENTS ANDMORPHOLOGY OF ACTINIDIA-DELICIOSA PLANTS OF THE HAYWARD AND TOMURI CULTIVARS

Plant water relationships, photosynthetic pigments, osmotic solutes an d several morphological parameters were measured on leaves of 6-yr-old pistillate (Hayward) and 6-yr-old staminate (Tomuri) cultivars of kiw ifruit grown under Mediterranean climate conditions, in order to evalu ate physiological differences between them, and whether a good discrim inatory parameter can be obtained between rooted cuttings. The stamina te cultivar had higher leaf turgor and losses turgor at lower leaf-wat er potential than the pistillate cultivar. This was related to the low er osmotic potential at full turgor in Tomuri compared with Hayward, t ogether with the elastic properties of leaf tissue. Seasonal patterns of water potential components, cuticular water loss, proline, soluble sugars, photosynthetic pigments, cutin, turgid weight/dry weight ratio and specific leaf weight were all similar in both cultivars, whereas the hemicellulose/cellulose ratio differed. Thus, leaf-tissue elastici ty is important in determining the drought-resistance strategy of both cultivars, and the chemical composition of the cell walls, which is s trongly related to tissue elasticity, could provide a good discriminat ory parameter.