Obtaining Salt (NACL) Tolerant Olive Plants: 1) Sorne Physiological and Anatornical Characteristics of Olive Plants Growing in Harsh Saline Zones

With the final aim of obtaining saIt tolerant olive plants, olive cvs. growing in the olive Germplasm Bank (World Collection) of Córdoba (Spain) (WC-CO) and plants growing in three harsh saline zones, each divided into two subzones, were selected. The zones and subzones were: "Odiel" River Marsh (Huelva) with the subzones "Rabo conejo" (O-RC) y "Acebuchal" (O-AC); "Doñana" National Park (Huelva) with the subzones "Zainao" (D-ZA) and "Velázquez" (D-VE) and "Bahia de Cádiz" Natural Park with the subzones "S. Fernando" (C-SF) and "Puerto Real" (C-PR). There were differences between the leaf mineral composition of the cvs. growing in WC-CO, and plants growing in the different saline zones, that showed higher contents of Na and CI (influence of NaCl in soil and air) and gene rally lower levels of N, K, and Ca. Among oligoelements, saline zone plants presented higher Fe and lower Mn and Cu contents. AnatomÍcal observations revealed high variability in the leaves of the plants from the high saline zones, which in many cases were thinner than the WC-CO cv.s, largeIy due to reduced spongy mesophyll. A slight relationship was seen between leaf Na and CI content and total leaf and palisade parenchyma thickness for the leaves from saline zones. INTRODUCTION Soil salinity is a serious problem in sorne arid afeas of the Mediterranean basin, where plants are subjected to high temperature regimes and water deficits. In these areas, the use of saline waters sometimes represents the only possibility for irrigation. However salt stress conditions affect growth, production, leaf drop, etc. of cultivated trees. Noncultivated or marginal olive plants, living in harsh saline conditions could have higher resistance to salt stress. These genotypes, with promising potential genetic value, are on rhe pathway of regression, or are even endangered plants. Both the selection and characterisation of clones with a superior resistance to limiting conditions and the rescuing of genotypes of high ecological and genetic value could facilitate preservation of the traditionallandscape and improve agricultural utilisation. The presence of NaCI in the medium changes the mineral composition of olive plants mainly by increasing Na and Cl and decreasing K and Ca contents (Bartolini et al., 1991). Growth under saline conditions may also affect both anatomical and morphological aspects of lea ves in the olive as well as other glycophytic species (Gucci and Tattíni, 1997). Both leaf nutritional content and anatomical characteristics, together with olive plant behaviour, could be linked with the genetic capacity of the plants to adapt to