Morphological and Physiological Responses of Two Olive (Olea europea L.) Cultivars Saplings to NaCl Salinity Stress

Salinity is a major environmental stress that limits plant growth and productivity in Iran. Olive (Olea europea L.) is one of the most valuable and widespread fruit trees in the Mediterranean area. In the last years, the surface of olive orchards has increased considerably in Iran. Furthermore, cultivars used in these orchards are often foreign and little is known about their behavior under Iran climate conditions, especially about their tolerance to salinity. Hence, in order to study the effects of NaCl salinity on some morphological and physiological properties of one-year-old rooted cuttings of two olive cultivars (Mission (a foreign cultivar) and Mary (one of the most important Iranian cultivars)), a pot experiment was conducted in factorial based on randomized complete blocks design with four replications. Saline treatments were imposed by irrigation with water containing 0, 25, 50, 100 and 200 mM of NaCl. The results showed that NaCl salinity has significant effects on the parameters. The plants grow parameters (plant height, number and area of leaves, number and length of axillary shoots, stem diameter, fresh and dry weight of leaves and stems, dry weight of root) were decreased by increasing of NaCl concentration in irrigation water. Relative water content (RWC), chlorophyll content and leaf potassium concentration were decreased as well. However, converse effect was found in proline, total soluble sugars (TSS), and concentration of Na and Cl in leaves. Overall, the findings of this study showed that cv. Mission because of higher potassium concentration, chlorophyll content and RWC, higher accumulation of proline and TSS and lower concentration of Na and Cl in leaves was more resistant to salinity than cv. Mary.
 
Keywords: Growth parameters, Olive (Olea europea), Proline, Relative water content, Salinity