Long term responses of olive trees to salinity

• Published in: Agricultural water management 2009-07, Vol.96 (7), p.1105-1113
• Main Authors: Melgar, J.C., Mohamed, Y., Serrano, N., García-Galavís, P.A., Navarro, C., Parra, M.A., Benlloch, M., Fernández-Escobar, R.
• Format: Article
• Language: English
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agronomy. Soil science and plant productions; Biological and medical sciences; calcium; Calcium supply; chlorides; crop yield; cultivars; Drip fertigation; fruits (plant anatomy); Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; irrigation water; leaves; lipid content; Mediterranean climate; microirrigation; nutrients; Olea; Olea europaea; Olea europaea Salt tolerance Drip fertigation Calcium supply; olives; orchards; rain; saline water; salinity; Salt tolerance; sodium; soil salinity; soil water content; tree growth; tree physiology
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/j.agwat.2009.02.009

Water demand for irrigation is increasing in olive orchards due to enhanced yields and profits. Because olive trees are considered moderately tolerant to salinity, irrigation water with salt concentrations that can be harmful for many of fruit tree crops is often used without considering the possible negative effects on olive tree growth and yield. We studied salt effects in mature olive trees in a long term field experiment (1998–2006). Eighteen-year-old olive trees ( Olea europaea L.) cv. Picual were cultivated under drip irrigation with saline water composed of a mixture of NaCl and CaCl 2. Three irrigation regimes (i. no irrigation; ii. water application considering soil water reserves, short irrigation; iii. water application without considering soil water reserves and adding a 20% more as a leaching fraction, long irrigation) and three salt concentrations (0.5, 5 or 10 dS m −1) were applied. Treatments were the result of the combination of three salt concentrations with two irrigation regimes, plus the non-irrigated treatment. Growth parameters, leaf and fruit nutrition, yield, oil content and fruit characteristics were annually studied. Annual leaf nutrient analyses indicate that all nutrients were within the adequate levels. After 8 years of treatment, salinity did not affect any growth measurement and leaf Na + and Cl − concentration were always below the toxicity threshold of 0.2 and 0.5%, respectively. Annual and accumulated yield, fruit size and pulp:stone ratio were also not affected by salts. However, oil content increased linearly with salinity, in most of the years studied. Soil salinity measurements showed that there was no accumulation of salts in the upper 30 cm of the soil (where most of the roots are present) because of leaching by rainfall at the end of the irrigation period. Results suggest that a proper management of saline water, supplying Ca 2+ to the irrigation water, using drip irrigation until winter rest and seasonal rainfall typical of the Mediterranean climate leach the salts from the first 0–60 cm depth, and growing a tolerant cultivar, can allow using high saline irrigation water (up to 10 dS m −1) for a long time without affecting growth and yield in olive trees.