The effect of saline water on Phillyrea angustifolia L. seedlings

Water limitations in the Mediterranean areas are very common and the use of saline water for plant irrigation is becoming a necessity. Salinity generally affects plant growth and physiological processes, and can eventually lead to leaf injuries and plant death. For these reasons, the selection of salt tolerant species is a priority for landscaping purposes in the Mediterranean areas. The objective of this study was to evaluate the effect of saline water on Phillyrea angustifolia plant performance. Seventy-five rooted cuttings were grown in the greenhouse in 4-liter pots and irrigated for 5 months with saline water at different NaCl concentrations for two consecutive years. In 2010, 45 plants were irrigated with 0, 40 and 80 mM NaCl water; in 2011, 30 plants were irrigated with 0, 100 and 120 mM NaCl water. No signs of leaf injury were observed in any of the two years or at any NaCl concentration. On the other hand, photosynthetic rates and stomatal conductances were reduced at all NaCl concentra¬tions. Reductions in shoot elongation were significant in both years, while shoot diameter growth and dry weights were affected only by high NaCl concentrations in the second year. In 2011, plant dry weight was reduced by 52% at 100 mM NaCl and 55% at 120 mM NaCl. Roots were highly susceptible to NaCl with a biomass reduc¬tion of 64 and 66% at 100 and 120 mM NaCl, respectively. Both leaf area and dry weight were influenced by NaCl with a reduction of over 50% at 120 mM NaCl. No significant effect was observed in biomass partitioning with the exception of a decrease of partitioning to roots at the highest salt concentrations. Phillyrea angustifolia plants were able to survive to all ranges of NaCl tested but CO2 fixation and shoot elongation rates were already reduced by moderate salt concentrations.