Salt tolerance of ornamental shrubs mainly used in the Mediterranean landscape

Ornamental nursery production is a sector of increasing importance in Mediterranean countries, particularly in Sicily. However the rising demand of water for urban, touristic and industrial use restricts the availability of irrigation water of good quality for the irrigation of greenhouse ornamental crops. Thus, identifying salt tolerance in ornamental species is a prerequisite to use saline water in agriculture saving good quality fresh water for domestic consumption. Despite the importance of ornamental shrubs for salt affected areas, the salt tolerance of these species has received little attention. The study was undertaken to evaluate the effect of saline water on the growth and decorative value of some ornamental shrubs (Cestrum aurantiacum, Cotoneaster lacteus, Eugenia myrtifolia, Pyracantha ‘Harlequin’, Teucrium fruticans). Plants were exposed for a six month period to increasing EC levels (1.8, 4.8 and 7.8 dS m-1). Dry biomass accumulation, leaf area and leaf chlorophyll content were recorded every eight weeks from the beginning of the salt treatment. Growth indexes were also calculated. Salt-induced leaf necrosis was assessed visually. Results obtained showed that plant growth, expressed by dry weight, number of leaves and leaf area, was significantly influenced by salt stress treatment. Cotoneaster was found to be the most salt sensitive species as indicated by the large occurrence of leaf necrosis. Cestrum and Pyracantha exhibited a reduced growth under salinity condition but the plants showed only slight necrosis on their foliage. Teucrium and especially Eugenia were able to cope with salt stress and to maintain their decorative value.