Growth and quality response of potted ornamental shrubs under salt stress

High sodium chloride (NaCl) concentration in the irrigation water of greenhouse crops is a typical phenomenon of nursery activities in the south Mediterranean regions and has frequently detrimental effects on plant growth and quality as it may lead to an unbalance of some ions and thus to biochemical and physiological stresses resulting in reduced plant growth, leaf chlorophyll content and net photosynthesis. With the aim to assess the effects of this salt stress on crop responses, a greenhouse cultivation of three potted ornamental shrubs at increasing NaCl concentration (0, 40 and 80 mM) of irrigation water was conducted. Plants of Asteriscus maritimus, Euphorbia × lomi and Murraya paniculata were grown in 7-L containers using a mixture of sphagnum peat, perlite and red soils (1:1:1, v/v/v) under the same irrigation regime for avoiding water stress. Among the three species, the Mediterranean halophyte Asteriscus resulted the most tolerant to salt stress as highest values of many bio-morphological parameters (shoots emission, leaf area, biomass production) were recorded in plants irrigated with 80 mM NaCl, whereas lowest performances were observed in no-treated plants. Euphorbia and Murraya resulted moderately tolerant to salt stress as no significant differences on plant growth and physiological activities were found between control-plants and those irrigated with 40 mM NaCl, while lower values were measured under 80 mM NaCl treatment.