S05 - Session P2 - Induced drought and salt stress significantly affect morphological and eco-physiological response of Mediterranean wild roses

Authors: Youssef Rouphael *, Giancarlo Fascella, Massimo Mammano

Water scarcity and high soluble salts concentration in the irrigation water of ornamental crops are typical phenomena of nursery activities in the south Mediterranean districts and has frequently detrimental effects on plant growth, yield and quality. Actually, these two kinds of abiotic stress may lead to an excess of ballast ions and thus to biochemical and physiological unbalance resulting in reduced leaf chlorophyll content and net photosynthesis as well as in shoot dehydration and leaf chlorosis and abscission. Wild roses are generally hardy plants with high ornamental potentialities and possible tolerance to the main abiotic stresses typical of their native environments. Therefore, two greenhouse experiments were carried out with the aim to evaluate growing and qualitative response of three Sicilian rose species to increasing deficit irrigation and saline concentration of irrigation water. In the first experiment, plants derived from rooted cuttings of Rosa canina L., R. micrantha Borrer ex Sm and R. sempervirens L. were grown in 4-l plastic containers under drought stress induced by progressively reducing substrate water content (900, 600 and 300 ml plant -1 week -1 ) during each irrigation. In the second one, plants of the same species were grown in the same containers under salt stress induced by gradually increasing sodium chloride concentration (0, 40 and 80 mM NaCl) of the solution during each irrigation. Morphological and eco-physiological parameters were measured throughout both experiments. Reducing irrigation resulted in a decrease of plant growth (at canopy and root levels), ornamental effect, biomass yield and partitioning, stem water potential, leaf net photosynthesis and transpiration; this behavior was more evident in R. canina than in R. sempervirens potted plants. Similarly, increasing NaCl concentration of irrigation water resulted in a general reduction of plant growth, fresh and dry biomass, and ornamental value but did not affect the leaf SPAD index, showing significant difference among the three studied species. The identification of wild roses tolerant to moderate drought and NaCl concentration may allow to use them for ornamental nursery production and for landscaping in south Mediterranean areas often characterized by a low availability and scarce quality of the irrigation water.