S06 - Session O7 - Effects of different isosmotic salt solutions on growth, yield and mineral composition of hydroponically-grown Valerianella locusta.

Authors: Georgia Ntatsi *, Orfeas Voutsinos, Ioannis Karavidas, Dimitrios Petropoulos, Georgios Zioviris, Dimitrios Fortis, Beppe Benedetto Consentino, Andreas Ropokis, Leo Sabatino, Dimitrios Savvas

Nowadays there is an increasing interest in the hydroponic floating system cultivation of several leafy greens. This is ascribed mainly to the higher production yields, due to enhanced nutrient and water use efficiency, and the overall cultivation cost reductions. Floating could also be used to apply moderate salinity stress in order to increase the nutritional quality of fresh-cut leafy greens. In this study, we aimed to assess the effect of different types and rates of salinity on corn salad ( Valerianella locusta ) growth, yield and nutritional status. For this reason, five nutrient solutions were prepared: a basic nutrient solution used as control and four saline nutrient solutions. These solutions were prepared by adding to the basic nutrient solution, NaCl or CaCl2 at two concentrations (low and high). At each salinity level, the salt concentrations were iso-osmotic. The levels of the osmotic potential were calculated using the Van't Hoff's equation. Hence, the two concentrations for NaCl were 20 mM and 40 mM and for CaCl2 were 13.3 mM and 26.5 mM (low and high, respectively). The results showed that low NaCl salinity had no effect on both growth and yield compared to the control, while low CaCl2 decreased both parameters. Moreover, at high salinity, both salts were detrimental to the production of fresh plant biomass and leaf area, whereas the highest yield decrease was observed under high CaCl2 concentration in the nutrient solution. The shoot concentrations of Na + , Ca 2+ , and Cl - increased appreciably in the corresponding salinity treatments in comparison with the control when the concentrations of these ions in the external medium were high. The obtained results indicate that even though the dominant factor for the impact of salinity on corn salad is the osmotic potential level, the source salinity should also be considered accordingly.