Effets de l'adjonction de KCl ou de CaCl2 sur la tolérance au NaCl chez deux cultivars de triticale (Clercal et Beagle)

The effects of salinity on growth along with water and ion relations were studied on two cultivars of triticale (Clercal and Beagle) after 21 days of growth under controlled conditions in nutrient solutions with or without 150 mM NaCl, and on nutrient solutions with 150 mM NaCl + 20 mM KCl or 150 mM NaCl + 20 mM CaCl2. Growth was strongly affected by an increased NaCl concentration in the culture medium, causing a water deficit linked to a drop in water (ψ) and osmotic (π) potentials, followed by an accumulation of Na+ and a reduction of K+ in the aboveground part of the triticales. Addition of KCl or CaCl2 to NaCl-containing media improved NaCl tolerance of the plant: growth increased more than 30%, hydration of tissues improved, and K+ uptake was normal, as seen by an increased K+/Na+ selectivity ratio in the aboveground parts. The two cultivars did not show the same degree of tolerance on these media. The protection afforded by KCl or CaCl2 in the NaCl-containing media was more significant for 'Clercal' than for 'Beagle'. Moreover, it seems that in presence of KCl or CaCl2, the improved K+ uptake was greater in 'Clercal' than in 'Beagle'. It is therefore possible that 'Beagle' requires less K+ than 'Clercal' for normal cell functioning. It is suggested that the K+/Na+ selectivity ratio is critical for salinity tolerance in the triticales.