Effects of Saline Stress and Ca2+/K+ Interaction on Biomass and Mineral Contents of Tomato

'Raf' is a traditional tomato cultivar in the province of Almeria (Spain) needing specialised management. It requires high electrical conductivity (EC) in the nutrient solution and a high hydric stress to produce high quality fruits. The present paper evaluates the effects of saline stress and Ca2+/K+ interactions on biomass production and mineral nutrient contents of a 'Raf' tomato crop grown in perlite in greenhouse conditions. Crop management and nutrient solution were those habitually employed in this area, maintaining the Ca2+:K+ ratios stable for each treatment. Samples were taken 100 and 141 days after transplanting to determine dry biomass, hydric content of roots, stem and leaves, leaf area and the nutrient content in stem and leaves. Results show that a high salinity level reduces leaf area, hydric content and dry biomass content in the whole plant except roots. On the other hand, low Ca2+:K+ ratios increase the dry weight of roots and stem and reduce the hydric content in stem and fruits. The highest Ca2+:K+ ratio gave rise to the highest values of Na, Cl, P and Ca and the lowest K values in both leaves and stem. However, the highest salinity level resulted in the lowest values of S, K and Ca in leaves and stem, but increased contents of Na and Cl in leaves and stem, and of Mg only in leaves.