Tomato growing in saline conditions with biodesalinating plants: Salsola soda L., and Portulaca oleracea L

In order to evaluate the effects of Salsola soda L. and Portulaca oleracea L. used as companion plants on growth and yield of tomato (Lycopersicon esculentum Mill.) in salt stress conditions, a trial was conducted in soil-filled benches of a greenhouse in Central Italy. The plant combinations were tomato alone, Salsola soda L. alone (50 g m-2 seeds), Portulaca oleracea L. alone (10 g m-2 seeds), tomato with Salsola soda L. (50 g m-2 seeds), tomato with Salsola soda L. (75 g m-2 seeds), tomato with Portulaca oleracea L. (10 g m-2 seeds) and tomato with Portulaca oleracea L. (15 g m-2 seeds). The Electrical Conductivity (EC) of irrigation water was 1.3 dS m-1 and 6.5 dS m-1 for control and water treatment, respectively. In saline conditions, the Salsola soda L. and Portulaca oleracea L. companion plants determine an increase of 22% and 33% in tomato yield in comparison with tomato alone. At higher sowing density (75 g m-2), Portulaca oleracea L. reduced the growth and the yield of the control. In NaCl salt stress, Na concentration in tomato leaves was significantly reduced by 39.6 % and 35.6 % in tomato grown with Salsola soda L. and Portulaca oleracea L. respect to tomato alone. A Cl content reduction was found only with Salsola soda L. at sowing density of 75 g m-2. No effects was found for N, K and Mg content in tomato grown with companion plant compared to tomato alone under salt-stress. P showed less reduction in saline condition when tomato was grown with both halophytes. A higher Ca content was observed in tomato leaves in the presence of companion plants under saline stress. The growth of Salsola soda L. was slower than Portulaca oleracea L., but the final plant weight resulted higher in Salsola soda L. in saline conditions. The higher yield obtained in tomato growing with companion plants under salt-stress may be due to a reduction of Na absorption and an increase of P and Ca uptake.