Response of tomato plants to saline water as affected by carbon dioxide supplementation. I. Growth, yield and fruit quality

Tomato plants (Lycopersicon esculentum (L.) Mill. cv. F144) were irrigated with low concentrations of mixed salts; the highest level (E.C. 7 dS m(-1)) simulated conditions used to produce quality tomatoes in the Negev highlan ds. CO2 enrichment (to 1200 mu mol mol(-1), given during the daytime) incre ased plant growth at the early stage of development. However, later growth enhancement was maintained only when combined with salt stress. In the abse nce of CO2 supplementation, overall growth decreased with salt (7 dS m(-1)) to 58% and fresh biomass yields to 53% of the controls. However, under ele vated CO2 concentrations total plant dry biomass was not reduced by salt st ress. CO2 enrichment of plants grown with 7 dS m(-1) salt increased total f resh fruit yields by 48% and maintained fruit quality in terms of total sol uble salts, glucose and acidity. Fruit ripening was about 10 d earlier unde r CO2 enrichment, regardless of salinity treatment. It is suggested that a combined utilization of brackish water and CO2 supplementation may enable t he production of high-quality fruits without incurring all the inevitable l oss in yields associated with salt treatment.