Growth, sodium, and potassium uptake and translocation in salt stressed tomato

Salinity tolerance in some plant species has been related to characteristic s of potassium (K) and sodium (Na) uptake and transport. Tomato (Lycopersic on esculentum Mill., cv. Rossel) plants were grown in nutrient solution to determine effects of two K levels [0.2 (low) and 2 mmol(high)] combined wit h 0, 100, and 200 mmol NaCl on growth, and on Na and K uptake and transloca tion. Net uptake rates of Na and K were determined by disappearance in the growth medium and by plant accumulation. At the low level of K in solution, salinity decreased shoot and root dry weight and leaf area. Addition of 2 mmol K ameliorated of the added NaCl effects and improved growth parameters . Salinity reduced net K uptake rates and to a lesser extent K translocatio n from root to shoot, which resulted in higher K shoot concentration and a lower K root concentration. The inhibitory effect of salinity on K transloc ation was greater with low K level in nutrient solution. Net uptake of K wa s dependent on K level in the growth medium. Addition of K resulted in decr eases of shoot Na uptake. The translocation of Na from roots to shoots was reduced by K level in nutrient solution. These results indicate that K supp ly and K accumulation and regulation in plant tissue contribute to salt tol erance and growth enhancement.