Abstract
In all the experiments the best development of tomato plants was observed when nutrient solutions containing 1/3 of full doses of potassium were applied (i.e. when the N : K ratio = 0.84). On the other hand, the poorest development of plants was observed in combinations with 1/100 of the full potassium dose. Tenfold doses of potassium added to the nutrient solution de-pressed markedly plant growth, particularly at pH 7.6. The supply of potassium in the nutrient solution was correlated with the nitrogen, potassium and calcium amounts absorbed by the plants.