The effect of sodium humate on the content of different types of phosphorus compounds and on the activity of acid phosphatases in tomato seedlings

Abstract

The effect of sodium humate on the level of some fractions of phosphorus compounds in the leaves and roots of tomatoes cultured in mediums with a full or reduced phosphorus dose was studied. A dependence was found between the presence of humate in the medium and an increase in the amount of some organic phosphorus compounds in the leaves (lipid phosphorus, easily hydrolyzed phosphorus compounds, nucleic acid phosphorus). In addition, humate lowered the activity of acid phosphatases which had been excessively increased due to the plants inadequate phosphate supply. The results suggest that Na-humate affects phosphorus metabolism not only in an indirect manner, but also directly through penetration of humic substances into the plant tissues.