EFFECT OF THE ADDITION OF ACTIVATED-CHARCOAL TO THE NUTRIENT SOLUTION ON THE GROWTH OF TOMATO IN HYDROPONIC CULTURE

The addition of activated charcoal to a nutrient solution for the hydroponic culture of tomato resulted in both a considerable decrease in the carbon concentration in the solution and significant increases in the dry weight of plant and in fruit yield. No appreciable changes were brought about in the concentrations of major and trace elements both in the solution and in the plant by the addition of activated charcoal. The nutrient solution collected after the cultivation without activated charcoal was toxic to the growth of tomato seedlings and to the germination of tomato seeds. No toxic effect was observed for the residual nutrient solution treated with activated charcoal. These facts indicate that the growth of tomato in hydroponic culture is inhibited by organic substances which arise from the root exudates and are removed from the nutrient solution by adsorption on activated charcoal.