Activity of aminotransferase in tomato seedlings depending on Ca : Mg ion ratio in the nutrient medium

Abstract

Change from the normal Ca : Mg ion ratio (3 :1) to 3 : 30 in a medium in the presence of nitrates causes reduction of dry weight content in the tomato seedlings. This reduction is not observable if ammonium salts are the source of nitrogen. It was found that the GOT and GPT activity depends on the form of mineral nitrogen and on the Ca : Mg ion ratio in the medium. An excess of magnesium causes a distinct decrease of the activity of both enzymes in roots of plants grown in nitrate media. In the remaining organs of the plants the GOT activity tends to grow at increased magnesium dose in the medium in the presence of nitrates. Excess of Mg²⁺ ions in the medium containing ammonium salts increases the activity of GPT in the roots of the tomato seedlings and the GOT activity in the roots, shoots and leaves of tomatoes. The possibility of indirect influence of the Ca : Mg ratio in the medium upon the activity of both enzymes has been discussed.