NITRATES CONTENT IN CELLULAR EXTRACTS OF TOMATO PETIOLES AND FRUITS

Abstract

In this work we analyzed the nitrate contents in cellular extracts of petioles (ECP) and fruits of tomato (Lycopersicon esculentum, Mill) cv Sierra Madre an indeterminate  growth variety. Tomato seeds were germinated in “terra-lite” as growing medium and after 30 d the plants were transplanted to field conditions. Two irrigation systems were utilized (fertigation and furrow irrigation) and two fertilization levels (0 and 454 kg ha^-1 NO₃–N). The experiment was arranged in a complete block desing with four replications. The nitrogen was applied in variable dosages, according to the plant physiological stage (total N= 454 kg ha^-1 ). Nitrate concentration in petioles and fruits were determined every two weeks, from fruit set to the last harvest. High levels of nitrate in petioles and fruits were found mainly at the developing and ripening stages, in association with excessive a nitrate application to soil. Nitrate contents in petioles were 100 % higher then in similar reports and in fruits nitrate exceeded the permissible limit (60 mg kg^-1) of Europe and Russia.