INFLUENCE DE LA CONDUCTIVITÉ ÉLECTRIQUE DE LA SOLUTION NUTRITIVE SUR LA CROISSANCE ET LE DÉVELOPPEMENT DE LA TOMATE DE SERRE CULTIVÉE AVEC OU SANS ÉCLAIRAGE D’APPOINT

Abstract

Tomato plants (Lycopersicon esculentum Mill. ’Vendor’ and ’Carmelo’) were cultivated under different electric conductivities (2, 4 and 6 mS cm−1) of a continuously or intermittently supplied nutrient solution. The plants were grown in an NFT system, with or without supplementary lighting using high-pressure sodium (HPS) lamps. Raising electric conductivity reduced the shoot dry weight but increased root dry weight. The number of fruit on the first truss and the fruit weight were not affected significantly by electric conductivities. The use of supplementary lighting with an electric conductivity of 6 mS cm−1 increased the number of marketable fruit. High electric conductivity modified the mineral composition of leaf tissue mainly P, Ca and Mg. The vegetative growth was reduced and better yield was obtained with tomato plants grown under supplementary lighting and high electric conductivity.Key words: Tomato, supplementary lighting, nutrient solution, HPS, electric conductivity, salinity