GROWTH ANALYSIS OF TOMATO IN A CLOSED RECIRCULATING SYSTEM IN RELATION TO THE EC-VALUE OF THE NUTRIENT SOLUTION

The salinity of nutrient solutions, controlled by electrical conductivity (EC), has increased in recent years, especially in the production of high-quality fruit vegetables, such as tomatoes.

The aim of the present study was to determine the effect of EC on growth characteristics of tomato (cv.
Counter, Selfesta, Vanessa) under commercial conditions during a 7-month period.
The hypothesis that higher EC levels result in decreased growth was tested.
A Nutrient Film Technique (NFT) was used to regulate water and nutrient supply in a 1500 m² greenhouse.
Six EC values were investigated in the NFT-experiment: 1.6, 5.3 and 7.1 dS m^-1 in 1994 and 1, 3.5 and 6 dS m^-1 in 1995. Supply of nutrient solution was increased with increasing global radiation.

The results showed under commercial conditions differences in the yield but not in the total dry weight irrespective of EC level.
At the highest EC, yield was 52 % in 1994 and 64 % in 1995 compared to that of plants grown at the lowest EC. With increasing EC growth parameters such as absolute growth rate, net assimilation rate, flowering rate, leaf area index, leaf size and fruit weight decreased although not always significantly.
A linear relationship between dry matter content of the fruits as well as nitrogen content and EC was observed independent of harvesting date and experimental year.
Linear relationships existed between EC in combination with global radiation and each of the parameters fruit weight, leaf size, generative and vegetative weight ratio and root dry weight.

International Symposium Growing Media and Plant Nutrition in Horticulture

D. Schwarz, R. Kuchenbuch

global radiation, Lycopersicon lycopersicum, Nutrient Film Techniques, salinity, varieties

https://doi.org/10.17660/ActaHortic.1997.450.19