Growth and Photosynthetic Response of Tomato to Nutrient Solution Concentration at Two Light Levels

in Journal of the American Society for Horticultural Science
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  • 1 Institute for Vegetable and Ornamental Crops, D-14979 Großbeeren, Theodor Echtermeyer Weg 1, Germany
  • | 2 The University of Georgia, College of Agriculture and Environmental Science-Griffin Campus, Department of Horticulture, 1109 Experiment Street, Griffin, GA 30223-1797

An increase in nutrient solution concentration to produce high-quality fruit vegetables, such as tomatoes, may reduce growth and yield. One reason might be inhibition of photosynthesis, but results of photosynthesis studies in the literature are inconsistent. In this study, we investigated growth and photosynthesis of whole `Celebrity' and `Counter' tomato [Lycopersicon esculentum (L.) Mill.] plants in response to nutrient solution concentration, measured as electrical conductivity (EC). The effects of two levels of photosynthetic photon flux density (PPF = 400 or 625 μmol·m-2·s-1) on plant response to nutrient solution EC in a range between 1.25 to 8.75 dS·m-1 in a series of four experiments in gas exchange chambers placed in larger growth chambers were examined. Increasing PPF enhanced tomato growth and photosynthesis but increasing EC diminished them. Reduction of dry weight was 1.9% to 7.3%, while plant photosynthesis was reduced between 1.7% and 4.5% for each 1 dS·m-1. Increasing EC did not decrease dry matter content and leaf photosynthesis. Mean plant dry matter content ranged between 70 and 95 g·kg-1, and net leaf photosynthesis on the last measurement day was between 7.5 and 11.3 μmol·m-2·s-1, depending on experiment. The decrease in whole plant photosynthesis with an increase in EC was caused by decreased leaf area but not by a decrease in leaf photosynthesis.

Contributor Notes

Corresponding author. Mailing address: Institute for Vegetable and Ornamental Crops, Großbeeren/Erfurt e.V., Theodor Echtermeyer Weg 1, D-14979 Großbeeren, Germany; e-mail Schwarz@igzev.de.
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