THE EFFECT OF OSMOTIC STRESS ON THE YIELD AND QUALITY OF TOMATOES

1. to determine whether it was possible to improve the quality of tomatoes, both in the field and in the greenhouse by the modification of osmotic stress.
2. to quantify the relationship (if any) between yield and quality
3. to examine the effect of genotype and season on this relationship.

In heated greenhouse studies tomatoes were grown using a range of osmotic levels using either the Nutrient Film Technique (NFT) or a pumice based system in which the nutrient solutions were applied to waste (in a similar manner to the rock wool system).

Increasing osmotic stress in the medium reduced yield (primarily due to a reduction in fruit size) and improved quality based on laboratory measurements of sugar content (Brix) or by taste panel.

There were also marked genotypic and seasonal effects when the tomatoes were grown using a single truss (as opposed to a multiple truss) system.

These results have considerable practical implications by offering growers the opportunity of producing tomatoes of far higher quality (in terms of taste) by using a controlled osmotic regime.

In the field experiment tomato quality was improved by the incresed osmotic regime, without any reduction in yield.

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