INTERMITTENT SOLUTION CIRCULATION IN THE NUTRIENT FILM TECHNIQUE

It is possible to restrict the vegetative growth of early protected crops, growing in the nutrient film technique (NFT) of water culture, by supplying the nutrient solution intermittently. Regimes based on time clock or solar integration control were used on early tomato and cucumber crops. In the tomato, intermittent flow given up to anthesis of the fourth truss increased yield slightly and early fruit quality considerably. Continuing intermittent flow through fruiting diminished yield. In cucumber, a continuing regime of supplying the nutrient for 30 min every hour day and night increased yields by about 10%.

The intermittent flow technique had the additional advantage that it saved on pump wear and reduced electricity consumption by up to 84%.