Phosphorus Rate in Combination with Cultural Practices Reduces Excessive Growth of Tomato Seedlings in the Float System

Abstract

Conventional tomato (Lycopersicon esculentum Mill.) seedling production can be labor intensive. The float system of production may be a less labor-intensive alternative. Float system technology is used extensively to produce tobacco seedlings, but is currently used very little for horticultural crop seedlings. Potential advantages of the float system include lowered production cost, more efficient use of water and nutrients, elimination of wetting of plant foliage thus reducing disease, and elimination of nutrient leaching to groundwater below the greenhouse. When grown in float culture using a tobacco nutritional regimen, tomato seedlings produced undesirably long stems. Greenhouse experiments were conducted to identify production practices that may limit this excessive growth. Practices evaluated included two fertilizers with either 2.2% or 0.87% P combined with brushing, clipping once, ethephon application, delay of fertilization for 10 days after seeding, brushing combined with delayed fertilization, and two levels of air movement. Greatest height control was obtained with a combination of practices. Most height control practices, except delayed fertilization (with nor without brushing), were more effective if combined with low P fertilizer. The combination of brushing with delayed fertilization using either fertilizer provided the best height control and the highest quality seedlings. Ethephon and brushing in combination with low P fertilizer were also effective. These experiments show that with use of height-limiting management techniques good quality tomato seedlings can be produced in the float system. The experiment did not address the field performance of the seedlings.