Abstract
Tomato plants (Lycopersicon esculentum Mill., cv. House-Momotaro) were grown for 9 months from September to June in a conventional open rockwool system or in a similar system equipped with a solution-recycling unit that we devised to reduce environmental pollution with drained nutrient solution. Concentrations of nutrients in the rockwool slub solution differed with the systems; P, K, Ca and Mn concentrations were lower and B and Na concentrations were higher in the solution-recycling system than in the open system. Nevertheless, concentrations of major nutrients and Na in leaves did not greatly differ between systems. Furthermore, plant growth and crop yield in the solution-recycling system were similar to those in the open system. These findings show that the solution-recycling unit attached to a commercial open rockwool cultivation system makes it possible to reduce environmental pollution by discarded nutrient solutions without reducing the yield on long-term cultivation of tomato plants.
