Appropriate Root-zone Temperature Control in Perlite Bag Culture of Tomato during Winter Season

The effective method for heating root-zone during winter season was studied in the aspects of growth, yield and economics for tomato (Solomon lycopersicum) in perlite bag culture. There were four root-zone heating treatments: two hours heating from one hour before to one hour after sunrise, four hours from two hours before to two hours after sunrise, 15 hours after sunset, and no heating. The growth characteristics of the upper parts of plants were not significantly different among the treatments, but root volume increased with longer heating of the root zone. The Plant Development Index, using stern diameter and the length between growing tip and the upper flowering truss, showed relation between yield per cluster and growth pattern. The treatment heating for four hours was the most economic in terms of growth and yield of tomato.