Critical Soil Temperature for Tomato Plant Growth

Fireball and Kokomo variety of tomatoes were used to study the effect of root temperatures at 56°, 58°, 60° and 70°F., and of P concentration on plant growth and chemical composition. It was found that the early and late tomato varieties responded similarly to the respective root temperatures. The response to P fertilizer was between 5 and 50 ppm., with no further growth increase at 100 ppm. There was a growth increase as expressed by dry weight between 56° and 58° and 58° and 70°F., but not between 58° and 60°F. Although in all cases increasing the temperature from 56° to 58°F. increased nutrient uptake, the difference was not great enough to have any practical importance. The growth of tomato shoots was doubled by increasing the root temperature from 56° to 58°F.