Effect of Changes in Root Zone Temperature on the Subsequent Growth and Development of Young Corn Plants1

Abstract

AbstractCorn plants were grown to defined stages of shoot development in sand culture at root zone temperatures of 15, 20, and 25C from emergence. Some plants were grown at constant root zone temperatures and others were transferred to the other two root zone temperatures at the 2‐leaf and 4‐leaf stages and then grown to the 4‐leaf and 6‐leaf stages, respectively.The dry weights of the shoots and roots decreased with increasing root zone temperatures at similar leaf stages. Although relative growth rates and absolute growth rates were generally correlated, the latter were chosen on a rational basis to indicate the effects of root zone temperature changes on the rate of dry matter accumulation. The rate of morphological development of the plants increased substantially with increasing root zone temperatures. On the other hand, absolute growth rates of both the shoots and roots tended to be greatest at 20 and lowest at 25C. The optimum root zone temperature apparently decreased for shoot growth but increased for root growth during the 2‐leaf to 6‐leaf stage interval. The previous root zone temperature had a variable influence on subsequent growth for all three temperatures. This effect was difficult to explain but depended somewhat on the corn variety.