EFFECT OF ROOT ZONE TEMPERATURES ON CORN LEAF MORPHOLOGY

Abstract

Corn plants were grown at constant root zone temperatures of 15°, 20°, and 25 °C using sand culture in the greenhouse. Stages of development were defined, using as a basis the appearance of leaf tips from the whorl, so that morphologically similar plants grown at different root zone temperatures could be compared.The time intervals required by the corn plants to reach specific stages of development increased substantially with decreasing temperatures. The total dry weights of the plants at specified stages of development decreased significantly with increasing temperatures. Plants grown at 25° produced on the average 1.7 leaves more than those grown at 15 °C prior to tassel formation. Lamina lengths and dry weights decreased with increasing temperatures. Lamina widths and areas were greatest at 20 °C. The narrowest laminae were produced by plants grown at 15° and smallest lamina areas at 25 °C. While the diameters of one cell type in the laminae were not affected by temperature, the lengths of two other cell types decreased significantly with increasing temperatures.The variations in morphological characteristics of leaf laminae were interpreted on the premise of a direct influence of root zone temperature on the shoot meristem.