I have been receiving calls about what the cool night temperatures we have recently been experiencing might do to corn grain yields. Most farmers believe that corn grows best when the nights are hot. The reverse is true.
Corn uses more energy in cell respiration on warm nights resulting in lower yields.
Leaf temperatures are influenced by the sky condition. On a clear night, the leaf radiates heat into outer space at a rapid rate and cools quickly. This is observed when heavy dew forms early on leaves at night. When clouds are present, the leaf temperature is the temperature of the cloud cover, which is always warmer than outer space and dew forms later if at all. Very high humidity has much the same effect as a cloud cover.