Low temperatures and corn development

​Low temperatures have been a major feature of this spring in northern US Corn Belt. Initial concerns are effects on germination and emergence but after emergence, heat energy affects several aspects of the corn plant. Studies have shown that hybrids vary in tolerance to cold temperatures.  Much of this involves the cellular membranes, including their ability to repair after membrane damage.  This affects loss of electrolytes and their function of nearly all cellular processes from photosynthesis to protein synthesis.  Many of the proteins are used as enzymes active in photosynthesis and cell duplication and elongation.  This generally results in reduced plant height and smaller leaves if plants grown at low temperatures than at higher normal plants.  Root volume is also less when corn plants grow under lower temperature environments.  This may be caused by a reduction of photosynthates reaching the root tissue.
 
Chlorophyll levels are lower when corn leaves are at lower temperatures, perhaps because of membrane damage and reduced syntheses of chlorophyll.  Reduction of photosynthesis is hypothesized to account for reduction of stomata and thus transpiration as well as CO2 movement into the plant.  Cellular respiration in which the glucose from photosynthesis is changed to a metabolically useful chemical energy (ATP) is also reduced, contributing to the reduced cellular elongation and duplication.
 
A study comparing commercial hybrids for tolerance to growth under low temperature environment was published in 2015 in Canadian Journal of Plant Science and can be found at 
https://www.nrcresearchpress.com/doi/full/10.1139/cjps-2015-0286#.XNnaYC_MxR4
 
Temperature is one of the factors that favor different hybrids each year.