Thermal Inactivation of Plant Growth: Effects on Cotyledon Metabolism

Temperature exposures which normally decrease growth of Pisum sativum seedlings by 50 % were found to be lethal in plants whose cotyledons were removed. Utilization of the two major reserves, starch and protein, decreased at high temperatures. However, the two enzymes responsible for their hydrolysis were thermostable. It appears that the influence of high temperatures on seedling growth is not due to direct effects of temperature on cotyledon metabolism, but rather indirectly through the axis.