Short‐ and Long‐term Effects of High Temperatures (47–49 °C) on Tobacco Leaves. I. Photosynthesis

Abstract

Abstract Detached Nicotiana rustica leaves were exposed for 2 minutes to temperatures in the range 36° to 51°C. Above 45°C, 14 CO 2 fixation was reduced by half as compared with controls. The fall in 14 CO 2 fixation continued for 2 1/2 h. Recovery was completed 45 h after the treatment. Above 45°C there was an increase in the labeled cationic and anionic fractions and a decrease in the neutral fractions, both increase and decrease being associated with the impaired CO 2 fixation. However, these changes in products were also demonstrated when leaves were exposed to the high temperature after labeling.