Chilling injury and changes in adenosine triphosphate of cotton seedlings.

Young Gossypium hirsutum L. seedlings chilled at 5 degrees showed a continual decrease in ATP concentration with time of chilling. Chilled plants returned to optimum conditions were able to restore the initial ATP concentration when chilled only 1 day, but not when chilled 2 days. The decrease in ATP with chilling was prevented by hardening the seedlings at 15 degrees for 2 days (14-hr-day-length) immediately before chilling. The ATP level of hardened plants was higher than of unhardened plants. When hardened plants were chilled at 5 degrees , the ATP level increased in the leaves but decreased in the roots.A mechanism of chilling injury is discussed in relation to the decrease in ATP concentration at low temperature.