| Light absorbed by photosynthetic pigments must be distributed either for chemical work, reemitted as fluorescence or safely dissipated as heat. Adverse environmental conditions reduce the dissipation capacity of plants and the excess energy leads to damage to the photosynthetic mechanism, termed photoinhibition. Low, non-freezing temperatures cause such photoinhibition, especially in tropical plants grown in the temperate zone. This damage occurs in the photosystem II and is triggered by highly reactive radicals or reactive forms of dioxygen. Numerous studies point to the involvement of oxygen and antioxidant enzymes and substrates in amelioration of these damages. In C;The goal of this research was to investigate the role of oxygen and antioxidants in low temperature photoinhibition by comparing two C;Our results show that oxygen imparted a significant protection to corn, but not Z. diploperennis, at low temperature. Nevertheless, Z. diploperennis sustained less photoinhibitory damage than corn. Photoinhibition in corn was accompanied by lower antioxidant concentrations. Both photosynthesis and antioxidants recovered by 2 days, suggesting that slow recycling of the latter induced photoinhibition at low temperature and retarded recovery. Maximum oxidation of the antioxidants took place in the presence of high light and low temperature. Chilling induced photoinhibition also required the presence of light. |
