Abstract: After full expansion of flag leaf, the photosynthetic functional dec line process was divided into active photosynthetic duration and sharp fall phas e. During the active photosynthetic duration,the PS　Ⅰ particles ma intained high er electron transport activities. The polypeptide components of PS

Key words: Light-temperature stress, Yangmai No.5(Triticum aestivum L.), Photosynthe -tic f unctional decline process, PS　Ⅰ particles, Polypeptide component, Electron transport activity