EFFECTS OF WATER DEFICIT ON PHOTOSYNTHESIS IN WHEAT PLANTS .3. EFFECT ON NONSTOMATAL MEDIATED PHOTOSYNTHESIS AND RUBP CARBOXYLASE CONTENT IN DIFFERENT PLANT-PARTS

In order to explore the physiological basis of the difference in photosynthetic depression by soil water deficit, the non-stomatal mediated photosynthesis (NSP) and ribulose-1, 5 bisphosphate carboxylase (RuBP-Case) content were compared among different parts of a wheat plant grown under soil water deficit condition. The depression of NSP due to water stress was larger in the lower leaf blades than in the upper ones, and in leaf blades than in ear, sheath and stem. The content of RuBPCase was decreased by soil water deficit to a larger extent in the lower leaf blades than in the upper ones, and in leaf blades than in stem and leaf sheath. But, in the ear, the extent of RuBPCase decrease was relatively large, compared with that of photosynthetic depression. The results here suggest a possibility that the difference among plant parts in photosynthetic depression by soil water deficit is partly attributed to the different sensitivity of photosynthetic apparatus to water stress. © 1990, CROP SCIENCE SOCIETY OF JAPAN. All rights reserved.