Abstract. Short- and long-term effects of elevated CO 2 concentration and temperature on whole plant respiratory relationships are examined for wheat grown at four. Photosynthesis is a process in which light energy is used to produce sugar and other organic compounds. Photosynthesis and Photorespiration in Whole Plants of Wheat. 18 O 2 was used to measure the O 2 uptake by the plant. was as important as the net photosynthesis. Photosynthesis, Biomass, and Yield in Crops. More than 90% of crop biomass is derived from photosynthetic products. Therefore, many crop scientists have believed that. 402 Journal of Food, Agriculture & Environment, Vol.7 (3&4), July-October 2009 part from the plant, was different among plant parts. Although it is It is a major diet component because of the wheat plant's agronomic adaptability with the. as this leaf represents about 75% of photosynthesis reactions during. The photosynthetic efficiency is the fraction of light energy converted into chemical energy during photosynthesis in plants and algae. Photosynthesis can be. Photosynthesis Experiment and System Testing and. of the dwarf wheat plant in microgravity and. and whole canopy photosynthesis on dwarf wheat. Unidirectional O 2 fluxes were measured with 18 O 2 in a whole plant of wheat cultivated in a controlled environment. At 2 or 21% O 2, O 2 uptake was maximum at 60. Plant Physiol. (1979) 64, 735-738 0032-0889//04/$00.50/0 Photosynthesis and Photorespiration in Whole Plants of Wheat Received for publication February 27.