20% - 30 %
||Arrivault S et al., Metabolite profiles reveal interspecific variation in operation of the Calvin-Benson cycle in both C4 and C3 plants. J Exp Bot. 2019 Mar 27 70(6):1843-1858. doi: 10.1093/jxb/erz051 p.1844 left column 2nd paragraphPubMed ID30773587
||Osmond CB. 1981. Photorespiration and photoinhibition: some implications for the energetics of photosynthesis. Biochimica et Biophysica Acta 639, 77–98 link AND Sharkey TD. 1988. Estimating the rate of photorespiration in leaves. Physiologia Plantarum 73, 147–152 link AND Long SP, Ainsworth EA, Leakey AD, Nösberger J, Ort DR. 2006. Food for thought: lower-than-expected crop yield stimulation with rising CO2 con-centrations. Science 312, 1918–1921 DOI: 10.1126/science.1114722 AND Betti M, Bauwe H, Busch FA, et al. 2016. Manipulating photorespiration to increase plant productivity: recent advances and perspectives for crop improvement. Journal of Experimental Botany 67, 2977–2988 doi: 10.1093/jxb/erw076 PubMed ID16809532, 26951371
||Primary source Sharkey abstract: "… the rate of photorespiration can be calculated from the rate of net CO2 assimilation and the partial pressures of CO2 and O2." Primary source Betti et al. abstract: "Here [investigators] summarize recent advances obtained in photorespiratory engineering and discuss prospects for these advances to be transferred to major crops to help address the globally increasing demand for food and biomass production."
||P.1844 left column 2nd paragraph: "In the current atmosphere with 0.04% CO2 and 21% O2, in C3 plants about every fourth reaction is with O2 instead of CO2, leading to a 20–30% decrease in the net rate of photosynthesis (primary sources)."