Experimental plant research and the discovery of carbon dioxide-mediated global greening: a tribute to Wilhelm Pfeffer (1845–1920)
By U. Kutschera and R. Khanna
One century ago, the German chemist and botanist Wilhelm Pfeffer (1845–1920) died, shortly after finishing his last lecture at the University of Leipzig. Pfeffer was, together with Julius Sachs (1832–1897), the founder of modern plant physiology. In contrast to Sachs, Pfeffer’s work was exclusively based on the principles of physics and chemistry, so that with his publications, notably the ca. 1.600 pages-long Handbuch der Pflanzenphysiologie (2. ed., Vol. I/II; 1897/1904), experimental plant research was founded. Here we summarize Pfeffer’s life and work with special emphasis on his experiments on osmosis, plant growth in light vs. darkness, gravitropism, cell physiology, photosynthesis and leaf movements. We document that Pfeffer was the first to construct/establish constant temperature rooms (growth chambers) for seed plants. Moreover, he pioneered in outlining the carbon-cycle in the biosphere, and described the effect of carbon dioxide (CO2)-enhancement on assimilation and plant productivity. Wilhelm Pfeffer pointed out that, at ca. 0.03 vol% CO2 (in 1900), photosynthesis is sub-optimal. Accordingly, due to human activities, anthropogenic CO2 released into the atmosphere promotes plant growth and crop yield. [Emphasis added] We have reproduced Pfeffer’s classical experiments on the role of CO2 with respect to plant development, and document that exhaled air of a human (ca. 4 vol% CO2) strongly promotes growth. We conclude that Pfeffer not only acted as a key figure in the establishment of experimental plant physiology. He was also the discoverer of the phenomenon of CO2-mediated global greening and promotion of crop productivity, today known as the “CO2-fertilization-effect”. These topics are discussed with reference to climate change and the most recent findings in this area of applied plant research.
This article appeared on the Journal of Plant Biochemistry and Biotechnology website at https://link.springer.com/article/10.1007/s13562-020-00644-y]]>