University sheds light on plant growth

Researchers at the University of Sheffield have uncovered what determines how fast plants grow, and how evolution has adjusted this speed limit over millions of years, as the levels of the greenhouse gas carbon dioxide (CO2) has changed. Dr Peter Franks and Professor David Beerling from the University´s Department of Animal and Plant Sciences, have shed light on why some plants grow much faster than others under the same conditions. The ability of plants to grow depends on their absorption of atmospheric CO2 through microscopic pores (stomata) on the surface of leaves. Those species that can absorb CO2 more quickly are able to grow faster, and this capacity is set by the number and size of the pores. In the study, published in the Proceedings of the National Academy of Sciences (PNAS), the researchers analysed the fossil record of these pores reaching back in time nearly half a billion years. They showed that throughout the evolutionary history of plants, stomatal geometry (size and number) has changed dramatically. Dr Franks, lead author of the study, said: "The huge variation in stomatal size has been completely overlooked until now but has major implications for understanding plant evolution." The researchers also discovered that changes in the number and size of the pores were directly linked to the amount of carbon dioxide in the atmosphere.