High temperature reduces the positive effect of elevated CO2 on wheat root system growth

Increases in atmospheric carbon dioxide concentration ([CO2]) and temperature associated with future climates are expected to affect wheat growth and grain yield. The ability of wheat to adapt to these changes is close related to the response of the root system. The effect of elevated CO2, high temperature and the interaction elevated CO2×high temperature (3°C above the ambient temperature) on the growth and proliferation of the root system of two spring wheat genotypes differing in vigorous growth was evaluated. The breeding line Vigor 18 selected for vigorous shoot and root growth and the commercial cultivar Janz were grown in rhizo-boxes inside specially designed tunnel houses under ambient (390-400μLL-1) and elevated CO2 (700μLL-1), and ambient and 3°C above the ambient temperature. Growth and proliferation of the root system was monitored through root mapping. Elevated CO2 enhanced root and shoot biomass, but this positive effect was reduced when plants were grown under high temperature. Total root length was also increased by elevated CO2, but only when plants were grown under ambient rather than under high temperature. Root growth response to elevated CO2 differed between genotypes; elevated CO2 stimulated root growth in the non-vigorous cultivar Janz, but not in vigorous liner Vigor 18. High temperature reduces the positive effect that elevated CO2 has on root growth and proliferation. © 2014 Elsevier B.V.