Interactive effects of soil temperature, atmospheric carbon dioxide and soil N on root development, biomass and nutrient uptake of winter wheat during vegetative growth

Nutrient requirements for plant growth are expected to rise in response to the predicted changes in CO2 and temperature. In this context, little atten tion has been paid to the effects of soil temperature, which limits plant g rowth at early stages in temperate regions. A factorial growth-room experim ent was conducted with winter wheat, varying soil temperature (10 degreesC and 15 degreesC), atmospheric CO2 concentration (360 and 700 ppm), and N su pply (low and high). The hypothesis was that soil temperature would modify root development, biomass allocation and nutrient uptake during vegetative growth and that its effects would interact with atmospheric CO2 and N avail ability. Soil temperature effects were confirmed for most of the variables measured and 3-factor interactions were observed for root development, plan t biomass components, N-use efficiency, and shoot P content. Importantly, t he soil temperature effects were manifest in the absence of any change in a ir temperature. Changes in root development, nutrient uptake and nutrient-u se efficiencies were interpreted as counterbalancing mechanisms for meeting nutrient requirements for plant growth in each situation. Most variables r esponded to an increase in resource availability in the order: N supply >so il temperature >CO2.