Towards resilient crop production in changing climates: a system approach for understanding carbon-nitrogen interactions at elevated atmospheric CO2 concentrations

Interactions between carbon (C) and nitrogen (N), two of plants' most important building blocks, have been frequently investigated in crops and soils. In this research they receive renewed attention in the context of climate change. The observed and expected further rise of CO2 concentrations in the air mean more C availability for crops to create biomass. At the same time, the higher CO2 concentrations in the air also cause the pores of the crop leaves to remain more closed thus less water is lost by transpiration. Yet, crops may not always profit fully from this beneficial CO2 effect, partly due to limited 'sink strength', which is the capacity of the crop to use the carbon for its growth. Shortage of N, an important plant nutrient that is available to the crop from the soil, is assumed to be partly responsible for this. High CO2 concentrations can for example alter the growth of crop roots belowground and as such the amount of N a crop can take up from the soil. The interactions between C and N will be studied in a greenhouse under different levels of CO2 and N. The results from these experiments will then be used to understand and explain observations made in the field. Together, these will contribute to improve computer models that simulate crop growth.