Design of a joint experimental and modelling platform to improve understanding of mechanisms and impacts of abiotic and biotic stress interactions in cereals

A deeper understanding of the mechanisms underlying the impacts of multiple stresses in crops is direly needed given the climate change-induced risks to achieving food security for a growing world population. Global warming has already led to a higher frequency of multiple stresses occurring concurrently or subsequently and will continue to do so for the next decades. Plant-stress interactions are commonly subdivided into abiotic and biotic stresses and studied separately. Under field conditions, these stress interactions are usually multiple and interactive in character.To date, the mechanisms determining interactions between abiotic and biotic stresses and their effects on crop performance are unknown for most crops and stress combinations. Field data are particularly scarce as most studies have focused on laboratory model systems using few environmental parameters in controlled conditions, which cannot reflect the dynamics in the field. Adequate modelling approaches capable of describing basic crop growth processes and simultaneously capturing response to abiotic and biotic stress interactions and their impacts on crop yield and quality do not exist so far.The aim of this paper is to present the design of a joint experimental and modelling platform (MultiStress) capable of creating a deeper understanding of the overall impact of combined (abiotic+biotic) stresses on crop physiology and productivity (grain yield, biomass, grain and stover quality, nutrient/water use efficiency, etc.) using the cereal maize as one of the most important crops globally as a model.The empirical knowledge gained from the experimental set-up and formalized in an associated modelling platform is utilized to define traits for stress tolerant breeding to be considered in ideotyping cereal cultivars for future target environments. In our example, in a research Pillar I, we describe a field experimental platform (with rainout shelters) applicable under temperate and tropical climate conditions to investigate the interactions of drought and nitrogen deficiency with the foliar disease Northern Corn Leaf Blight caused by Setosphaeria turcica on the one hand, and stem borer caterpillars on the other.  Pillar II is an associated process-based modelling platform enabling integration of new genetic and ecophysiological knowledge and extrapolate the findings in time and space.Applying a systems approach in conjunction with this platform we can test the following hypotheses: (i) the impact of combined abiotic and biotic stress interactions on crop growth and yield formation and quality is non-additive and thus differs from the sum of individual stress impacts; (ii) while the mechanisms underlying the abiotic and biotic stress interactions are of universal validity, their impacts are modulated by certain environmental conditions (such as temperature, light conditions and soil properties).Realization and evaluation of such platform will allow consideration of interactions between abiotic and biotic stresses and hence improve the predictive skill of crop growth models.