Performance of a winter wheat composite cross population in two temperate agroforestry systems: a case study

In agroforestry systems (AFS), where environmental conditions are highly variable at small spatial scales, the use of uniform genetic material of a single cultivar commonly grown in monoculture cropping might not be optimal. However, the use of composite cross populations (CCPs) that contain an inherent genetic variability might be a promising approach to match the environmental variability created by trees in AFS. In this experimental trial, the performance of a CCP ("CC-2k") of winter wheat was compared to a commercial variety ("Wiwa") in a split-plot design in two AFS (Feusisberg, Wollerau) in Central Switzerland. The factor variety (p < 0.05) and the interactions of site and distance to tree (p < 0.05) and site and variety (p < 0.05) significantly affected wheat yield at the plot level. CC-2k and Wiwa yield (across all distances) amounted to 1.9 +/- 0.7 Mg ha-1 and 2.0 +/- 0.8 Mg-1, respectively, in Feusisberg and to 1.9 +/- 0.9 Mg ha-1 and 0.7 +/- 0.4 Mg ha-1, respectively, in Wollerau. Wiwa had a higher protein, Fe and Ca content than CC-2k. Therefore, while the CC-2k outperformed the commercial organic variety Wiwa in terms of yield in one of the two AFS, Wiwa outperformed CC-2k in terms of quality. The composite cross population might be better adapted to the heterogenous environment of agroforestry systems but fails to reach the high-quality product of modern elite cultivars. Further improvements in terms of quality might make CCPs highly interesting for diversified agricultural systems with larger environmental heterogeneity than common monoculture cropping systems. ### Competing Interest Statement The authors have declared no competing interest.