Identification of species traits enhancing yield in wheat-faba bean intercropping: development and sensitivity analysis of a minimalist mixture model

Berghuijs, H.N.C.; Wang, Z.; Stomph, T.J.; Weih, M.; Werf, W. Van der; Vico, G.


Aim: Cereal-legume intercropping can result in yield gains compared to monocrops. We aim to identify the combination of crop traits and management practices that confer a yield advantage in strip intercropping. Methods: We developed a novel, parameter-sparse process-based crop growth model (Minimalist Mixture Model, M3) that can simulate strip intercrops under well-watered but nitrogen limited growth conditions. It was calibrated and validated for spring wheat (Triticum aestivum) and spring faba bean (Vicia faba) grown as monocrops and intercrops, and used to identify the most suitable trait combinations in these intercrops via sensitivity analyses. Results: The land equivalent ratio of intercrops was greater than one over a wide range of nitrogen fertilizer levels, but transgressive overyielding, with total yield in the intercrop greater than that of either sole crop, was only obtained at intermediate nitrogen applications. We ranked the local sensitivities of the individual yields of wheat and faba bean of the whole intercrop under various nitrogen input levels to various crop traits. Conclusions: The total intercrop yield can be improved by selecting specific traits related to phenology of both species, as well as light use efficiency of faba bean and, under high nitrogen applications, of wheat. Changes in height-related crop traits affected individual yields of species in intercrops but not the total intercrop yield.