Predicting and Understanding Diversity Benefits of Variety Mixtures

• Applicants: Samira El Hanafi, Ph.D.; Professor Dr. Jochen Reif
• Subject Area: Plant Breeding and Plant Pathology ; Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 550871742

Agriculture faces enormous challenges: yields have to increase while fertilizer and pesticide inputs need to be reduced, and this in a time of increasing climatic uncertainty. Crop diversification is one of the few options that allows to address all of these challenges simultaneously. Traditionally, diversification is achieved "temporally" in the form of crop rotations. In contrast, the "spatial" diversification in the field, e.g. in the form of mixed crops, is less frequently applied because it often conflicts with mechanized practices. Variety mixtures offer an interesting middle ground between pure and mixed-species cultures, because they allow to increase within-field genetic and trait diversity, yet are similar to pure crops with respect to processing. However, it currently is not well understood how mixtures need to be assembled to optimize yield and ecological functioning. Here, we propose to investigate positive effects of diversity in variety mixtures of wheat, and to develop simple yet effective predictive methods for optimal mixture assembly. We will combine the expertise, ideas, and technological resources of five research teams and from molecular breeding, ecology, computer science, genetics to phenomics. In an international collaboration, we will study the mechanisms underlying variety mixture benefits - specifically yield and disease suppression - at different levels: (1) adopting niche-based approaches inspired by coexistence theory, (2) using deep phenotyping and related trait-based methods, (3) focusing on crop productivity by mixing components with different environmental optima, and (4) at the level of genes and gene-by-environment interactions. Hypothesis testing and model development will be supported by both large historic field data sets and new, systematically-designed field experiments. The project consists of several work packages (WP) that capitalize on a common platform of data and experiments, and advanced field phenotyping methodologies. The combination of resources, analytical methods, and synergistic expertise will allow us to master the scientific and logistic challenges of this project, and to address major unsolved ecological and agronomic questions. It is hoped that this ambitious project lies the cornerstone to promote high-performing variety mixtures as a key component of agro-ecological production.

• DFG Programme: Research Grants
• International Connection: Switzerland
• Cooperation Partners: Privatdozent Dr. Andreas Hund; Professor Dr. Pascal A. Niklaus; Professor Dr. Bruno Studer; Professor Dr. Achim Walter; Samuel Wuest, Ph.D.