Envirotypes for wheat G×E in Australia: Integrating multiple environmental indices to characterise variety trials

The National Variety Trials (NVT) - the largest coordinated crop trial network in the world - is conducted each year to evaluate the yielding ability of commercial wheat cultivars in Australia. As the complexity of genotype-by-environment (G×E) interactions in these trials poses challenges for variety selection, envirotyping represents a promising way forward for more informed decision making. Here, we proposed to classify 800 NVTs into envirotypes and use those to model G×E as genotype-by-envirotype (G×ET) interaction. We compared approaches for such classification that varied in how phenotypic and environmental information are considered. The simplest approach was based on dimensionality reduction and clustering techniques using only static environmental indices - i.e., averaged by phenological period. The most complex method combines the inclusion of yield data for the selection of environmental traits and functional environmental indices to capture the dynamic nature of G×E over the season. Across methods, we found discrepancies in the defined envirotypes but consistency in the indices relevant for G×E variability. A substantial fraction of the G×E was captured by four defined envirotypes (18% across regions), offering a practical opportunity to leverage multi-environment yield and stress data to inform breeders, agronomists, and growers in variety recommendations. We discussed the need for an integration with multivariate Earth observations as way to anticipate envirotypes and support pre-season G×E predictions.