Correspondence: j.fernandez@uq.edu.au

To assist growers and industry in varietal decision-making, variety performance trials are conducted to evaluate the yielding ability of commercially available cultivars across different growing conditions. With more than a hundred wheat (Triticum aestivum L.) trials each year, the National Variety Trials (NVT) program in Australia encompasses diverse environmental conditions producing large genotype-by-environment (G×E) variability.

In this study, we aimed to classify the seasonal environmental patterns in NVT into few interpretable groups or environment types (ET) as a potential useful strategy for describing such G×E variability in Australia. We compared approaches for such classification that vary in which way the environmental information were taken into account: static or functional indices.

The former considers environmental effects via temporally static or aggregated data by phenological phases of the crop, while the latter combines functional environmental indices to capture the dynamic nature of G×E over the season via continuous time series data. When the resulting ET were included in mixed model analyses, both the ET and G×ET terms were consistently significant.

However, G×ET accounted for larger proportion of variance when ET were defined based on static indices. ET derived from this method were notoriously different in three main characteristics: water, nitrogen, and cold stresses. Across 2015 to 2021 wheat NVT, the most frequent environment type was associated with low water and nitrogen availability, while those with optimal conditions were considerably less frequent.

Our study provides insights into the value of incorporating advanced environmental characterisation techniques in the classification of Australian wheat variety trials. These findings can inform breeders, agronomists, and growers in tailoring strategies to address climate variability challenges and enhance wheat yield in diverse environmental conditions.