A new study published in Frontiers in Plant Science has highlighted the challenges of selecting foxtail millet varieties for dryland farming environments where growing conditions vary significantly between seasons.

Researchers from agricultural institutions in China investigated how different foxtail millet genotypes respond to environmental conditions across locations and years.

The research, led by Haiwang Yue and colleagues, examined grain yield adaptation using field trials conducted at 20 locations in northern China during the 2023 and 2024 growing seasons.

To compare performance across years, the researchers analysed 13 common genotypes across 40 location-year combinations, representing 1,560 plot observations.

The study focused on genotype-by-environment interactions, which describe how crop varieties respond differently depending on growing conditions.

The researchers found that interactions involving genotype, location and year accounted for 50.3% of the genotype-related variance examined.

Interactions between genotype and location accounted for 34.6%, while genotype-by-year interactions contributed 15.1%.

These results indicate that crop performance was influenced not only by geographical location but also by conditions specific to individual growing seasons.

A particularly important finding was the limited consistency in genotype responses between years.

The average genetic correlation between the same locations evaluated in different years was only 0.027, suggesting that the relative performance of different foxtail millet varieties often changed substantially between seasons.

At 12 of the 20 locations, the researchers found negative correlations between genotype responses across the two years.

The study also examined whether long-term climate patterns, soil properties and seasonal weather anomalies could explain these differences.

Although the researchers identified substantial environmental variation, the measured factors showed only weak relationships with the underlying patterns of genotype responses.

Interestingly, the overall rankings of broadly performing genotypes were relatively stable, even though individual varieties differed considerably in their responses to particular environments.

This distinction is important for crop breeding.

A variety that performs consistently well across many environments may be easier to identify than one that is reliably superior in a particular location every year.

The researchers concluded that testing varieties at a location for only one season may provide insufficient information for making reliable location-specific breeding recommendations.

Instead, they emphasised the importance of multi-year field trials and testing networks that represent a wide range of environmental conditions.

For millet breeding programmes, these findings offer evidence that seasonal variability should be considered alongside geographical differences when evaluating new varieties.

The research could help inform more reliable approaches to foxtail millet selection for dryland farming systems, where variable rainfall and environmental conditions present continuing challenges.

However, the findings are based on a two-year trial network in northern China and should not automatically be generalised to all foxtail millet-growing regions without further testing.