Yield, Quality and Stability: Wheat Variety Mixtures Have Potential

A study conducted by Agroscope in collaboration with IP-Suisse, DSP and FFB-Group shows that wheat variety mixtures generally perform better and are more stable than varieties grown in pure stands. Recommendations are made for practical applications.  

In the ongoing quest for a more efficient, more sustainable and more resilient agricultural sector, variety mixtures are often put forward as an option for improving crop stability. Although the effects of mixtures on yield have been researched, not much is known about the mechanisms in play, the impact of mixtures on quality, or the optimal combinations of varieties. It is to answer these questions that Agroscope, IP-Suisse, DSP and FFB-Group tested wheat variety mixtures over several years and at several sites, and assessed different parameters associated with seed yield and quality.

The study was conducted from 2020 to 2023 with eight wheat varieties sown either in pure stands, in all possible mixtures of two varieties, or in mixtures of eight varieties. The trial was repeated at three sites in Switzerland during the three growing seasons to assess the stability of the mixtures and the pure stands. The research teams measured seed yield and parameters associated with seed quality, namely protein content, thousand-kernel weight, hectolitre weight and Zeleny sedimentation value.

Mixtures generally exhibited higher performance and stability than monocultures

In general, when combining all parameters, the mixtures proved to be more productive and stable over the years and across the sites than the monocultures – a surprising and positive result, considering that the trials did not specifically focus on chosen mixtures.

The Zeleny value of the mixtures was higher than that of the monocultures. This result is relatively new and of interest for the sector, since it suggests that the mixtures could potentially lead to better breadmaking quality.

Agroscope scientists have also studied the link between the performance and stability of these parameters and the characteristics of the pure-stand varieties. They discovered that in general, the best mixtures were those combining varieties of similar height and phenology, but with different yields when grown in pure stands.  

Moreover, the mixtures were more productive when the combined varieties were able to intercept more light than the pure stands.

No single solution

Although the variety mixtures turned out more successful overall than the monocultures, this was not always the case when considering each parameter individually. For example, in the study, the Zeleny value was higher in the mixtures, but for yield, thousand-kernel weight or hectolitre weight the difference between mixtures and monocultures was not significant. Protein content was in fact even lower. This shows that there is no ‘one size fits all’ solution and highlights the importance of applied research for advances in agriculture.