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Agroscope, University of Zurich

Crop-Variety Mixtures for Greater Yields and Robustness

Nature Ecology & Evolution 5, 1068–1077, 2021.

Crop variety mixtures can have various benefits, including greater resistance to pathogens as well as yield stability and increased yields.

Higher genetic diversity in the field reduces the risk of pathogens spreading unchecked, since the individual varieties grown have different degrees of susceptibility. According to past experience, the cultivation of variety mixtures, particularly over a large area, has significant potential for reducing plant-protection product use.

In addition, mixtures open up new resistance-breeding possibilities. For example, they could be used to combine more resistance genes on a field instead of expending greater effort to combine them in an individual plant. This could simplify breeding and increase progress with other traits such as yield or quality.

Diversity means greater sustainability

More diversity in agricultural production can make an important contribution to sustainable intensification. Variety mixtures, e.g. of winter wheat, increase genetic diversity in the field and are compatible with mechanised cultivation. One of Agroscope’s aims is therefore to develop robust mixtures with market appeal. However, we lack efficient approaches for predicting suitable mixture partners. Developing high-yielding variety mixtures is thus a complex matter, demanding considerable time and effort. Efficient methods for selecting mixture partners that maximise the value-added of variety mixtures are essential.

Forwards into the future with new concepts

For variety mixtures to work, the differences in key agronomic traits of the mixture partners must remain minor in order to prevent production and sales issues. At the same time, the individual mixture partners must be ‘specialised’ and complement one another, e.g. through differences in soil-nutrient uptake or in terms of their tolerance of biotic or abiotic stress (drought, etc.). Such so-called ‘niche differences’ are expressed inter alia in differences in yield from site to site or year to year. Determining niche differences from variety-testing trials could thus be a game-changer for achieving variety mixtures with greater stability and higher yields. This concept is now to be tested in experiments. Furthermore, the acquired theoretical knowledge is to be increasingly used in practice. In this way, Agroscope hopes to help ensure the more-frequent use of variety mixtures in the future.

Conclusions

  • Differences in key agronomic traits of the mixture partners must remain minor in order to prevent production and sales issues.
  • The many ways of combining different varieties in mixtures makes it harder to research, develop and test mixtures. Recently developed methods for determining ideal mixture partners reduce the scope of the problem.
  • A successful mixture offers “more than the sum of its individual varieties”.
  • Mixtures open up new resistance-breeding possibilities. Thus, they could be used e.g. to combine more resistance genes on a field instead of expending greater effort to combine them in an individual plant. This could simplify breeding and increase progress with other traits such as yield or quality.
  • Variety mixtures with market appeal lead to resistance to pathogens as well as yield stability and increased yield.

Scientific article

Crop-Variety Mixtures for Greater Yields and Robustness

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