Speaker
Description
Introduction
In the face of climate change, improving the stability of food production systems is critical. Increasing diversity in agricultural fields can be a way to stabilize production across time and/or space. Variety mixtures represent a practical way to introduce diversity at the genotype level (Kopp, 2023). In Switzerland, variety mixtures remain rarely used, due to uncertainties and lack of understanding of the processes driving potential benefits for productivity, quality, and stability. This research presents results from a multi-year, multi-site wheat variety mixture experiment investigating the role of variety mixtures to increase crop performance and stability, and the mechanisms underlying these effects.
Methods
The experimental design included 8 Swiss wheat varieties in a diallel design (i.e. all varieties in pure stand and all 2-variety mixtures) and one mixture combining the 8 varieties. The experiment was replicated three times with a full randomized block design. We set up the field trials in three Swiss sites varying in environmental conditions, during three years (from 2021 to 2023). We measured a variety of agronomic parameters, such as yield, protein content, thousand kernel weight, hectolitre weight, Zeleny, but also functional traits during the growing season, for instance height, heading date, specific leaf area, etc. Crop performance and stability was assessed using Weighted Average of Absolute Scores as well as Multi-trait Stability Index as described by Olivoto et al. (2019). We examined links between mixture performance, stability, and characteristics of the varieties composing the mixtures with linear regressions, as described in Stefan et al. (2023). We hypothesized that mixtures composed of more different varieties – in terms of genetic distance but also morphological, agronomic, or synchronicity aspects – would be more performant and/or stable.
Results
Mixtures generally had a positive effect on yield, but not on protein content. Unlike what is commonly assumed, results of the multitrait stability index do not show that variety mixtures universally increase stability (Fig. 1). The 6 most stable plots include 3 varieties in pure stands, and 3 mixtures (2 of them including the most stable variety). Regarding traits or mechanisms explaining crop performance and stability, preliminary results indicate that (1) asynchrony of the components is positively linked to temporal and spatial yield stability, as already shown by Stefan et al. (2023), (2) the mean performance and stability of mixture yield is negatively correlated with the monoculture difference in specific leaf area (mixtures are more yield-performant when combining varieties with similar specific leaf area) and (3) multitrait stability is better when combining varieties with a high difference in phenology.
Discussion
This study investigates the links between performance and stability of wheat variety mixtures and various traits of the mixture components. It uses a multicriteria approach to evaluate crop performance and stability, by including agronomic parameters (such a yield, thousand kernel weight) but also quality parameters (protein content, zeleny sedimentation rate). Therefore, it allows to not only look at productivity, but also at the quality of the grains produced, and the stability of this quality. The complexity of the multivariate responses and explanatory variables requires more in-depth investigation; however, we can already state that our study confirms the defining role of asynchrony in driving yield stability, showing that combining less synchronous varieties (in terms of yield) can act as an insurance to environmental variability. This supports the role of variety mixtures as a promising solution to sustainably increase the stability of wheat production in Europe.
References:
Kopp, E. B., Niklaus, P. A., &Wuest, S. E. (2023). Ecological principles to guide the development of crop variety mixtures. Journal of Plant Ecology, 16(6).
Olivoto, T., A.D.C. L\'ucio, J.A.G. da silva, B.G. Sari, and M.I. Diel. 2019. Mean performance and stability in multi-environment trials II: Selection based on multiple traits. Agron. J. 111:2961-2969.
Stefan, L., Fossati, D., Camp, K.-H., Pellet, D., Foiada, F., & Levy, L. (2023). Asynchrony is more important than genetic distance in driving yield stability in wheat variety mixtures. Crop Science, 1–15.
| Keywords | variety mixtures ; diversification ; yield stability ; sustainability |
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