Baking quality of wheat organic heterogeneous material and variety mixtures: much more than flour blends

Summary

Despite taking up the highest share of utilized agricultural area in the EU (61%)1, arable crops are struggling the most to transition towards sustainable practices: while respectively 9.6 and 12% of permanent crops and permanent grassland area was organic, the share of organic arable land was only 5.8% in the EU-28 in 2018. Cereals – which are the main arable crops in Europe – are an eloquent example: in 2019, only 4% of the area cropped with cereals was organic in the EU. If the Farm to Fork Strategy’s objective of 25% of organic agricultural land by 2030 is to be achieved, the issue of organic transition in cereals should be of particular attention. In the case of bread wheat, a known agronomic lock-in is the lack of cultivars adapted to organic practices. Rigid DHS and VCU criteria which were designed for conventional breeding has long been one of the reasons for the gap in organic breeding. However, EU regulations have been adapted as of this year, and will introduce two major novelties: Organic Heterogeneous Material (OHM), which “is characterised by its high level of [intraspecific] phenotypic and genetic diversity, and its dynamic nature to evolve and adapt to certain growing conditions”, and a temporary experiment for Organic Varieties. Aside from the evolution capacity inherent to genetic diversity, a main interest of OHM is the facilitation effects that can result from crop intraspecific functional diversity. As such, OHM brings whole new challenges to breeders and researchers: to uncover the full potential of OHM, they need to gain a better understanding of the effects of diversity, in order to identify (un)favorable trait associations. Besides, variety mixtures are also reported to be gaining attention among farmers in France, reaching 17% of wheat stands in 2021, for which similar knowledge is required to guide efficient mixtures, thereby stressing the importance of these research questions. Besides agronomic considerations, this may also affect baking quality characteristics of OHM and mixtures, which warrants specific attention. Indeed, the baking quality of a mixture cannot simply be expected to correspond to that of a flour blend of the same constituting varieties: facilitation and/or competition between genotypes will be expected to affect the end-result. To address these questions, we have conducted agronomic trials in Gembloux, Belgium, evaluating mixtures of 2, 4 and 8 wheat varieties, as well as their constituting varieties grown in pure stands. Several agronomic observations where performed – including lodging resistance as well as relative yield and yield components of the different varieties within the mixtures –, along with baking quality indices such as protein content, test weight, Hagberg falling number and Zélény sedimentation test. In this presentation, we present preliminary results of these trials. To evaluate mixture performance, we compare baking quality performances of the mixtures to their estimation for flour blends of the same varieties. We then interpret these results in the light of our agronomic observations, in order to suggest hypotheses as to the possible mechanism underlying the observed mixture effects.