Questioning Seeding Rates and its Influence on Phenotypic Expression of Wheat Populations for Participatory Plant Breeding—First Findings from Field Research across Organic Farms in Belgium and the Netherlands

In Belgium and The Netherlands, bread wheat ( Triticum aestivum L.) is getting attention within a growing movement looking for more sustainability of wheat cropping and breadmaking. The few varieties available are pure lines that do not match the wide range of environments and organic farming practices, so that yields and milling quality are often disappointing. Composite Cross Populations (CCP) have been created with the idea of evolutionary plant breeding through on-farm mass selection and seed saving. In 2015–2016, one such CCP of winter wheat was cropped side by side with a pure line variety in four organic farms with different wheat cropping practices, as a first step to answer some of the concerns arising from farmers’ networks we work with. Seeding rates ranged from the standard high to the very low ones practiced under the System of Wheat Intensification (SWI). Multivariate data analysis confirmed greater differentiation of the CCP both compared with pure line varieties and within populations on farms where inter-plant competition was less intense. Low seeding rates thus seem to enhance the phenotypic expression potential of a CCP, yet this is a neglected fact among participatory plant breeders. Since both CCP and SWI have great potential for ecological intensification within organic farming, we argue that more work is needed on finding new ways of combining innovation in farming practices and on-farm plant breeding, which also implies new ways of organising research.