Combining Genetic Gain and Diversity in Plant Breeding: Heritability of Root Selection in Wheat Populations

Abstract

To increase the resilience of agroecological farming systems against weeds, pests, and pathogens, evolutionary breeding of diversified crop populations is highly promising. A fundamental challenge in population breeding is to combine effective selection and breeding progress while maintaining intraspecific diversity. A hydroponic system was tested for its suitability to non-destructively select root traits on a population level in order to achieve genetic gain and maintain diversity. Forty wheat progenies were selected for long seminal root length (SRL) and 40 for short SRL from a wheat composite cross population grown in a hydroponic system. Wheat progenies were multiplied, and a subset evaluated again in a hydroponic system. Preliminary tests in soil and competition experiments with a model weed were performed. The hydroponic selection for long SRL led to an increase of SRL by 1.6 cm (11.6%) in a single generation. Heritability for selection of SRL was 0.59. Selecting for short SRL had no effect. The preliminary soil-based test confirmed increased shoot length but not increased SRL. Preliminary competition experiments point to slightly improved competitive response of wheat progenies but no improved competitive effect on mustard. These results indicate a heritable selection effect for SRL on a population level, combining genetic gain and intraspecific diversity.

Harnessing the Potential of Wheat-Pea Species Mixtures: Evaluation of Multifunctional Performance and Wheat Diversity

“…Likely, the phenology of the mid-early Kolompos, relative to the set of evaluated entries, is complementary to the pea cultivar "Fresnel" contributing to (temporal) niche differentiation and, thus, reduced competition. Interestingly, "Kolompos" also had the longest seminal roots in a recent hydroponic study, even longer than those of wheat plants selected specifically for long roots (Timaeus et al, 2021). As noted before, in our experiment, mixture effects are due to species mixing and density effects in an absolute sense, but comparing different entries in the same experimental setup still enables some insights.…”

Supply Chain Perspectives on Breeding for Legume–Cereal Intercrops

“…Aboveground traits include plant morphology, physiology, phenology, and developmental trajectories ( Lithourgidis et al, 2011 ; Isaacs et al, 2016 ; Saxena et al, 2018 ; Bourke et al, 2021 ; Nelson et al, 2021 ). Belowground traits (summarized in Homulle et al, 2021 ) include rooting patterns and architecture ( Lithourgidis et al, 2011 ; Streit et al, 2019 ; Bourke et al, 2021 ; Timaeus et al, 2021 ), nutrient-releasing or pathogen-suppressive root exudates, and associations with beneficial microbes including common mycorrhizal networks ( Barto et al, 2012 ; Brooker et al, 2015 ; Bourke et al, 2021 ). A positive effect of increased plant diversity on soil communities and plant microbiomes ( Strecker et al, 2015 ; Tiemann et al, 2015 ; Saleem et al, 2020 ) can act as a driver for the diversity–productivity relationship ( Raynaud et al, 2021 ).…”