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

Johannes Timaeus,Odette Denise Weedon,Maria Renate Finckh

doi:10.3390/su132212778

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.

Highlights

There is a strong need for cultivars that are bred and optimized for agroecological and organic farming systems [1]
There was no significant correlation between thousand grain weight (TGW) and shoot length (SL) or seminal root length (SRL)
The significant increase of seminal root length (SRL) in a single generation indicates that non-destructive selection under hydroponic conditions for a vigorous root phenotype is possible and feasible

Summary

Introduction

There is a strong need for cultivars that are bred and optimized for agroecological and organic farming systems [1]. An increasing organic sector requires cultivars adapted to organic farming [2]. Homogeneous cropping systems can be vulnerable to abiotic stresses such as increased weather variability under climate changes found in a recent study for wheat cultivars [4]. Evolutionary breeding of composite cross populations (CCPs) has been developed to foster intraspecific diversity to enhance resilience against biotic and abiotic stresses that occur in organic and agroecologically managed farming systems [5,6,7]. Recent long-term studies provide robust evidence, by analyzing yield data for up to 13 years with stability indices, that CCPs are highly adaptive to environmental stress and provide higher yield stability than genetically homogeneous line cultivars in wheat [8,9,10].

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