Phenotypic variability in bread wheat root systems at the early vegetative stage

P V Vara Prasad,Jairo Palta,Yinglong Chen,Kadambot H M Siddique

doi:10.1186/s12870-020-02390-8

Abstract

BackgroundUnderstanding root system morphology in bread wheat is critical for identifying root traits to breed cultivars with improved resource uptake and better adaptation to adverse environments. Variability in root morphological traits at early vegetative stages was examined among 184 bread wheat genotypes originating from 37 countries grown in a semi-hydroponic phenotyping system.ResultsAt the onset of tillering (Z2.1, 35 days after transplanting), plants had up to 42 cm in shoot height and 158 cm long in root depth. Phenotypic variation existed for both shoot and root traits, with a maximal 4.3-fold difference in total root length and 5-fold difference in root dry mass among the 184 genotypes. Of the 41 measured traits, 24 root traits and four shoot traits had larger coefficients of variation (CV ≥ 0.25). Strong positive correlations were identified for some key root traits (i.e., root mass, root length, and these parameters at different depths) and shoot traits (i.e., shoot mass and tiller number) (P ≤ 0.05). The selected 25 global traits (at whole-plant level) contributed to one of the five principal components (eigenvalues> 1) capturing 83.0% of the total variability across genotypes. Agglomerative hierarchical clustering analysis separated the 184 genotypes into four (at a rescaled distance of 15) or seven (at a rescaled distance of 10) major groups based on the same set of root traits. Strong relationships between performance traits (dry mass) with several functional traits such as specific root length, root length intensity and root tissue density suggest their linkage to plant growth and fitness strategies.ConclusionsLarge phenotypic variability in root system morphology in wheat genotypes was observed at the tillering stage using established semi-hydroponic phenotyping techniques. Phenotypic differences in and trait correlations among some interesting root traits may be considered for breeding wheat cultivars with efficient water acquisition and better adaptation to abiotic stress.

Highlights

Understanding root system morphology in bread wheat is critical for identifying root traits to breed cultivars with improved resource uptake and better adaptation to adverse environments
We aimed to characterize the phenotypic variability in root morphology in bread wheat in the selected
Phenotypic variation in early shoot and root growth At 35 days after transplanting (DAT), wheat plants were up to 42 cm tall (Fig. 1b) and the longest seminal roots up to 158 cm long (#73) with a root growth rate ranging from 1.2 cm (#119) to 4.4 cm per day (#73) (Table 1; mean data with standard errors for each genotype are not presented but available upon request)

Summary

Introduction

Understanding root system morphology in bread wheat is critical for identifying root traits to breed cultivars with improved resource uptake and better adaptation to adverse environments. Variability in root morphological traits at early vegetative stages was examined among 184 bread wheat genotypes originating from 37 countries grown in a semi-hydroponic phenotyping system. Efforts have been made to identify the constraints to crop growth and yield, with increasing interest in breeding wheat cultivars with suitable root. According to Violle et al (2007), performance traits contribute directly to fitness due to their effects on growth, reproduction and survival, while functional traits are. Some studies have evaluated phenology and morphological traits in large collections of wheat genetic resources [30, 31]. We aimed to characterize the phenotypic variability in root morphology in bread wheat in the selected Trait.

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