Exploring relationships between root architecture and growth of UK wheats
      (Triticum aestivum L.)
Creators: name: Hodgkinson, Laura
Publisher: name: Lancaster University
Year: 2017
Subjects: root penetration
Soil water availability
plant physiology
Root system architecture
Phenotyping

description: On Australian soils, where water is only available at depth during the
      grain filling period, growing deep rooting cultivars increased wheat
      yields by approximately 15%. Seedling root angle is associated with adult
      root system depth in Australian field-grown wheat cultivars (Triticum
      aestivum L.), but it is not yet known whether selection for root angle and
      rooting depth could benefit UK wheats. A soil-based, 3D, basket pot screen
      identified distinct root angle phenotypes (ranging from 35° to 52° from
      the vertical) among a selection of UK commercial cultivars. These
      phenotypes were generally stable despite varying soil water content, soil
      strength, and aerial temperature, but two cultivars showed significant
      changes in root angle in response to soil moisture. Cultivars Istabraq and
      Battalion displayed contrasting shallow and deep root angles,
      respectively. In fully factorial pot trials, with contrasting vertical
      soil moisture gradients and terminal drought treatments, genotype did not
      significantly affect early growth and physiology of young (tillering)
      wheat plants, but there were significant interactions with moisture
      gradient and water availability in some treatments. Under soil drying,
      ABA-mediated stomatal closure maintained Ψleaf in Battalion, whereas leaf
      decreased in Istabraq in the absence of changes in foliar ABA
      concentrations. This suggests contrasting water use strategies (isohydric
      Battalion and anisohydric Istabraq) are responsible for the observed
      physiological differences, rather than root angle. Field trials
      investigated whether these laboratory observations were correlated with
      root system development and yield of mature fieldgrown wheat. Soil cores
      taken from experimental wheat plots at Rothamsted Research’s Woburn farm
      were split at 10 cm intervals, and the number and positioning of roots and
      bio-pores at the exposed faces counted. Roots were washed from core
      sections to measure root length density by depth. Root length density
      declined with soil depth in all cultivars, and was not associated with
      seedling root angle phenotype, nor did yield correlate with root system
      traits. In the drier year only, Battalion had the most roots in the
      surface soil layers, which experienced greater soil drying under Battalion
      than under other cultivars. These studies contribute to the growing body
      of research on root system ideotypes in rainfed temperate climates, by
      identifying genetic variation in seminal root angle in high performing
      commercial wheat cultivars. While seedling root angle was not correlated
      with yield in field trials, it was associated with ability of roots to
      penetrate hard soils and access water in deeper strata of the soil
      profile. These traits would be especially beneficial during the
      grain-filling phase, and may potentially increase UK wheat yields during
      dry summers.