Root Architecture Variation in Wheat and Barley Cultivars

Abstract

Aims: We analyzed root architecture variation among heirloom and commercial cultivars of wheat and barley to improve our understanding of the quantitative variation present within small grain root architectures. We also compared lab-based root architecture measures with cultivar shoot:root ratios and field data. Study Design: This study had a completely randomized design (CRD) with five replications of 5 heirloom and 4 commercial genotypes. Place and Duration of Study: The study was conducted in Plant Science Laboratory, Faculty of Land and Food Systems, The University of British Columbia, Canada, during May-June, 2012. Methodology: Wheat and barley seeds were grown on specific germination paper in a controlled environment, and were assessed for root architecture parameters: total root length, surface area, average diameter, root volume, number of tips, and branching angle (WinRHIZO Pro 2009c, Regent Instruments Inc.). Fisher’s least significant differences were calculated in MSTAT-C to assess genotypic variation of these parameters. We also calculated shoot:root ratios. These root architecture results were compared to parameters measured in the field for these cultivars. Results: Differences between wheat genotypes were identified among the cultivars with heirloom cultivars developing relatively larger and deeper root systems compared to the commercial cultivars (i.e., longer and thinner roots, more surface area, higher number of tips, and greater branching angle). Commercial wheat cultivars showed coarser roots (i.e., greater root diameters), more root volume, higher dry weight, and shoot to root ratios compared to the heirloom cultivars with cv. ‘Scarlet’ showing the highest values. Among barley cultivars, heirloom ‘Jet’ had the highest values for parameters (i.e., length, area, volume, and branching angle) and the lowest shoot:root ratio compared to the commercial cvs. ‘Oxbridge’ and ‘Camus’. The commercial wheat cv. ‘Scarlet’ showed a positive association between grain yield, under low input organic conditions, and root diameter whereas the heirloom barley cv. ‘Jet’ had positive associations between grain yield, root length and surface area. Conclusion: The root architectures of the heirloom wheat and barley cultivars indicate they may be better suited for low phosphorus and/or drought conditions, typical of low input or organic production. The root architectures of the commercial cultivars, on the other hand, were deemed more suitable for high input conditions. There exists a positive association between root length, surface and yield potential when heirloom wheat cultivars were grown under low input conditions. Longer and finer roots, and the lower shoot:root ratio in some heirloom cultivars further suggest breeding potential for improved nutrient uptake efficiency and drought tolerance in wheat and barley