Authors:

James D. Burridge, Harini Rangarajan, Jonathan P. Lynch

Source:

Crop Science, 60:2574–2593

Download options:

Crop Science website

Abstract:

Suboptimal water and phosphorus availability are primary limitations to grain legume production. Root architecture influences water and phosphorus acquisition but tradeoffs need to be better understood and mitigated. We hypothesized that tradeoffs in root class investment and resource acquisition strategy would be observable in a variety of grain legumes. Diversity panels of common bean (Phaseolus vulgaris), tepary bean (Phaseolus acutifolius), cowpea (Vigna unguiculata), soybean (Glycine max), chickpea (Cicer arientinum), groundnut (Arachis hypogaea) and single accessions of other legumes were phenotyped in the field. We identified inverse relationships among investments in different root classes in most species, and between indicators of deep and shallow exploration in all species. Bean and tepary bean showed particularly strong tradeoffs in investment patterns among root classes, while chickpea and groundnut show less pronounced tradeoffs. We found that legume root architectural phenotypes can be placed on a root system architecture (RSA) spectrum and that root phenotypes of epigeal and hypogeal taxa present distinct adaptive mechanisms. These life strategies integrating resource acquisition, use and phenology are exemplified by contrasting chickpea, with many root axes, to tepary bean with few root axes and a contrasting water use strategy. We propose several RSA ideotypes and highlight how dimorphic root architecture may co-optimize resource acquisition.