Phenotypic variability and modelling of root structure of wild Lupinus angustifolius genotypes

Root plasticity in response to the edaphic environment represents a challenge in the quantification of phenotypic variation in crop germplasm. The aim of this study was to use various growth systems to assess phenotypic variation among wild genotypes of Lupinus angustifolius. Ten wild genotypes of L. angustifolius selected from an earlier phenotyping study were grown in three different growth systems: semi-hydroponics, potting-mix filled pots, and river-sand filled pots. Major root-trait data collected in the present study in the semi-hydroponic growth system were strongly correlated with those from the earlier large phenotyping trial. Plants grown in the two solid media had some of the measured parameters significantly correlated. Principal component analysis captured the major variability in three (semi-hydroponics) or four (solid media) principal components. The genotypes were grouped into five clusters for each growth media, but cluster composition varied among the media. We found genetic variation and phenotypic plasticity in some root traits among tested genotypes. Using input parameters derived from the semihydroponic phenotyping system, simulation models (ROOTMAP and SimRoot) closely reproduced the root systems of a diverse range of lupin genotypes. Wild L. angustifolius genotypes displayed genetic variation and phenotypic plasticity when exposed to various growth conditions. The consistent ranking of genotypes in the semihydroponic phenotyping system and the two solid media confirmed the capacity of the semihydroponic phenotyping system of providing simple and relevant growing conditions. The results demonstrated the utility of this system in gathering the data for parameterising the simulation models of root architecture.