Estimating Wheat Root Biomass Using Ground Penetrating Radar.

In response to predicted climate change, crop scientists have increased their efforts to adapt crops to heat and drought stressed environments through breeding.  Increasing root biomass is one such trait; roots permit access to water at deeper soil profiles and aid in balancing evaporative demand at high vapor pressure deficit.  However, direct selection for roots is not yet feasible at a breeding scale due to the high cost and low throughput of current methodologies.  Ground penetrating radar (GPR) is a remote sensing technology that has been successfully used in evaluation of coarse tree root biomass.  Incorporating GPR into current crop phenotyping methodologies could potentially provide a long awaited solution to high throughput phenotyping for roots under realistic field conditions.  Here, the utility of using GPR to estimate root biomass of wheat was evaluated.  Using a Geophysical Survey System Incorporated SIR-20 GPR, a replicated field trial of spring wheat (Triticum spp.) genotypes with differing aboveground physiology, was agronomically evaluated then correlated with GPR returned signal.  Plants were grown in field breeding conditions under heat stress in vertisol type soils.  GPR profiles were collected at 40 cm intervals, using a signal frequency of 1.6 GHz.  Spatial variation within the trial was determined and considered using agronomic and GPR data.  Three-dimensional data reconstruction and analysis were rendered using GPR-SLICE v7.0 software.  An overview of issues and pitfalls in experimental design of GPR studies will be discussed.