Building the Whole-plant Phenotype: Coupling Geophysically-based
Below-ground Measurements with Above-ground Data
Abstract
Wheat is one of the most widely grown crops and it plays an important
role in food production. Currently there is considerable interest in
identifying traits that contribute to high yields. Trait selection has
mainly focused on the above-ground part of the plant neglecting
below-ground processes. Climate change and the greater uncertainty in
weather conditions challenge our current food system and create the need
to select more varieties with grater resilience against the effects of
climate variation. The root system of the plant plays a key part in this
resilience, but it is difficult to study at the field-scale which is
essential for the effective selection of breeding lines. Geophysical
tools such as electromagnetic induction (EMI) and electrical resistivity
tomography (ERT) offer the possibility to study the below-ground
phenotype of the plant in a non-destructive and high-throughput manner.
In this study, changes in soil moisture induced by root water uptake are
monitored using time-lapse ERT/EMI surveys. These methods were applied
at two scales: (a) at a high-spatial resolution where hundreds of wheat
varieties were monitored monthly using EMI in a wheat breeding field
trial and (b) at high-temporal resolution where hourly ERT measurements
were collected along with above-ground phenotyping traits on a few plots
with a field facility (Field Scanalyzer). Coupling these
geophysically-based below-ground data with above-ground canopy
measurements can increase our understanding of the crop response to its
environment. Good correlation was found between leaf area index (LAI)
and soil drying inferred from EMI measurements for the high-spatial
experiment (a). The ERT monitoring experiment (b) accurately showed the
dynamics of two different nitrogen treatments, their interactions with
weather conditions and their correlation with above-ground crop growth.
Coupling geophysically-based below-ground measurements with above-ground
data allows the increased understanding of the whole plant phenotype.
This might help to identify useful traits to select for increased crop
yield and resilience.