Abstract:
The potential exists to breed for root system architectures that optimize resource acquisition. However, this requires
the ability to screen root system development quantitatively, with high resolution, in as natural an environment as
possible, with high throughput. This paper describes the construction of a low-cost, high-resolution root phenotyping platform, requiring no sophisticated equipment and adaptable to most laboratory and glasshouse environments,
and its application to quantify environmental and temporal variation in root traits between genotypes of Brassica rapa
L. Plants were supplied with a complete nutrient solution through the wick of a germination paper. Images of root
systems were acquired without manual intervention, over extended periods, using multiple scanners controlled by
customized software. Mixed-effects models were used to describe the sources of variation in root traits contributing to root system architecture estimated from digital images. It was calculated that between one and 43 replicates
would be required to detect a significant difference (95% CI 50% difference between traits). Broad-sense heritability
was highest for shoot biomass traits (>0.60), intermediate (0.25–0.60) for the length and diameter of primary roots and
lateral root branching density on the primary root, and lower (<0.25) for other root traits. Models demonstrate that root
traits show temporal variations of various types. The phenotyping platform described here can be used to quantify
environmental and temporal variation in traits contributing to root system architecture in B. rapa and can be extended
to screen the large populations required for breeding for efficient resource acquisition
