Quantitative analysis of root system architecture and fresh weight biomass traits highlight phenotypic variation in radish (Raphanus sativus L.) germplasm

Radish exhibits remarkable diversity in root morphology and architecture, which are crucial traits for nutrient and water uptake, stress adaptation and marketability. This study assessed root variability in 23 radish accessions, including a wild relative, landraces, and cultivars. Plants were grown in controlled greenhouse, and 2D images of roots acquired, using a high-resolution flatbed scanner fitted with a transparent acrylic tray (30 cm × 20 cm). Root analysis was performed using the WinRHIZO Pro software (Regent Instruments Inc., Quebec, Canada). Results of the analysis of variance revealed significant genotype variation (p < 0.01) for nearly all traits, except average length of link. Turkish accessions recorded the longest average root length and greater root branching, whereas Chinese and Korean accessions exhibited significantly larger root diameters and higher root biomass-related trait values. Landraces developed the most extensive root systems, wild relatives showed high trait variability, and cultivars were more uniform in root volume and diameter. Correlation analysis revealed strong positive associations (p < 0.01) among root length, surface area, projected area, and branching, suggesting a coordinated system for soil exploration. Principal component analysis identified five functional clusters, explaining 93.485% of total variation. This study revealed the presence of a wide range of variation in radish root traits and provides a foundation for trait selection, targeting resource-use efficiency, and market needs.