2.1 Datasets
To validate our method we selected fifteen microscopy images of rice, maize and common bean roots taken at different root classes and grown under different treatments. All roots grew in a hydroponic system and were stained with toluidine blue before image acquisition. For each image, we counted and traced all individual root hairs to be used as a validation set. To demonstrate the usability of our method we used a dataset of three Thai inbred maize lines: Tak Fa 1, Tak Fa 2 and Tak Fa 3. For each genotype three to four replicates were grown in control, reduced nitrogen, reduced phosphorus, and reduced potassium conditions, respectively. For each replicate, five to seven images were taken along the root; for each image, five representative root hairs were traced manually to measure their length and root hair density was measured along a representative area of the root.