Using clear plastic CD cases as low‐cost mini‐rhizotrons to phenotype root traits

PREMISE: We developed a novel low‐cost method to visually phenotype belowground structures in the plant rhizosphere. We devised the method introduced here to address the difficulties encountered growing plants in seed germination pouches for long‐term experiments and the high cost of other mini‐rhizotron alternatives. METHODS AND RESULTS: The method described here took inspiration from homemade ant farms commonly used as an educational tool in elementary schools. Using compact disc (CD) cases, we developed mini‐rhizotrons for use in the field and laboratory using the burclover Medicago lupulina. CONCLUSIONS: Our method combines the benefits of pots and germination pouches. In CD mini‐rhizotrons, plants grew significantly larger than in germination pouches, and unlike pots, it is possible to measure roots without destructive sampling. Our protocol is a cheaper, widely available alternative to more destructive methods, which could facilitate the study of belowground phenotypes and processes by scientists with fewer resources.