Improvement of common bean root system phenotyping for identification of superior genotypes
The development of common bean plants with an improved root system can be a strategy for water and nutrient absorption in limiting environmental conditions. The objective of this study was to understand the influence of root phenotyping methods and phenological stages of evaluation on the selection of common bean genotypes for a highly branched root system. In the 2021/22 growing season, this study was initiated with 36 field treatments, consisting of the combination of three genotypes, two parents (Mesoamerican and Andean gene pools) and one progeny, two methods of root phenotyping (Shovelomics and WinRHIZO) and six growth stages (R1-6: four and eight trifoliate leaves, flower bud, full flowering, pod formation and grain filling). The field treatments were randomized in a simple lattice design. Five plants from each experimental unit were evaluated, considering the genotype and phenotyping methods in each developmental stage. The genotype x method x stage interaction was significant. The partitioning of the simple effects of the factors indicated that the root system variables of the parents could be distinguished from those of the progeny at R6. At this stage, the recommended phenotyping method differs according to the genetic origin of the genotypes. Plotting of the standardized canonical scores for the triple interaction showed that the Shovelomics and WinRHIZO phenotyping methods are adequate for the Andean and Mesoamerican genotypes, respectively, in view of their high scores with high discriminative power, allowing treatment discrimination. Specific phenotyping methods were indicated for Mesoamerican versus Andean genotypes in view of the root development trait intrinsic to each gene pool. We conclude that improving root phenotyping for the development of cultivars with a finely branched root system is a useful strategy to maintain common bean yields in environments under stressful conditions.