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2. Methodology 2.1. Study area and sample size The test was carried out under greenhouse conditions at the facilities of the Association of Banana Growers of Colombia in the Carepa municipality (Antioquia, Colombia). Banana plants var. Gros Michel and Williams were propagated in vitro in a commercial nursery. A completely randomized experimental design with four treatments and their respective controls was carried out on the following spects:1) 30 control plants var. Gros Michel, 2) 30 plants var. Gros Michel inoculated with R. solanacearum, 3) 30 plants var. Gros Michel subjected to hydricstress, 4) 30 control plants var. Williams, 5) 30 plants var. Williams inoculated with R. solanacearum, and 6) 30 plants var. Williams under hydricstress. Treatments were started with three-month old plants at the phenological stage 1030 of the BBCH scale (REF). The plants were planted in bags with a capacity of 2 kg of peat. The internal environmental conditions in the greenhouse during the experimentation time were under the following conditions: XXX °C average temperature and XXX% relative humidity. The plants were watered three times weekly. 2.2. Microorganisms used and inoculation of plants The National Banana Research Center (CENIBANANO) provided a strain of R. solanacearum Race 2 for the research. The pathogenicity of this strain was determined using the Gros Michel and Williams clones previously referenced (Ramírez et al. 2020) and the described protocols for pathogenicity tests in this pathosystem (Obregón et al. 2008). The strains were seeded in semi-selective XXX media and grown under constant agitation for 24 h. The inoculum concentration was estimated using spectrophotometry, using as a reference a 1x108 cfu/ml-1 solution with an optical density of +0.1 at 650 nm. The plant infections were based on the Jie et al. (2009) methodology. This involves making immersion cuts at the root base of each plant inoculum with a cutting scalpel and inoculating the substrate with 15 mL of a previously arranged inoculum suspension. 2.3. Data Analysis and Spectroscopy Reflectance spectra were obtained with a USB2000+ portable spectroscope (Ocean Optics, FL, USA) in a spectral range between 400-1100 nm, in which different parameters necessary for calibration were determined according to the Marín et al. (2021) protocol. At 48-hour intervals during the disease incubation period, three pseudo-repeats were collected from the top of the leaves of each of the three plants. The entire study period yielded a total of 900 spectra for each sampling day, and spectral measurements were taken on the plants subjected to the four treatments and their respective controls. The spectra medium for all treatments and controls were performed every 4 days from the inoculation day until symptoms were expressed to visualize differences in the reflectance spectra. Using the RELIEF characteristics classification algorithm, we identified specific wavelengths that would allow us to classify healthy plants infected with R. solanacearum and subjected to hydricstress. This scanning was complemented with a principal analysis component to identify which of the variables presented the greatest contribution to the total variation of the data during the entire disease incubation period classified with the RELIEF algorithm. Linear discriminant analyses were performed per sampling day as a supervising classification method of qualitative variables and observational classifications a priori into three banana variety groups analyzed (Gros Michel and Williams): plants inoculated with R. solanacearum, plants subjected to hydricstress, and healthy plants. Performing analyses were made with R v.4.0.5 software (RStudio Team, Boston, MA, USA).