Feasibility of Using Near-Infrared Spectroscopy to Detect Spores of Anthracnose-Pathogenic Fungi in ‘Namdokmai Sithong’ Mango Fruit

Abstract

     This research aimed to detect spores of anthracnose-pathogenic fungi in ‘Namdokmai Sithong’ mango fruit using near-infrared spectroscopy (NIRS). A spore suspension of the fungus Colletotrichum spp. (10⁵ spores/mL) was tested for fungal infestation on the mango fruits. Twenty microliters of spore suspension were inoculated on the mango fruit peel. The sample was incubated in a moist chamber (100% relative humidity) at 28ºC. The results indicated that after 72 and 96 hours, the ‘Namdokmai Sithong’ mango fruit showed symptoms of anthracnose disease. The NIR spectra of Colletotrichum spp. spore suspensions were measured directly onto a fiberglass paper at a concentration of 10⁵ spores per milliliter. The NIR6500 spectrometer was used to measure NIR spectra data in reflectance mode over a wavelength of 400 and 2500 nm. The spectral data were analyzed using Principal Component Analysis (PCA) and Partial Least Squares (PLS) regression. The results indicated that NIRS could be used to detect spores of anthracnose-pathogenic fungi in ‘Namdokmai Sithong’ mango fruit. Moreover, the wavelengths at 1340 - 1344,  1725,  2300 - 2380, and 2400 - 2460 nm were identified as key spectral ranges for detecting spore suspensions. Therefore, using NIRS, it could be possible to detect spores of anthracnose pathogenic fungi in ‘Namdokmai Sithong’ mango fruit.