Detection of Anthracnose Disease in ‘Namdokmai Sithong’ Mango Using Near Infrared Spectroscopy

Abstract

The aim of this research was to detect anthracnose disease in ‘Namdokmai Sithong’ mango fruit using near infrared spectroscopy (NIRS). Inoculation using 20 µL of 10⁶ spores/mL Colletotrichum gloeosporioides spore suspension was done onto mango fruit’s peel (one cheek; accounted as infected) while another cheek was left intact (accounted as control). The inoculation was conducted using 102 mango fruits prior to incubating the samples in moist chambers (100 % relative humidity). The chambers were thereafter stored at 28 ^ºC for 24 h before acquiring NIR spectra from both fruit cheeks using FT-NIR apparatus. The spectra were divided into training and testing sets (each set consisted of 102 spectra: 51 intact and 51 infected) before performing a partial least squares discriminant analysis (PLS-DA). The results indicated that spectra preprocessed by standard normal variate (SNV) method could discriminate anthracnose-infected against intact mango fruit with an overall classification accuracy of 95.1 %. Wavelengths of 1152, 1725, and 1880 nm were important to the classification model. In summary, NIRS with PLS-DA could be a possible tool for detecting anthracnose disease in mango.