Sensing Botrytis cinerea in Tomato Using Visible/Near-Infrared (VIS/NIR) Spectroscopy

Abstract

Gray mold disease caused by Botrytis cinerea is considered one of the most common diseases that affect tomato fruits and cause economic losses; early detection of the disease can reduce 50% of the losses and increase food security. Therefore, this study aimed to employ the visible/near-infrared (VIS/NIR) spectroscopy to sense the presence of gray mold on tomato fruits in the early stages. Identify of B. cinerea was carried out using the polymerase chain reaction (PCR). In addition, 30 homogeneous tomato samples were collected from three different varieties, i.e. Harver, Izmer and Ekram, 20 samples from each variety were injected with the pathogen and 10 samples from each variety were left as a control and were measured using the VIS/NIR spectroscopy daily for five days. Spectral data acquired from the VIS/NIR spectroscopy, with a range of 550- 1100 nm, were analyzed using principal component analysis (PCA). It was found that the PCA on the second day after injection was able to distinguish 2 completely between infected and healthy samples before symptoms appeared, also two PCs for VIS/NIR region explained approximately 99% of the total variance in the third and fourth day. Moreover, two PCs explained 98% of the total variance for PCA that applied for the average of infected samples for all days. The PCA results showed the ability of VIS/NIR spectroscopy to detect latent infections in tomato fruits as well as the early sensing of B. cinerea. Furthermore, when observing the infected samples from these varieties to detect which are resistant to gray mold disease, it was found that all of these varieties were sensitive to the disease.