Characteristics of Virus Symptoms in Chili Plants (Capsicum frutescens) Based on RGB Image Analysis

Abstract

Virus infection in chili plants may cause various symptoms. The complexity of the symptoms and human vision ability often become limiting factors during disease investigations. Digital image analysis is expected to become a method to assist in comprehensively describing the symptoms of plant viruses. A disease survey was conducted on cayenne pepper fields in Southeast Sulawesi Province to observe symptoms of virus infection virtually and to record the symptomatic plant using an RGB camera. The split-channel method is used to process images, followed by multidimensional scaling statistical analysis. Later on, viruses associated with plants were detected serologically. Single or mixed infection of Tobacco mosaic virus, Cucumber mosaic virus, Chili veinal mottle virus, and Pepper mottle virus was confirmed by plant leaves showing yellow-mosaic and mottle symptoms. The digital image analysis method could show variations in the characteristics of symptoms based on digital numbers in that cannot be recognized based on the observation of visual symptoms. A new approach to study the interactions between plant infecting viruses and their effects based on image analysis has also been developed during this research. This method needs to be further validated through testing under controlled conditions, such as inoculating plants with a predetermined type of virus.

Vegetation index value on chili leaves with symptoms of geminivirus disease (case study in Konda district, Konawe Selatan regency, Southeast Sulawesi)

“…Fatigue when making observations, subjectivity in assessment [6], and expression of disease symptoms that are sometimes not visible due to environmental factors [7]. The complexity of symptoms due to interactions between viruses [5,8], the presence of DNA satellites that can affect the expression of symptoms [9], and the degree of plant resistance are some of the limiting factors in the application of visual observation-based assessment methods to the human eye.…”

Begomoviruses on two chili types in Southeast Sulawesi Indonesia: variation of symptom severity assessment and DNA-betasatellite identification

“…This bias is mainly caused by the subjectivity factor and variations in the evaluator's skill level, which often occur during visual observations. A previous study has reported that digital image processing can assess the severity of viral symptoms in the field (Hasan et al, 2022) and in experimental gardens (Hasan et al, 2021a).…”