Pepper plants leaf spectral reflectance changes as a result of root rot damage

Symptoms of root stress are hard to detect using non‐invasive tools. This study reveals proof of concept for vegetation indicesʹ ability, usually used to sense canopy status, to detect root stress, and performance status. Pepper plants were grown under controlled greenhouse conditions under different potassium and salinity treatments. The plantsʹ spectral reflectance was measured on the last day of the experiment when more than half of the plants were already naturally infected by root disease. Vegetation indices were calculated for testing the capability to distinguish between healthy and root‐damaged plants using spectral measurements. While no visible symptoms were observed in the leaves, the vegetation indices and red‐edge position showed clear differences between the healthy and the root‐infected plants. These results were achieved after a growth period of 32 days, indicating the ability to monitor root damage at an early growing stage using leaf spectral reflectance.