Fast estimation of chlorophyll content on plant leaves using the light sensor of a smartphone

摘要

Plant chlorophyll measurements can support nitrogen fertilization decisions. Using a 3D printed device and a red LED, here we tested the feasibility of using a smartphone ambient light sensor (ALS) to estimate leaf chlorophyll by light transmission. Its performance was evaluated by comparing 30 leaf sorghum ( Sorghum bicolor (L.) Moench) transmission readings of the red LED (663 nm) obtained from the smartphone and a standard spectrometer, which showed a good coefficient of determination (r 2 = 0.9067). Additionally, a comparison between the ALS and a SPAD 502 TM (a commercial device for chlorophyll content estimation) was made with chrysanthemum ( Dendranthema grandiflora Tzvelev) leaves, obtaining a good correlation between both measurements. Light transmission was also measured in S. bicolor flag leaves from plants growing in the greenhouse under increasing nitrogen fertilization. A clear fit between leaf light transmission and plant height was also observed, suggesting a simple, smartphone based estimation of plant’s chlorophyll.