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

Abstract

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 (r2 = 0.9067). Additionally, a comparison between the ALS and a SPAD 502TM (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.

Keywords

• Plant nutrition
• non-destructive chlorophyll meter
• leaf light transmittance