Modeling the relationship between extractable chlorophyll and SPAD-502 readings for endangered plant species research

Summary ld chlorophyll meters have proven to be useful tools for rapid, non-destructive assessment of chlorophyll and nutrient status in various agricultural and arborescent plant species. We proposed that a SPAD-502 chlorophyll meter would provide valuable information when monitoring life cycle changes and intraspecific variation in endangered plant populations, whereby, destruction of plants to obtain this information is impractical. Further, use of this instrument would augment leaf morphometric measurements collected during controlled studies, circumventing the need for leaf harvest. We developed a regression model relating foliar chlorophyll concentration and content to SPAD chlorophyll content indices for a genetically diverse population of the federally listed Lindera melissifolia. Application of the regression to four additional L. melissifolia populations, and to the ecologically widespread congener L. benzoin, proved the SPAD-502 to be an effective tool for non-destructive estimation of total foliar chlorophyll concentration (r2=0.8230) and content (r2=0.9029) across a range of plant ages, growing conditions, and genotypes.