2019 ASHS Annual Conference

In 2014, Parry et al. (In situ measurement of leaf chlorophyll concentration: analysis of the optical/absolute relationship; Plant, Cell and Environment) quantified the relationship between optical measurement of relative leaf chlorophyll with a handheld meter (Apogee Instruments model MC-100) and absolute leaf chlorophyll concentration determined by chemical extraction for twenty-two species. While there was some variability among species, Parry et al. derived a generic relationship relating leaf chlorophyll concentration to the relative optical measurement from the MC-100. This generic relationship can be used to reliably estimate leaf chlorophyll concentration for many species from in situ measurements with the MC-100. Using the methods detailed in Parry et al., the relationship between absolute leaf chlorophyll concentration and the relative optical measurement from the MC-100 was derived for Vitis vinifera and Cannabis sativa, two high value crops that were not included in the study by Parry et al. Data for Vitis vinifera indicate a close match to the generic relationship derived by Parry et al., but data for Cannabis sativa indicate less chlorophyll per unit of leaf area for a given optical measurement when compared to the generic relationship. This suggests Cannabis sativa leaves absorb more photosynthetic radiation with less leaf chlorophyll than any of the species measured by Parry et al., and also suggests the unique equation derived for Cannabis sativa should be used to provide accurate in situ leaf chlorophyll concentration estimates using the MC-100.