Ecology & Safety, Volume 15, 2021

Abstract: We assessed the predictive capability of the optical meter for determining leaf pigment status of Quercus mongolica, Betula platyphylla, Phellodendron amurense, Juglans mandshurica, Fraxinus mandshurica, Acer mono, Tilia amurensis, and Ulmus propinqua during the growing season. The relationships between extractable Chl (a+b) concentration per unit of leaf area/content per unit of fresh leaf mass and the SPAD values generally followed a nonlinear function, and variations in the calibration line slope were markedly evident for eight tree species across sampling dates. Moreover, the relationships between the SPAD values and the concentration of Chl (a+b) were stronger than content both within and across dates in all tree species in most cases. Even though R2 values between Chl (a+b) content and SPAD meter readings were improved by incorporating leaf mass area (LMA) and leaf water content (LWC) as the independent variables into regression compared with those values showed in simple regression equations of eight tree species, which the content of Chl (a+b) were significantly negatively correlated with LMA, and mostly positively with LWC. Overall, our results indicated that the optical meter can accurately estimate leaf pigment during the growing season-but that the accuracy of the estimate varies across species throughout development. Precautions for using the meter are prescribed if unhealthy leaves are to be measured.