EXPLORING THE RELATIONSHIP BETWEEN REFLECTANCE RED EDGE AND CHLOROPHYLL CONCENTRATION IN SLASH PINE LEAVES

Chlorophyll concentration is related positively to the point of maximu m slope in the reflectance spectra of leaves and this point is termed the red edge. The reflectance spectra of slash pine (Pinus elliottii E ngelm,) needles were measured in the field and the chlorophyll concent rations of the same needles were measured in the laboratory, The measu rement errors for red edge and chlorophyll concentration were determin ed to be 2.2 nm (3% of mean) and 0.35 mg g(-1) (19% of mean), respecti vely. The red edge-chlorophyll concentration relationship was strong ( r(2) = 0.82, n = 152). A red edge-chlorophyll concentration relationsh ip for n = 100 was used with red edge measurements to estimate chlorop hyll concentration with an rms error of 0.31 mg g(-1) (17% of mean, n = 52), The entire red edge-chlorophyll concentration relationship for n = 152 was also used with red edge measurements to estimate the chlor ophyll concentration of samples from an earlier experiment with an rms error of 0.47 mg g(-1) (30% of mean, n = 38). We conclude that measur es of red edge can be used to estimate the chlorophyll concentration o f detached needles in the field with an accuracy similar to that obtai ned by conventional laboratory measurements.