Tt. Lei et al., FUNCTIONAL-RELATIONSHIP BETWEEN CHLOROPHYLL CONTENT AND LEAF REFLECTANCE, AND LIGHT-CAPTURING EFFICIENCY OF JAPANESE FOREST SPECIES, Physiologia Plantarum, 96(3), 1996, pp. 411-418
We examined the functional relationship between chlorophyll concentrat
ions and light spectral absorption in 16 species of woody, vine and he
rbaceous plants in northern Japan. Leaves of each species from under f
orest shade and in more open sites were measured for chlorophyll, spec
ific leaf area (SLA) and spectral absorption. In all species, SLA incr
eased and the Chi a:b ratio declined in shade- vs open-grown leaves in
dicating an adaptive adjustment to forest shade in these leaf characte
rs. However, the expected increase in the ratio of 680 to 700 nm absor
ption in shade leaves did not occur in all species. Light absorption a
t 680 relative to 700 nm was lower in the shade leaves of Acer japonic
um, Kalopanax pictus, Panax japonicus and Petasites japonicus even wit
h a reduced Chi a:b, a commonly accepted indicator of shade adaptation
. Therefore, spectral measurements in these species failed to support
Chi concentrations that were expected to confer an improvement in the
absorption of red light (<680 nm) deficient relative to far-red light
(>700 nm) in the forest shade. Compared with other species, the absorp
tion pattern of these four 'non-conforming' species is associated with
a higher ratio of shade:open leaves in reflectance spectra in the 600
-750 nm range. This suggests an increased reflectance in shade leaves
caused by changes in leaf surface properties which are not immediately
apparent. We conclude that adaptive spectral absorption cannot always
be inferred from changes in specific leaf area and chlorophyll a and
b concentrations.