Effect of Some Leaf Characteristics on Determination of Leaf Chlorophyll Content of Hevea brasiliensis with SPAD-502 Chlorophyll Meter
Chlorophyll meter SPAD-502 is widely used in determining leaf chlorophyll content in field
plants as it is non-destructive and less time consuming. Currently, there are about 25 Hevea
genotypes recommended by the Rubber Research Institute of Sri Lanka. Characteristics of
leaves, i.e., leaf thickness, wax and water content varies among the genotypes and also could
affect the readings of the SPAD-502 chlorophyll meter. Therefore, this study was carried out
to investigate effect of leaf thickness, wax and water content on determination of leaf
chlorophyll content of H. brasiliensis with SPAD-502 chlorophyll meter.
Most commonly grown Hevea genotypes i.e., RRIC 121, RRIC 100, RRISL 203 and RRISL
2001 were selected for the study. Leaf samples of each genotype were collected from the
budwood nurseries in Dartonfield Estate, Agalawatta. SPAD value of each leaf sample was
measured and subjected to analyse the actual chlorophyll content by acetone extraction
method. Leaf thickness, water content and epicuticular wax content of each leaf sample were
also measured by using standard test methods.
The highest leaf thickness, wax content and water content were observed in RRIC 100
genotype whilst RRISL 203 genotype gave the lowest values. Leaf chlorophyll content of
RRIC 121 genotype was comparatively lower with an average value of 36.51 μg/cm2.
However, the highest leaf chlorophyll content was observed in RRISL 203 genotype and the
average value was 54.28 μg/cm2. Despite the genotype average, leaf wax content and water
content were 79.75 μg/cm2 and 55.79%, respectively whilst leaf thickness was 0.126 mm.
Pearson correlation coefficients for leaf thickness, wax content and water content vs. reading
of SPAD-502 chlorophyll meter were above 0.05% and revealed that these three parameters
did not affect the reading of SPAD-502 chlorophyll meter significantly (p=0.05) in
determination of leaf chlorophyll content of H. brasiliensis.
Keywords: Chlorophyll, Epicuticular wax, Hevea, Leaf thickness
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Proceedings of International Forestry and Environment Symposium, Sri Lanka. Published by Department of Forestry and Environmental Science, University of Sri Jayewardenepura