Geo-informatics Techniques for Assessing Physiological Status and Productivity of RRIC 121 Genotype of Hevea brasiliensis (Rubber) under Different Harvesting Systems
Rubber (Hevea brasiliensis) one of the main plantation crops in Sri Lanka is the only
plant species cultivated commercially for natural rubber harvesting. Novel systems for
harvesting have been introduced but spatial distribution of photosynthetic potential
determining key factor for sustainable cultivation has not been properly explored. Use of such
techniques such as Satellite Remote Sensing (RS) and Geographic Information System (GIS)
to analyse spatial and biological factors related to the productivity of rubber plantation with
different harvesting systems is the main objective of the present study.
Quikebird high resolution satellite images were used for RS analysis. Chlorophyll
content of rubber leaves was measured using a SPAD-502 chlorophyll meter. Chlorophyll
content and satellite images were analysed using GIS and spatial statistical methods to
determine the variation in different harvesting systems. Yield data were collected from the
study site and yield parameters were correlated with chlorophyll content and Normalized
Difference Vegetation Index (NDVI) values. Results revealed all systems exhibited
promising yield performance without significant deviation but slightly higher yield per
hectare per year (YPH) and dry rubber content of latex (DRC) were recorded in quarter spiral
based once in three days (S/3 d4) and weekly (S/2 d1 2d7) harvesting systems. Chlorophyll
content and rubber yield showed direct correlation in all systems. NDVI vs chlorophyll
showed positive correlation r2=0.65 and spatial distribution of chlorophyll and NDVI values
demonstrated sound physiological status of plants across the plantation with different
harvesting systems. Cost effective LIH systems showed better production trend
demonstrating relatively higher yield while reducing tapping cost and labour. Satellite based
remote sensing technique is an easy and efficient tool to estimate productivity of rubber
plantation over a large area.
Keywords: Chlorophyll, NDVI, harvesting, Remote Sensing, Rubber.
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Journal of Tropical Forestry and Environment,
University of Sri Jayewardenepura, Nugegoda, Sri Lanka