Geo-informatics Techniques for Assessing Physiological Status and Productivity of RRIC 121 Genotype of Hevea brasiliensis (Rubber) under Different Harvesting Systems

Abstract

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Rubber (Hevea brasiliensis) one o f the main plantation crops in Sri Lanka is the only plant species cultivated com m ercially for natural rubber harvesting. N ovel system s for harvesting have been introduced but spatial distribution o f photosynthetic potential determining key factor for sustainable cultivation has not been properly explored. U se o f such techniques such as Satellite Remote Sensing (R S) and Geographic Information System (GIS) to analyse spatial and biological factors related to the productivity o f rubber plantation with different harvesting system s is the main objective o f the present study. Quikebird high resolution satellite im ages were used for RS analysis. Chlorophyll content o f rubber leaves was measured using a SPAD-502 chlorophyll meter. Chlorophyll content and satellite im ages were analysed using GIS and spatial statistical m ethods to determine the variation in different harvesting system s. Y ield data were collected from the study site and yield parameters were correlated w ith chlorophyll content and Norm alized D ifference V egetation Index (N D V I) values. R esults revealed all system s exhibited prom ising yield performance without significant deviation but slightly higher yield per hectare per year (YPH) and dry rubber content o f latex (DRC) were recorded in quarter spiral based once in three days (S/3 d4) and w eekly (S/2 d l 2d7) harvesting system s. Chlorophyll content and rubber yield showed direct correlation in all system s. NDVI vs chlorophyll showed positive correlation r2=0.65 and spatial distribution o f chlorophyll and N D V I values demonstrated sound physiological status o f plants across the plantation with different harvesting system s. Cost effective LIH system s showed better production trend demonstrating relatively higher yield w hile reducing tapping cost and labour. Satellite based remote sensing technique is an easy and efficient tool to estim ate productivity o f rubber plantation over a large area.