Abstract:
Measuring the chlorophyll content of a plant is generally done by using laboratory techniques and
field testing equipment. Modern remote sensing approaches have a potential to identify the
correct quantity of chlorophyll in the fields. There are many plant indicess that have been
developed for measuring leaf chlorophyll content. Traditional approaches of measuring leaf
chlorophyll may incur high costs and can be time consuming in large fields. Hambantota district
is considered as a large-scale paddy cultivating area. Paddy lands from Ranna, Hungama and
Angunukolapelessa cities were selected for this analysis. Drone images, Landsat 8 satellite
images were collected from each field corresponding to field sampling dates. Paddy leaf samples
were collected to measure the actual chlorophyll content. Laboratory acetone extraction method
was used to estimate the actual chlorophyll and ArcGIS software was used to develop the
normalized difference vegetation index (NDVI) maps, Visible atmospherically resistant index
(VARI) maps and land surface temperature (LST) maps of the three selected paddy fields.
Chlorophyll content calculated from the satellite images and drone images was compared with
actual laboratory leaf chlorophyll content to build an index and to find the correlation between
them. It was possible to identify a positive correlation (R2= 0.7268) between NDVI and the plant
chlorophyll content. It was observed that the LST maps and NDVI maps developed graphycally
show inverse relationships. In addition, VARI maps can be used similarly as NDVI maps to
estimate the chlorophyll content of the paddy leaves. Instead of satellite images, low cost drones
which have no near infrared spectroscopy (NIR) sensors are suitable for measuring the plant
chlorophyll content using the VARI.Therefore, more investigations should be done on the
applications of drone and satellite images as a non - destructive method to estimate the
chlorophyll content of paddy leaves.
