Agriculture Reference
In-Depth Information
by the spectral data are expected to result in greater efficiency in the crop yield
estimation.
2.2 Application of GIS and Remote Sensing in Tea Plantations
Even though remote sensing has been widely used for forecasting the yield of dif-
ferent types of crops, understanding of the spectral characteristics of tea plantations
is very important for monitoring the growth of plants and estimating harvested leaf
yield. Spectral characteristic of tea estates varies depending on age of tea canopy,
type of tea 'jat', and health of tea plantation.
To facilitate convenient height for harvesting, stimulate vegetative growth, main-
tain healthy frames andoptimize resource utilization. Tea bushes are required to be
pruned at regular intervals. The time period between two consecutive prunings is
known as pruning cycle. However, the length of the pruning cycle varies according
to the location of the estate and type of tea. The pruning cycle of seedling tea can be
two, three or four years corresponding to low-country, mid-country and upcountry.
Pruning cycle of vegetatively propagated tea is three, four and five years for low-
country, mid-country and upcountry, respectively. Generally, most tea plantations
show relatively similar spectral characteristics such as higher absorption in red and
large reflectance in NIR bands. However, spectral characteristic of tea also depends
on its canopy structure, size of the leaves, greenness and maturity of leaves, hence
tea plants with different pruning cycles give different spectral signatures (Rajapakse
et al.
2002
).
According to Rajapakse et al. (
2002
), the reflectance of clonal and seedling
tea depends on tea canopy structure, size of the leaves, greenness and maturity of
leaves. However, in general most of clonal and seedling tea types display relatively
similar spectral trend. One important factor is canopy age which is calculated from
its last pruning and according to Rajapakse (
2002
) younger plants absorb light be-
tween 600 and 625 nm whereas older plants with matured leaves absorb more light
at 650 nm. However, the variation depends on tea clones but both younger clonal
and seedling tea have low reflectance in NIR (800-1,050 nm) than mature canopy.
Therefore, tea plants show different reflectance spectra according to their canopy
age and tea clone.
Computer technology has advanced over the last few decades and one of the
most important applications of it is the database management, where computers
are used to store information for quick access and analysis. GIS data have specific
location in space; In other words, those spatial data have been referenced to a co-
ordinate system. It is called geographically referenced. It is also possible to store
non-spatial or attribute data in such databases. Therefore, GIS is able to store large
amounts of different types of data for easy access. Furthermore, the spatial data
can be combined with attribute data to generate new information in the decision-
making process. Hence, tea plantations where the spatial distribution is massive, use
