Assessment of oil yield and quality in cinnamon (Cinnamomum zeylanicum Blume) leaves under different severity levels of two types of leaf galls
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Date
2015
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Uva Wellassa University of Sri Lanka
Abstract
Leaf gall infestation in cinnamon, is one of the prominent pest damage found in cinnamon
cultivations. In cinnamon, two conspicuous leaf gall types are available. They are upper leaf
galls caused by jumping plant louse (Trioza cinnamomi), a homopteran and lower leaf galls
caused by Eriophyes boisi, a mite belongs to family Eriophyidae. Two pests are plant sappers
and form galls on leaf blade as their habitats. The feeding by Eriophyes boisi or Trioza
cinnamomi causes abnormal cell development and formation of galls. Each gall type is identical
and their dimensions are variable. The galls are solitary and widespread on the leaf blade but are
not on the veins. These Gall forming pests generally do little damage to plants and its bark yield
because the affected parts are able to carry out photosynthesis with near normal efficiency. But
cinnamon leaf oil yield and its quality may be changed significantly due to gall forming (Perera
et. al., 1985; Prematilaka and Dharmadasa, 1995). Therefore this study was conducted to
determine the effect of two different leaf galls in cinnamon leaves under different severity levels
on the leaf oil content and quality of oil.
Methodology
Cinnamon leaf samples infested with two types of galls, were collected from a field in
Palolpitiya, Matara. Leaves only suffered from upper and lower gall infestations were harvested
separately and categorized each of them into five pre-determined severity levels for oil
extraction. Four severity levels of upper leaf gall infestation 1-50, 51 – 100, 101 – 150 and more
than 151 galls per leaf and four severity levels of lower leaf gall infestation 1 -15, 16 – 30, 31 –
45 and more than 46 galls per leaf were compared with cinnamon leaves without galls
separately. Five treatments were assigned in randomized complete block design with five
replicates. 50 g of air dried cinnamon leaf sample taken from each severity level was weighed
and all the galls in the sample were isolated and weighed. Weight of galls in each severity level
was expressed as a percentage to the whole sample weight. Each sample was subjected to extract
leaf oil by hydro distillation. Amount of the major chemical components present in the extracted
oil samples were measured by performing Gas Liquid Chromatography (GLC). Oil content and
quality were subjected to analysis of variance and regression analysis by SAS programme.
Results and Discussion
Thus it revealed that leaf oil contents were significantly different with the intensity of upper gall
infestation (Table 1). It was observed that cinnamon leaf oil content had been lost from 10.48%
at 25.62% severity to 74.26% at 97.26% severity. Same trend was observed in the case of lower
gall infestation (Table 2), but oil reduction due to this infestation had been occurred from
25.87% at 22.7% severity to 96.45% at 99.63% severity. Experimental results showed that mite
galls (lower leaf galls) had reduced the oil yield in greater than the insect galls (upper leaf galls).
Both upper and lower leaf gall infestations were caused to reduce the oil yield in cinnamon
leaves and those infestations showed a strong negative significant relationship with the oil
content in cinnamon leaves (Fig. 1 and 2). Prematilaka and Dharmadasa (1996) reported about
35% of oil reduction could be made due to upper leaf gall infestation, but the current study
revealed that loss of oil content has been varied on severity of infestation.
Description
Keywords
Agriculture, Export Agriculture, Cinnamomum, Export Agriculture, Spices