Distribution and accumulation of selected heavy metals in Tea plants
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Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
Uva Wellassa University of Sri Lanka
Abstract
Tea (Camellia sinensis (L.) O. Kuntze) is the mostly consumed beverage in the world after the water.
Currently, as a natural beverage, its demand is increasing drastically all over the world. But, with the
reporting of contamination of tea from different hazardous (Heavy metal, pesticides…etc.), which
cause adverse health consequences to human being, the attention for food safety regulations are being
promoted by the different counties to protect their people. As a result different quality assurance and
food safety regulations and certifications such as ISO, HACCP, GAP, MRL, Acceptable limits for
heavy metals …etc. have been introduced to the tea industry also.
At field level due to usage of agricultural fertilizers and pesticides, migration of contaminants into a
non-contaminated land as vapors and leach through soil, or as dust, or spreading of sewage
sludge…etc cause to contamination of tea from above mentioned hazardous. Among them,
contamination of tea from heavy metals has a critical issue. According to Sri Lanka Tea Board
Standard acceptable limits for Fe - 500, Cu – 100, Pb – 2, Zn – 100 and Cd – 0.2 mg/kg and each
country sets its own allowable limit for heavy metal in made tea.
Hence, this research was carried out as a primary study to find out the how those heavy metals are
being (zinc, copper and lead) distributed and accumulated in tea plants and the impact of Glyphosate
application for distribution and accumulation of those heavy metals. The ability of plants to tolerate
and accumulate heavy metals can be assessed using Translocation factor (TF) which is defined as the
ratio of metal concentration in the shoots to the roots ([Metal] Shoot/ [Metal] Root). Hence,
Translocation factor was calculated for each treatment and metal also.
Material and Methods
Experimental unit were 18 months old tea plants (TRI 4052) which were planted in pots and for 45
days experiment was carried out in a shade house of Uva Wellassa University, Badulla. Research
design was Complete Randomized Design. Control (Distilled water), Glyphosate (20 µl per pot) and
heavy metal mixture (Zinc 300, copper 300 and lead 200 mg/kg per pot) were applied to plants
diluting in 500 mL distilled water as treatments. Number of replications were five. Concentrations of
Zn, Cu and Pb were determined in shoots, mature leaves, stem, mature roots and feeder roots using
Atomic Absorption Spectroscopy after digested them. Plant tissues were digested using wet digestion
procedure, thoroughly washed (from the tap water and distilled water) tea plant parts were dried at
80 C overnight. They were ground and sieved through 1 mm mesh. 0.5 g of sample placed in a small
beaker and 5 ml of Con. HNO3 was added. Then, it was kept for overnight to digest the organic
compound in plant materials. Digested samples were heated on hot plate at 100 C for three hours
(until emission of NO2 fumes has ceased). Each sample was diluted with 25 ml of distilled water and
filtered through filter paper. Filtered transparent solution were analyzed using Atomic Absorption
Spectrometry.
Result and Discussion
There was a significant difference (p< 0.05) between the treatments on accumulation of each heavy
metal in different parts of tea plant. The treatment of Heavy metal mixture was significantly
Description
Keywords
Agriculture, Export Agriculture, Tea Industrials, Tea Technology