Journal of Tea Science Research. 2015, Vol. 5, No. 6, 1-13
3
Table 2 Effect of repeated applications of copper oxychloride (COC) on Pb content in black tea
Treatment
(Dosage/ha)
Pre-tre
atment
Pb content in black tea (mg kg
-1
)
I
st
week after
I spray
II spray
III spray IV spray V spray
VI spray
VII
spray
Mean
Untreated control
0.89
0.97
0.86
0.79
0.82
0.81
0.82
0.83
0.84
COC+Hexaconazole(210
g + 200ml)
0.85
1.11
1.73
1.37
1.67
1.46
1.99
1.64
1.57
COC alone
210 g
0.91
1.02
1.50
1.25
1.89
1.64
1.84
1.62
1.54
S.E. m ±
0.12
C.D. at P = 0.01:
0.36
C.V. (%):
5.23
Data presented in the parenthesis denote green leaves sampling of foliar application of fungicides
Baby, 2005). COC is a source of Pb contamination.
To generate information on the accumulation of Pb
due to foliar application of COC, a field experiment
was conducted at the Tea Experimental Farm,
between July and September. Experimental plots
were laid in randomized block design in a clonal tea
field. Each plot measured 10 m x 10 m and plots
were separated by three guard rows to prevent drift
while spraying. There were three treatments,
viz.,
COC 210 g ha
-1
, COC in combination with
hexaconazole (210 g + 200 ml ha
-1
) and untreated
control. All the treatments were replicated in seven
plots. Foliar application was done using hand
operated knapsack sprayer with a spray volume of
175 l ha
-1
. Two kg of the harvested crop was
sampled from each plot on the seventh day after
application and also before the next round of
fungicide application. Sampled green leaf was
processed into black tea in the mini manufacturing
unit, as described earlier. The processed black tea
samples were subjected to elemental analysis.
3.3 Sample preparation
The lead traces in the copper oxychloride fungicides
were determined as reported by Franklin et al.
(2005). About 1 g of solid or 1 ml of liquid sample
was digested with 20 ml of aqua regia (HCl: HNO 3 ,
v/v 3:1) on a hot plate until a clear solution was
obtained. The digested mixture was diluted with
deionised water and made up to the mark in 100 ml
pre-calibrated volumetric flasks. Samples were
further diluted to 10 times with deionised water and
analysed in GF-AAS. (Perkin Elmer AAnalyst 800,
TheNetherlands).
The tea samples were processed following the
methodology as described in AOAC,
2000. In a
washed clean dry crucible, 0.5g of sample (black tea)
was weighed and kept in a muffle furnace at 450°C
for 3 hours. After ashing 5 ml of 0.6 M HCl was
added and the acid solution was allowed to
evaporate in a hot plate. The residues filtered (using
Whatmann filter paper No. 545) in 50 ml volumetric
flask using 0.1 M HNO
3
. Simultaneously blank was
also prepared without sample. All glassware and
polyethylene sample containers were washed with
tap water after each use, soaked (over night) in 6N
HNO
3
solution and rinsed several times with
distilled water (Cabrera et al., 1994), in order to
minimize the absorbance due to impurities.
Authors Contributions
SS conducted the field trials, sample preparation,
metal analysis and interpreted the results. NM
approved the protocol and drafted the manuscript.
