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Laboratory and
green house experiments were conducted at
the Teaching and Research Farms, Ladoke
Akintola University of Technology, Ogbomoso,
Nigeria, in the year 2012, to evaluate the
effect of varying concentrations of copper
and zinc on germination, early growth and
biomass production of two selected arable
crops. The two sets of experiment were
factorial with two (2) levels of heavy metal
(copper and zinc) and six (6) levels of
their concentrations in ppm (0, 50, 100,
200, 400 and 500). The experiments were
arranged in completely randomized design
(CRD), replicated six (6) times. Data
collected were subjected to analysis of
variance (ANOVA), while the significant
means were separated using Duncan Multiple
Range Test (DMRT). Application of copper and
zinc at varying concentrations significantly
(p<0.05) influenced seed germination, growth
and biomass yield, under both laboratory
(filter paper) and green house (soil)
conditions. Seeds of both crops tested
failed to germinate at zinc concentrations
≥400ppm in the laboratory and green house.
However, total seed germination failure was
observed at copper and zinc concentrations
≥400ppm in the laboratory for grain
amaranth. However, zero germination was only
recorded at 500ppm concentrations of copper
and at ≥400ppm concentration of zinc, for
sesame in the laboratory. In the greenhouse,
there were no records on germination for
both tested crops at 500ppm concentrations
of copper and zinc. Also, under green house
conditions, sesame was observed to be more
tolerant to the heavy metals’ effects as
significantly higher cumulative germination
percentages were recorded at 400ppm,
compared to those of grain amaranth which
were not significantly different from 0.0%
recorded for 500ppm concentrations for the
assayed heavy metals. In addition, higher
the dosages of heavy metals significantly
affected growth and yield of the tested
crops, particularly at above 200ppm
concentrations. Both copper and zinc are
therefore adjudged as being highly
phytotoxic at relatively high dosages. Thus,
accumulation of heavy metals (particularly
copper and zinc) in soils, is undesirable
for sustainable arable crop production and
should therefore be totally discouraged in
the study.
Keywords: Copper, Zinc, Germination, Biomass
yield, Pollution, Sesame, Grain |
