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Abstract
Onokpise, O.U., D. Rockwood,
S.K. Bambo, and A. Jain. 2008. Performance
of cottonwood (Populus deltoides Bartr.) clones as a woody
biomass crop for phytoremediation. JEMREST 5:99-105.
Cottonwood (Populus), a fast growing hardwood was evaluated for use in phytoremediation of
polluted sites as well as a potential source of woody biomass for bioenergy.
Ramets of cottonwood clones were harvested from the North Florida Research
and Education Center,
Quincy, Florida
and planted in 3.8 litter greenhouse pots in 2003 and 2004 with 50 and 22
clones, for a replicated survival and
growth characteristic studies. An average of 4 ramets per clone was
planted in standard potting mix of
coconut fiber, perlite and peatmoss supplemented with granulated slow release
fertilizer applied four weeks after planting (WAP). Clonal survival rates were determined at 16
WAP, while number of bud break, number of leaves and height growth were determined from 8 to 16 WAP. In addition,
the plants were harvested at 32 WAP and evaluated for root biomass. Plant
tissues collected during the course of the experiment were analyzed for total
Kjeldahl nitrogen (TKN). In 2005-2006, stored leaves from each surviving
clones were analyzed for heavy metals (arsenic, copper, lead, and zinc).
Other observations made included leaf discoloration, vigor of growth, and
presence or absence of insect pests on leaves. There were significant
differences among clones for all characters studied except for heavy metals.
Survival rates ranged from 0 to 100% with an average of 35%. The mean number
of leaves ranged from 1 to 25, while mean number of bud break ranged from 1
to 5. Mean root biomass of clones at 32 WAP ranged from 5 g to 20 g. Clones
with greater than 25,000 mg/kg were significantly higher in TKN than those
having less than 15,000 mg/kg. Out of the twenty two P. deltoides
clones studied and considering all the growth characteristics, the best 5
clones included 115-1, 90-7, 133-3, 72C-2 and 105-1. Such P. deltoides
clones with superior growth characteristics will be needed to enhance
polluted sites and hence an alternate and cheaper method to clean up the
environment in a safe manner.
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