Biomedical Engineering Reference
In-Depth Information
biomass feedstock production (substituting fossil fuels) and through C sequestra-
tion in the soil. The mean total C stock of six sites of seminatural grasslands in
Mt. Aso, Japan, which have been managed for more than 7,000 years, was 232 Mg
Cha
1
(28-417 Mg C ha
1
). This equates to a soil C sequestration rate of 32 kg C
ha
1
year
1
over 7,300 years.
Miscanthus
being the predominant C
4
plant species
in the grassland exhibits tremendous potential as a stable C sink [
52
]. The semi-
natural grasslands in Aso potentially acts as an important C sink in Japan because of
their ability to sequester large amounts of atmospheric C. The coupled natural and
human systems of the seminatural grassland in Aso act as a model in terms of
demonstrating the sustainable use of grassland for animal and renewable bioenergy
production as they relate to C accumulation in soil [
52
,
53
].
Miscanthus
is still a new bioenergy crop. Scientists, primarily those in Europe
[
20
,
54
-
56
] and the USA [
13
,
57
,
58
] have evaluated the potential of several
members of the
Miscanthus
genus as bioenergy crops, particularly high-yielding
taxa such as
M. sinensis
,
M. sacchariflorus
, and their hybrids [
21
,
55
]. Owing to its
C
4
photosynthesis [
59
], low-nutrient requirement [
60
], high water-use efficiency
[
61
], capability of C mitigation [
21
], and high yields in various climates and
environments [
25
],
M.
giganteus
has been determined as a very promising
bioenergy crop [
13
,
17
,
62
,
63
].
It has been reported that in the USA 11.8 million hectares (ha) of
M.
giganteus
would be required to produce 35 billion gallons of ethanol per year. In comparison,
it would require 18.7 million ha of corn (grain plus stover) or 33.7 million ha of
switchgrass to produce the same volume of ethanol [
13
].
Recent cultivation of
Miscanthus
as energy crop has gained momentum, and
hectarage has increased mostly in Europe and somewhat in the USA. But much
remains of further expansion to other geographical areas of suitable climate. The
adoption of
Miscanthus
as biofuel feedstock on industrial scale is still being
awaited.
M.
giganteus
clones that are now available in the market all seem to have been
derived from a single plant introduced by a Danish plant collector, Aksel Olsen,
into Europe from Yokohama, Japan, in 1935 [
64
].
M.
giganteus
(2
n
¼
3
x
¼
57) is
a natural triploid hybrid between diploid
M. sinensis
(2
n
¼
2
x
¼
38) and tetraploid
M. sacchariflorus
(2
n
giganteus
has been also known
as
M. sinensis
“Giganteus,”
M. ogiformis
, and
M. sacchariflorus
var.
brevibarbis
.
Recent classification work at the Royal Botanic Gardens at Kew, England, has
designated it as
M.
¼
4
x
¼
76) [
30
,
65
,
66
].
M.
giganteus
Greef & Deuter ex Hodkinson & Renvoize [
67
], a
hybrid of
M. sinensis
Anderss. and
M. sacchariflorus
(Maxim.) Bentham. [
65
,
68
].
M.
giganteus
is a sterile triploid, so it can be propagated only asexually by its
rhizomes [
30
,
65
]. Molecular marker analysis on several
M.
giganteus
clones
showed that there is very little genetic variation between clones [
30
,
65
]. This
apparent genetic uniformity increases
M.
giganteus
vulnerability to diseases,
pests, and environmental stresses [
25
]. Furthermore,
M.
giganteus
sterility
prevents development of new varieties of
M.
giganteus
[
25
].
giganteus
was about 12,700 ha in the UK and 4,000 ha
in Poland in 2009 [
16
]. In the USA (Arkansas, Missouri, Ohio, and Pennsylvania),
M.
The area planted to
M.
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