Phylogeny, Growth, Yield and Chemical Composition

4.1.1 Phylogeny

Miscanthus is a C4 perennial grass of tropical and subtropical origins with a wide area of distribution (Figure 4.1). It belongs to the Poaceae family, a subfamily of Panicoidae, the tribe of Andropogoneae and the subtribe of Saccharineae. Among others, the gen­era Miscanthus, Saccharum and Erianthus belong to this subtribe [8]. The phylogeny of Miscanthus was first described by Andersson in 1856 [9]. Miscanthus was introduced into Europe by Aksel Olsen, who brought it from Japan to Denmark in 1935 (reported by Atienza et al. [10]). Miscanthus sensu lato (s. l) comprises more than 20 species [11] while Miscanthus sensu stricto (s. s.) contains about 12 species [3]. There is no consensus yet on the definition of Miscanthus (s. l. or s. s.), the taxonomic system to be used or the number of species, subspecies, varieties and forms to be recognized. This can be attributed to the existence of natural interspecific hybrids, the famous one being M. x giganteus, issued

Table 4.1 Ranges of the main components of biomass for combustion. (Data collected from [39, 51-54] for M. x giganteus).

% of dry weight

mean

min

max

C

48.6

48.5

48.7

H

5.7

5.5

5.9

S

0.1

0.0

0.1

N

0.4

0.3

0.5

Cl

0.2

0.1

0.2

Ash

2.7

1.7

3.1

% of ash dry weight

mean

min

max

SiO2

53.3

47.0

63.7

K2O

18.8

14.8

23.7

CaO

6.3

4.6

7.7

P2O5

4.1

2.3

7.1

Fe2O3

0.5

0.2

1.0

Al2O3

0.7

0.2

1.7

MgO

3.2

1.9

4.6

Na2O

0.6

0.2

0.8

from a cross between M. sacchariflorus and M. sinensis. Furthermore, the distribution of each Miscanthus species has not been fully investigated [9].

Miscanthus is closely related to other genera of the “Saccharum complex” (the Sac — charum genera belonging to this complex) and Saccharum-Miscanthus hybrids, that is, miscanes, are used to create varieties of miscane [12]. Alix et al. [13] (Table 4.1) con­cluded that Miscanthus was more similar to Saccharum than Erianthus while Cai et al. [14] (Table 4.1) placed Miscanthus between Erianthus and Saccharum. However, a phy­logenetic analysis of more than 57 species belonging to the tribe Andropogoneae showed that Saccharum was in fact more closely related to Miscanthus than to other species in the Saccharum complex [11].

The original taxonomy of Miscanthus first described by Andersson (1856) has been subsequently modified many times using morphological measurements as reported by Sun et al. [9]. Recently, Sun et al. [9] revised the taxonomy of 500 Miscanthus accessions according to 41 morphological characters, of which 24 were qualitative traits and 17 quantitative traits (Figure 4.2).

Molecular methods have enabled the phylogeny of Miscanthus to be even more clearly defined such as in situations where morphological characters were not efficient. Molecular data, especially DNA data, provide a direct assessment of genetic diversity and unlike morphological characters are not influenced by environmental factors [15]. Using nuclear DNA, Greef et al. [16] assessed the genetic diversity of European Miscanthus species with Amplified Fragment Polymorphism (ALFP) and found it was a powerful tool in evaluating genetic diversity and hybrid success and in identifying incorrect classifications. Kim et al. [17] developed a sequence-characterized amplified region (SCAR) marker that clearly distinguishes M. sacchariflorus, M. sinensis and M. x giganteus. Using chloroplast DNA, De Cesare et al. [18] identified six chloroplast Single Sequence Repeat (cpSSRs) markers capable of differentiating most Miscanthus species.

image010

Figure 4.2 Taxonomy of Miscanthus Andersson from China. (Adapted from Sun et al. [9]. The corresponding key to taxa is reported by Sun et al. [9]).

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