Environmental Engineering Reference
In-Depth Information
taBle 19.2 (continued)
Brix (sugar content) and other Biomass-related trait values of sweet sorghum
cultivars/lines
days to
anthesis
Plant
height (cm)
Brix
reading
Wet stalk
(g/stalk)
dry stalk
(g/stalk)
stalk
moisture (%)
cultivar/line
Rancher
57
166
13.40
138.67
49.33
64.59
Leoti
63
170
13.67
353.33
119.33
66.19
Red Amber
62
190
11.87
305.00
100.00
67.06
Chinese Amber
68
220
16.93
406.67
133.00
67.09
Dakota Amber
67
192
14.27
255.00
87.33
65.64
Minnesota Amber
68.
174
14.00
305.00
108.66
63.70
Black Ambercane
59
190
13.20
268.33
93.00
64.97
Black-Amber
62
200
12.13
275.00
95.00
65.42
Early Folger
70
216
16.47
363.33
125.33
65.50
Cowley
75
202
16.67
508.33
162.33
68.05
Williams
78
224
15.93
670.00
202.00
69.85
Umbrella
71
226
15.47
596.67
172.66
70.92
Blacktop
57
168
7.13
258.33
75.66
70.62
Snowflake
85
216
17.06
583.33
187.66
67.61
Hastings
77
252
14.40
503.33
155.33
69.14
Iceberg Amber
81
204
15.73
606.67
179.667
70.24
White Orn
85
230
10.60
673.00
190.00
70.89
19.8.2 p
lant
h
Eight
Sweet sorghum may grow to 3-5 m tall. Height is desirable because it influence total biomass. There
is a strong correlation between photoperiodism and plant height. The longer the plant remains in
the vegetative stage, the greater the number of nodes and leaves. There are four unlinked genes that
affect the total number of internodes. These genes exhibit partial dominance and were designated
dw1
,
dw2
,
dw3
, and
dw4
. Several studies have identified and mapped quantitative trait loci (QTL)
that affect plant height using recombinant inbred populations (Lin et al. 1995; Pereira and Lee
1995). The map locations of these QTL seem to be similar in maize and sorghum and indicated that
possible homologies exist with maize QTL and mutations known to affect plant height.
19.8.3 l
lignin
c
oncEntrationS
Lignin concentration is important component in any bioenergy crop. In sweet sorghum, both high
and low lignin level lines could be utilized. Low lignin lines are suitable feedstock for cellulosic-
based ethanol, whereas high lignin lines are desirable for co-firing to produce electricity. Brown
midrib mutation in cereals affects lignin level. The brown midrib (
bmr
) mutations were first
discovered in corn 1926. Early studies revealed the trait resulted in lower fiber and lignin within
the plant and could increase the conversion efficiency of sorghum biomass for lignocellulosic
bioenergy. In sorghum, more than 19
bmr
mutants were discovered by Porter et al. (1978). The
bmr
mutants are characterized by the reddish-brown coloration of the vascular tissue of the leaf
blade, leaf sheath, and stem that is associated with alteration of secondary cell wall composition,
especially lignin. Because of the development of biocatalysts (e.g., genetically engineered enzymes,
yeasts, and bacteria), it is possible to produce ethanol from any plant or plant part containing
lignocellulose biomass, including cereal crop residues (stovers). Sorghum stover also serves as an
excellent feedstock for ethanol production. Stover contains lignin, hemicellulose, and cellulose.
The hemicellulose and cellulose are enclosed by lignin (which contains no sugars), making them
