ARTICLE pubs.acs.org/EF
Elemental Concentrations in Triticale Straw, a Potential Bioenergy Feedstock H. M. El-Nashaar,† G. M. Banowetz,*,† C. J. Peterson,‡ and S. M. Griffith† †
United States Department of Agriculture/Agricultural Research Service, 3450 Southwest Campus Way, Corvallis, Oregon 97331, United States ‡ Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon 97331, United States ABSTRACT: Triticale (Triticosecale Wittmack) is a small cereal grain crop produced for livestock feed and forage on more than three million hectares (ha) worldwide including 344 000 ha in the U.S.A. After the grain is harvested, triticale straw residue could provide feedstock for bioenergy production in many regions of the world, but high concentrations of certain elements, including silicon (Si), potassium (K), and chlorine (Cl) that are characteristic of other cereal straws, impact their suitability for use in thermochemical conversion technologies. Also, straw harvest is associated with the removal of macro- and micronutrients from crop production systems and may impact the long-term sustainability of residue removal. We quantified the concentrations of seven elements in chaff, grain, leaves, and stems harvested from eight triticale cultivars grown in western Oregon to determine whether there was genotypic variability that may impact the concentrations of these elements. On average, harvest of the chaff, leaves, and stems combined removed 9.6 g of nitrogen (N), 5.3 g of phosphorus (P), and 80 g of K kg-1 of biomass. Harvest of the grain alone removed 21.7, 3.1, and 4.8 g kg-1 of N, P, and K, respectively. The Si content of chaff and leaves ranged from 17 583 to 37 163 mg kg-1 of biomass. Straw from the genotype Taza contained the least amount of Si. The variability and range of concentrations of elements among these cultivars suggests that genetic approaches would not only modify the composition of macro- and micronutrients but also would improve the utility of triticale straw as bioenergy feedstock. Chaff, leaves, and stem components of triticale are relatively uniform in their energy contents that range between 17.51 and 17.96 MJ kg-1. Selective harvest of triticale straw components could reduce the content of Si and other minerals that impact the use of this biomass in thermochemical conversion processes.
’ INTRODUCTION Triticale (Triticosecale Wittmack), a small grain cereal crop, is known to produce large amounts of biomass1 and is commonly used in crop production on marginal land.2 This crop is typically grown as a forage for livestock feed.3 Triticale may also have utility in double-cropping systems to provide animal feed as well as biomass for bioenergy.4 Triticale has favorable agronomic characteristics including broad spectrum disease resistance5 and requires minimal capital investment for small grain crop production systems, a factor that contributes to its utility in providing an inexpensive bioenergy feedstock. Escalating oil prices, reservations regarding the stability of future fuel supplies, and the need for renewable energy have led to the evaluation of the potential of crop residue biomass or dedicated bioenergy crops as raw material for energy production.6 Straw residues resulting from the production of grass seed, wheat, and other cereals are abundant and have potential as biomass feedstock for bioenergy production.7-11 Triticale crop residues may have similar potential. Although these straws may have utility as bioenergy feedstock,6 there is a need to return a portion of crop residues to the production field to sustain soil productivity, reduce wind and water erosion, and maintain soil fertility.12 Recommendations for the amount of residue that should be left in the field are based on environmental conditions, soil type, location, and cropping systems.13 In many cases, the amount of residue that exceeds the amount needed for conservation purposes may serve as feedstock.14 A major concern regarding the removal of crop residues from r 2011 American Chemical Society
agroecosystems for utilization as bioenergy feedstock is the sustainability of soil productivity and ecosystem services.15-17 Replacement of nutrients represents an input cost that must be factored into any economic and ecological analysis of straw utilization. The presence of certain elements in crop residues like small grain straw also influence the suitability of this biomass for thermochemical conversion. Thermochemical conversion technologies like gasification and pyrolysis that are scaled and designed to process crop residue biomass are still in development. Consequently, well-defined feedstock quality and mineral composition requirements are still being determined. Nevertheless, previous research with other straws and field residues suggests that technology constraints impact the suitability of cereal straw as bioenergy feedstock.18 Thermochemical approaches like gasification rely on relatively high-temperature treatment of the biomass to produce syngas that is suitable for power generation or gas/liquid fuel production. Such processes are accomplished at operational temperatures where carbon (C) conversion efficiency is high,19 but silicon (Si), which is abundant in most cereal and grass straws, and sulfur (S) react with potassium (K), chlorine (Cl), and other alkalis to form a sticky glasslike agglomeration of alkali silicates (slag) at these temperatures.18,20 Chlorine content is frequently Received: September 14, 2010 Revised: January 5, 2011 Published: January 25, 2011 1200
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Table 1. Proximate and Ultimate Analyses of Moisture Free Samples of Triticale (Triticosecale Wittmack) Plant Components plant component
heating value (MJ kg-1)
moisture (%)
ash (%)
volatile matter (%)
fixed C (%)
C (%)
H (%)
N (%)
S (%)
O (%)
stem
17.96
6.18
5.79
76.7
17.6
49.0
5.55
0.45
0.18
41.4
leaf
17.54
6.38
9.71
74.4
15.9
47.2
5.49
0.83
0.18
40.5
chaff
17.51
6.97
9.19
73.9
16.9
47.4
5.48
1.00
0.13
40.5
Table 2. Proximate and Ultimate Analyses of Moisture-Ash Free (MAF) Samples of Triticale (Triticosecale Wittmack) Plant Components plant component
heating value (MJ kg-1)
volatile matter (%)
fixed C (%)
C (%)
H (%)
N (%)
S (%)
O (%)
stem
19.06
81.4
18.6
52.0
5.89
0.480
0.190
41.4
leaf
19.43
82.4
17.6
52.3
6.00
0.920
0.200
40.5
chaff
19.28
81.4
18.6
52.2
6.03
1.100
0.140
40.5
Table 3. Mean (n = 3) Chlorine Concentration of Different Plant Components (Chaff, Grain, Leaves, and Stem) and Leaf-Stem-Chaff Combined (Lsc) of Eight Triticale (Triticosecale) Cultivars Grown at Hyslop Farm, Benton County, Oregon, U.S.A.a cultivar (g kg-1)
a
plant component
OR7040179S1
OR7040055
OR7040179S2
Fidelio
Taza
Parma
Celia
Bobcat
chaff grain
0.348 d 0.856 b
0.342 de 0.414 e
0.408 bc 0.576 d
0.589 a 0.638 cd
0.372 cd 0.911 b
0.51 b 0.713 c
0.304 ef 0.686 cd
0.291 f 1.17 a
leaf
1.34 b
1.71 a
1.82 a
1.65 a
1.15 bc
1.06 c
1.09 bc
0.439 d
stem
1.73 a
1.75 a
1.35 b
1.25 bc
1.22 c
1.14 c
0.917 d
0.268 e
Lsc
1.14 ab
1.27 a
1.19 ab
1.16 ab
0.914 ab
0.886 ab
0.770 bc
0.333 c
Values within rows followed by the same letter were not significantly different (p = 0.05).
associated with corrosion and deposition of alkali chlorides.21 Slagging and fouling corrodes metal surfaces of boilers and severely affects their maintenance, performance, operational cost, and lifespan.22-24 Compared to coal and wood, straw contains greater amounts of the alkali elements that contribute to slag formation and fouling.18 Cereal genotypes that contain lower concentrations of these alkali elements would likely be more suitable as feedstock for thermochemical conversion.25 The objective of this research was to quantify constituent elements of contrasting triticale genotypes to estimate the relative suitability of different selections and plant tissues as bioenergy feedstock and to quantify the amount of macro- and micronutrients removal associated with crop harvest. In conjunction with similar data from other cereal and grass straws, this information will prove useful in developing sustainable and economic thermochemical approaches to convert grass and cereal straws to bioenergy in a manner that preserves long-term sustainability of crop production within agroecosystems.
’ MATERIALS AND METHODS Plots were established in October 2006 at the Oregon State University (OSU) Hyslop Research Farm (Corvallis, OR) (44° 380 0100 N, 123° 120 0100 W; 70 m elevation) on a moderately well-drained Woodburn silt loam (fine-silty, mixed, mesic Aquultic Argixerolls). Eight triticale cultivars, representing broad genetic diversity, were selected for these trials. Genotypes were planted in 6-row plots (1.25 4.57 m) with cultivars arranged in a randomized complete block design (RCBD). Blocks represented the replications and plots represented the cultivars. Four blocks represented the replications, but only three of the four replications were sampled for this study and analyzed for elemental content. Triticale plots were harvested after plants matured by cutting the plants 6 cm above the
soil surface, placing the harvested tissue in paper bags, and allowing the plants to dry naturally in a greenhouse until processing. Ten to fifteen plants from each cultivar were separated into head, leaf, and stem components. Heads were hand-threshed and the grains were separated from the chaff. A total of 96 samples (eight cultivars, three replicates, and four discrete tissue samples) were prepared for elemental analysis as previously described.9 Briefly, plant samples were processed for K, P, and Si analysis with the microwave-assisted acid digestion (EPA method 3052) using an Ethos D microwave station (Milestone, Monroe, CT). The digested samples were subsequently analyzed on an inductively coupled plasma optical emission spectrometer (ICP-OES) (Perkin-Elmer Life and Analytical Sciences, Shelton, CT). For Cl analysis, 25 g samples were extracted with 100 ml of deionized water and shaken for 30 min at 350 rpm. After shaking, samples were filtered through Whatman Qualitative No. 42 filters (Florham Park, NJ) that had been washed three times with 1% H2SO4 (v/v) and deionized water. The filtrate was analyzed colorimetrically for Cl (QuickChem method 10-117-07-1-C) on a Lachat flow injection autoanalyzer (Hach Co., Loveland, CO). For total C, N, and S analyses, plant material was ground using a Tecator Cyclotec 1093 sample mill and then analyzed using a LECO TruSpec combustion analyzer (LECO Corp., St. Joseph, MI). Ultimate and proximate analyses of pooled samples representing equal amounts of each genotype were performed by Wyoming Analytical Laboratories (Laramie, WY) using American Standardized Test Method (ASTM) D5142/5373 for the ultimate analysis and ASTM D-5142 for the proximate analysis. The heating values of the pooled samples were obtained using ASTM D-5865. Statistical analyses of mean differences among triticale populations were calculated by applying PROC MIXED analysis procedures of SAS (Statistical Analysis System Institute, Cary, NC) in an RCBD. In the analysis of variance models, samples were considered random and cultivars were considered fixed. Mean concentrations of each element were 1201
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Table 4. Mean (n = 3) Sulfur Concentration of Different Plant Components (Chaff, Grain, Leaves, and Stem) and Leaf-Stem-Chaff Combined (Lsc) of Eight Triticale (Triticosecale) Cultivars Grown at Hyslop Farm, Benton County, Oregon, U.S.A.a cultivar (g kg-1) plant component ns
a
OR7040179S1
OR7040055
OR7040179S2
Fidelio
Taza
Parma
Celia
Bobcat
chaff
0.46
0.41
0.50
0.41
0.49
0.42
0.49
0.39
grain
1.00 bc
0.82 c
1.03 bc
0.81 c
1.24 ab
1.06 abc
0.99 bc
1.32 a
leaf
0.60 cd
0.61 cd
0.77 ab
0.82 a
0.68 bc
0.56 cd
0.55 d
0.53 d
stem
0.52 a
0.44 b
0.43 b
0.55 a
0.31 c
0.31 c
0.31 c
0.26 c
Lsc
0.53 abc
0.49 abcd
0.49 abcd
0.59 a
0.49 abcd
0.43 cd
0.45 bcd
0.39 d
Values within rows followed by the same letter were not significantly different (p = 0.05). ns = not significant (p = 0.05).
Table 5. Mean (n =3) Silicon Concentration of Different Plant Components (Chaff, Grain, Leaves, and Stem) and LeafStem-Chaff Combined (Lsc) of Eight Triticale (Triticosecale) Cultivars Grown at Hyslop Farm, Benton County, Oregon, U.S.A.a cultivar (g kg-1) plant component
a
OR7040179S1
OR7040055
OR7040179S2
Fidelio
Taza
Parma
Celia
Bobcat
chaff
26.31 b
28.55 b
37.16 a
29.13 b
17.58 c
26.68 b
23.24 bc
25.96 b
grain
0.170 cd
0.197 bcd
0.158 d
0.200 bc
0.183 cd
0.091 e
1.34 a
0.236 b
leaf
21.16 cde
35.46 a
24.57 b
24.17 bc
17.91 e
19.24 de
22.43 bcd
21.07 cde
stem
7.43 b
11.26 a
7.96 b
12.15 a
4.40 d
6.12 c
7.19 bc
6.13 c
Lsc
18.30 ab
25.09 a
23.23 a
21.82 ab
13.30 b
17.35 ab
17.62 ab
17.72 ab
Values within rows followed by the same letter were not significantly different (p = 0.05).
Table 6. Mean (n = 3) Potassium Concentration of Different Plant Components (Chaff, Grain, Leaves, and Stem) and Leaf-Stem-Chaff Combined (Lsc) of Eight Triticale (Triticosecale) Cultivars Grown at Hyslop Farm, Benton County, Oregon, U.S.A.a cultivar (g kg-1) plant component
a
OR7040179S1
OR7040055
OR7040179S2
Fidelio
Taza
Parma
Celia
Bobcat
chaff
4.86 d
4.54 de
4.22 e
5.77 b
5.28 c
6.70 a
4.75 d
5.39 c
grain
5.55 a
4.95 bc
4.30 de
5.10 b
4.02 e
4.76 bc
4.93 bc
4.62 cd
leaf
18.93 b
16.76 bc
21.69 a
18.90 b
15.49 cd
13.90 d
14.53 cd
9.93 e
stem
15.32 ab
19.14 cd
28.58 a
19.44 cd
22.96 bc
21.06 bcd
17.04 d
10.97 e
Lsc
16.37 a
13.48 ab
18.16 a
14.71 ab
14.58 ab
13.89 ab
12.11 ab
8.76 b
Values within rows followed by the same letter were not significantly different (p = 0.05).
evaluated for each of the four fractions (chaff, grain, leaves, and stems) and sources of variation in each of the triticale fraction were compared by applying Tukey’s Studentized Range (HSD) test using SAS.
’ RESULTS Proximate and ultimate analyses showed that the combustible properties of leaves, stems, and chaff were similar, although stem tissue appeared to have a lower ash content (Tables 1 and 2). The heating values of the three tissue samples were relatively uniform. There were 4-fold or greater differences in the concentrations of Cl in the leaves and stems harvested from these genotypes (Table 3). In general, Bobcat contained the least amount of this element while the greatest concentrations of Cl in leaf and stem tissue occurred in OR7040055 and OR7040179S2. In contrast, the concentration of Cl in grains was greatest in Bobcat and lowest in OR7040055 and OR7040179S2. Chaff, tissue remaining from the threshed heads after the grain was separated, generally contained
lower quantities of Cl. The relative Cl concentrations in composite samples consisting of leaf, stem, and chaff largely reflected the concentrations measured in leaf and stem tissue. The concentrations of S were generally greater in triticale grains relative to those measured in the components of straw residue (Table 4). The S concentrations were markedly lower than those of Cl. Bobcat contained the least S in stem and leaf tissues. Grains contained relatively small quantities of Si except for those measured in Celia, which were 5- to 10-fold that measured in the other seven genotypes (Table 5). The concentrations of Si were approximately 3-fold greater in leaves and chaff than in stem tissue. Taza tissues were relatively low in Si while OR7040055 and OR7040179S2 contained greater concentrations of this element. With the exception of Si (Table 5), the concentrations of K (Table 6) were consistently greater than those of the other elements (Tables 3, 4, and 7-9). Stem and leaf tissues generally contained similar concentrations of K; Bobcat contained the 1202
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Table 7. Mean (n = 3) Carbon Concentration of Different Plant Components (Chaff, Grain, Leaves, and Stem) and Leaf-Stem-Chaff Combined (Lsc) of Eight Triticale (Triticosecale) Cultivars Grown at Hyslop Farm, Benton County, Oregon, U.S.A.a cultivar (g kg-1)
a
plant component
OR7040179S1
OR7040055
chaff
416 b
405 c
grain
407 c
406 c
leaf
410 dc
stem Lsc
OR7040179S2
Fidelio
Taza
Parma
Celia
Bobcat
403 c
398 c
427 a
417 ab
416 b
422 ab
414 ab
405 c
416 a
410 abc
408 bc
410 abc
390 e
420 abc
414 bc
431 a
427 ab
397 de
423 abc
431 ab
415 c
433 ab
411 c
439 ab
430 ab
426 bc
444 a
419 bc
403 d
419 bc
408 cd
432 a
425 ab
413 cd
430 ab
Values within rows followed by the same letter were not significantly different (p = 0.05).
Table 8. Mean (n = 3) Nitrogen Concentration of Different Plant Components (Chaff, Grain, Leaves, and Stem) and Leaf-Stem-Chaff Combined (Lsc) of Eight Triticale (Triticosecale) Cultivars Grown at Hyslop Farm, Benton County, Oregon, U.S.A.a cultivar (g kg-1) plant component
a
OR7040179S1
OR7040055
OR7040179S2
Fidelio
Taza
Parma
Celia
Bobcat
chaff
11.82 abc
9.66 e
10.00 de
11.20 bcd
12.22 ab
11.36 bcd
10.71 cde
13.16 a
grainns
23.01 b
20.92 cd
19.72 e
19.10 f
23.42 b
20.72 d
21.37 c
25.32 a
leaf
10.86 abc
9.38 cd
11.47
9.02 d
10.92 ab
9.61 bcd
10.45 abcd
11.14 ab
stem Lscns
7.03 bc 9.90
6.88 bc 8.64
9.68 a 10.38
6.62 bcd 8.95
7.60 b 10.25
6.94 bc 9.30
6.25 cd 9.14
5.63 d 9.98
Values within rows followed by the same letter were not significantly different (p = 0.05). ns = not significant (p = 0.05).
Table 9. Mean (n = 3) Phosphorus Concentration of Different Plant Components (Chaff, Grain, Leaves, and Stem) and Leaf-Stem-Chaff Combined (Lsc) of Eight Triticale (Triticosecale) Cultivars Grown at Hyslop Farm, Benton County, Oregon, U.S.A.a cultivar (g kg-1) plant component
a
OR7040179S1
OR7040055
OR7040179S2
Fidelio
Taza
Parma
Celia
Bobcat
chaff
1.44 a
1.04 c
1.11 c
1.25 b
1.04 c
1.02 c
1.08 c
0.881 d
grain
3.54 a
3.45 ab
3.11 bc
3.02 cd
2.65 de
3.35 abc
3.37 abc
2.56 e
leaf
0.870 b
0.558 cd
1.15 a
0.781 bc
0.503 d
0.499 d
0.846 b
0.328 d
stem
0.551 b
0.484 b
0.752 a
0.569 b
0.308 c
0.168 d
0.314 c
0.158 d
Lsc
0.952 a
0.693 abc
1.00 a
0.868 ab
0.617 bc
0.563 bc
0.747 abc
0.456 c
Values within rows followed by the same letter were not significantly different (p = 0.05).
lowest concentrations of K in these tissues. The range of K among these genotypes was greater than 2-fold with OR7040179S2 frequently containing the greatest concentration. Chaff and grain contained less K. Differences in C concentration existed among these cultivars, but the range of concentrations tended to be small relative to that observed in the other elements that were quantified in this study (Table 7). In general, Taza tissues contained the greatest amounts of C among these cultivars. Nitrogen concentrations were highest in grains and lower in the order of chaff, leaves, and stems (Table 8). Grains contained up to 4-fold greater concentrations of N than stem tissue. The concentrations of P, a critical plant nutrient were greatest in grains and frequently lowest in stem tissues (Table 9). Bobcat tissues contained lower quantities of this element while OR7040179S2 contained the greatest amount measured in the composite (Lsc)
tissue samples. Like the case with Si, leaf tissue contained greater amounts of P than stems.
’ DISCUSSION Feedstocks vary in chemical and physical characteristics, which determine their utility as biomass for thermochemical conversion. The heating values of triticale chaff, leaves, and stems ranged from 17.51-17.96 MJ kg-1 and were similar to those reported for switchgrass (16.8-18.6) and hybrid poplar (17.7 MJ kg-1).26 Our results suggest that genotype and tissue selection will affect the success of thermochemical conversion of triticale biomass to energy. Previous research demonstrated differences in the concentrations of N, P, K, Ca, Mg, Mn, Fe, and Zn in the shoots and roots and grain of a selection of triticale genotypes grown to grain maturity under greenhouse conditions in Portugal.27 They 1203
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Energy & Fuels found cultivar differences in the accumulation of K and Ca when the concentration of Mn in the growth medium was altered. The Ca concentrations in shoots were more sensitive to Mn than those measured in roots and grain. Similar to the results reported here, their study also showed marked differences in the concentrations of most elements between roots, shoots, and grains. The concentrations of the eight elements they analyzed were similar to those found in the corresponding elements quantified in our study, but the magnitude of the differences between cultivars was less than we observed. In contrast, 14 experimental triticale lines produced in India had similar concentrations of P and K as those reported here, but the differences among cultivars were frequently 2-fold or greater.28 Another study reported differences in the grain concentrations of Ca, P, Fe, and Zn among 12 cultivars of triticale, but the concentrations of K, Mg, Si, Mn, and Cu were not different.29 With the exception of Mn and Zn, the grain concentrations of 9 elements were greater among 10 triticale lines than that associated with production under different environmental conditions.30 Previous studies also demonstrated that genotype had a large impact on the accumulation of Si and other elements in native and cultivated grasses and in wheat.7-11,31 Similarly, we showed that the utility of triticale biomass for thermochemical conversion, and the impact of straw harvest on soil micronutrient concentrations is genotype dependent. Although the range of N concentration in straw components of these genotypes was relatively narrow, the distribution of this nutrient among triticale straw components is similar to that reported in winter wheat (Triticum aestivum L.) where N distribution also varied with genotype.32 Our study showed that genotype influences the quantity of N in leaves, stems, grain, and chaff. Bobcat, Taza, and OR7040179S1 contained the highest concentration of N and Fidelio the lowest. Among other plant nutrients, the ranges of P and K concentrations we observed were greater than 2-fold. Bobcat and Taza frequently contained the lowest concentrations of the elements measured in this study while OR7040055 and OR7040179S2 often contained the greatest amounts. The need to replace macro- and micronutrients removed from the crop production system by straw harvest needs to be considered as an integral component of estimating the economical and ecological cost of straw removal. In addition to the need for nutrient replacement associated with straw harvest, long-term sustainability of the practice must also consider erosion control, maintenance of soil carbon and organic matter content, and providing habitat for soil micro- and macrofaunal components such as earthworms, which contribute to crop protection and land productivity.33 While our data provide a measure of the genotype-specific quantities of microand macronutrients removed with straw harvest, long-term maintenance of soil quality will involve returning a portion of the straw residue to sustain these other aspects of crop production systems. The USDA Natural Resource Conservation Service (USDANRCS) recommendations for quantities of residue that should remain on the field to prevent soil loss from the production system are based on climate, crop management practices, soil type, and topography.13 Our data suggest that long-term maintenance of a soil environment that provides ecosystem services characteristic of a productive agroecosystem will require genotype dependent nutrient replacement. Differences in elemental composition between triticale stems, leaves, and chaff, given appropriate technology, could be exploited to reduce the quantities of elements like Si that are detrimental to thermochemical conversion while returning macro- and
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micronutrients to the production environment. One approach to accomplish this is the development of grain-harvesting equipment with the capability to separate straw components.34 Evaluation of this approach showed that selective harvest of wheat stems while returning leaves to the field reduced the quantity of Si in the harvested biomass. The elevated concentrations of Si that we measured in triticale leaf tissue relative to stem tissue suggest that a similar approach would reduce the Si content of triticale biomass and improve the utility of triticale straw for thermochemical conversion. In contrast, utilization of conventional harvest equipment would provide biomass with Si concentrations more like those measured in the composite samples used in our study. Unfortunately, as of this writing, harvest equipment that selectively collects plant component tissue is not commercially available.
’ CONCLUSIONS Differences in the concentrations of elements exist among these triticale genotypes, and between different tissues harvested from the plants. On average, harvest of triticale straw removed 9.6 g of N, 5.3 g of P, 80 g of K, and 425 g of C kg-1 of straw. Harvest of the grain alone removed 21.7, 3.1, and 4.8 g kg-1 of N, P, and K, respectively. Stem tissue contained low concentrations of Si relative to those measured in leaf tissue and chaff. The differences in Si concentrations between the tissues suggest that specialized harvest equipment with the capacity to separate stems from leaves could provide biomass that was more suitable for thermochemical conversion. The genotypic variation in the concentrations of certain minerals suggests that selections for lower concentrations of Si, K, and Cl could enhance the utility of triticale as a composite residue or selective plant components as biomass for thermochemical conversion to bioenergy.
’ AUTHOR INFORMATION Corresponding Author
*Phone: (541) 738-4125. E-mail:
[email protected].
’ DISCLOSURE Disclaimer: The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the United States Department of Agriculture (USDA) or the Agricultural Research Service (ARS) of any product or service to the exclusion of others that may be suitable. ’ ACKNOWLEDGMENT We thank Machelle Bamberger and Jennifer Young for their excellent technical help in performing the analyses. We also are grateful to Mark Larson for his efforts and expertise in facilitating the selection of the triticale lines evaluated in this study. ’ REFERENCES (1) Schwarte, A. J.; Gibson, L. R.; Karlen, D. L.; Liebman, M.; Jannink, J. Agron. J. 2005, 97, 1333–1341. (2) Mergoum, M.; Pfeiffer, W. H.; Pena, R. J.; Ammar, K.; Rajaram, S. In Triticale Improvement and Production; Mergoum, M., GomezMacpherson, H., Eds.; FAO Plant Production and Protection Paper: Rome, 2004; Vol. 179, pp 11-22. (3) Lekgari, L. A.; Baenziger, P. S.; Vogel, K. P.; Baltensperger, D. D. Crop Sci. 2008, 48, 2040–2048. 1204
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