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Carr, P.M. 1993. Potential of fanweed and other weeds as novel industrial oilseed crops. p. 384-388. In: J. Janick and J.E. Simon (eds.), New crops. Wiley, New York.

Potential of Fanweed and Other Weeds as Novel Industrial Oilseed Crops*

Patrick M. Carr

  1. METHODOLOGY
    1. 1990
    2. 1991
  2. RESULTS AND DISCUSSION
    1. Fanweed
    2. Black Mustard
    3. Wild Mustard
    4. Hare's Ear Mustard
    5. Euphorbia lagascae
    6. Weed Control
  3. SUMMARY
  4. REFERENCES
  5. Table 1
  6. Table 2
  7. Fig. 1
Diversification has been suggested as a possible strategy for improving the financial condition of United States crop producers (Jolliff and Snapp 1988; Jolliff 1989). Agricultural production of industrial feedstocks, for example, would open additional markets to farmers who typically grow only food and feed crops. In some instances, farm production of industrial feedstocks could be quite profitable since high-value specialty chemicals are contained in the seeds of some plants (Hinman 1986).

While crambe, (Crambe abyssinica Hochst.), ironweed [Vernonia galamensis (Cass.) Less.], and several other plant species have been identified as promising industrial crops (Princen 1983), few studies have evaluated the potential of present weed species as sources of high-value specialty chemicals and industrial feedstocks (Clopton and Triebold 1944; Shultz et al. 1983). There are several weeds that are well adapted to growing conditions in different regions of the United States and could be grown as sources of industrial chemicals if domesticated. While a plant may contain desirable chemicals or have valuable properties, it is unknown if these plant species could be developed for field production. The objective of this research was to evaluate the agronomic potential of four weeds occurring in the Northern Great Plains: fanweed [Thlaspi arvense (L.)], black mustard [Brassica nigra (L.) Koch], wild mustard [Brassica kaber (DC.) Wheeler], and hare's ear mustard [Conringia orientalis (L.) Dumort]. These four weeds were studied since previous work indicated that each contained valuable specialty chemicals (Appelqvist 1971), or were related to other plant species which were sources of valuable chemicals. The potential of Euphorbia lagascae Spreng., as a field crop was also considered since past research indicates it may have potential as an industrial crop (Krewson and Scott 1966), even though this plant species is neither native to, nor naturalized in, the United States.

METHODOLOGY

1990

A field evaluation was conducted under dryland management at the Carrington Research/Extension Center (47°30' N, 99°7' W) in central North Dakota. Seed samples of a single accession of black mustard, hare's ear mustard, and Euphorbia lagascae were obtained from the USDA/ARS National Center for Agricultural Utilization Research in Peoria, Illinois, while seed of wild mustard and fanweed were collected from wild stands. Seed of each species along with crambe, an industrial crop which is grown in North Dakota, was planted in nonreplicated 1.4 m2 plots on May 17. The agronomic potential of each species was rated on the basis of its ease of establishment, rate of growth, initiation and duration of flowering, susceptibility to lodging and pests, seed development (determinate or indeterminate), susceptibility of seeds to shatter, and other factors. Height of 10 plants of each species was measured prior to harvest. A 0.7 m2 area was harvested by hand for determination of dry matter, grain yield, and seed weight.

1991

The six plant species included in the 1990 field experiment were each planted in 8.2 m2 plots in a randomized complete block design with four replicates. The agronomic potential of each plant species was evaluated as described. A sunfleck ceptometer (Decagon Devices, Inc., Pullman, WA) was used to quantify the amount of photosynthetically active radiation (PAR) that was intercepted by the plant canopy in plots of two replicates on selected dates during the growing season. Plants in a 1.9 m2 area from the central portion of each plot were harvested for determination of dry matter, grain yield, and seed weight. Seed oil content and fatty acid distribution of the oil were determined for a representative sample of each species by mass spectroscopy at the Food and Cereal Science Laboratory at North Dakota State University, in a manner previously described (Riveland 1991).

RESULTS AND DISCUSSION

Fanweed

Fanweed (syn. stinkweed, field pennycress, pennycress) was rated as having excellent potential as a new crop if established in the fall (Table 1). Poor germination of spring-sown fanweed seed was a problem. As a result, yield of fanweed was low when planted in the spring. Metzger (1990) reported that exposure to temperatures of 0° to 10°C for 3 to 6 weeks can break the dormancy of fanweed seed. Dormancy can be broken if seed is scarified by scratching the seedcoat (Best and McIntyre 1975), although this was not true for spring-sown seed in this study. Broadcast planting rather than seed drilling is desirable, since exposure to light seems to enhance seed germination. Overwintering fanweed plants were in full-flower by mid-May, while other plant species were still seedlings. Hence, seed production by most fanweed plants was completed prior to the relatively hot, dry conditions which developed by mid-July during 1990 and 1991.

Seeds, contained in pods, tended to shatter as plant moisture levels declined; however, plants could be swathed to minimize harvest loss from shattering and to promote uniform seed maturation. If swathed, fanweed could be harvested in mid-June in the Northern Great Plains, possibly enabling a second crop to be planted in the field during the same growing season. Double cropping would likely be possible in more southern portions of its range in North America.

Individual fanweed plants established in the fall produced an average of 1,600 seeds, translating into an estimated yield of about 1,500 kg/ha for both years. This yield is similar to that reported in Montana during the 1940s when fanweed was experimentally grown under irrigated management (Clopton and Triebold 1944), and to seed production estimates of wild stands in Canada (Best and McIntyre 1975). Seed yields in excess of 1,300 kg/ha are not unusual when seed from wild fanweed stands is grown in the northern United States.

Fanweed demonstrated potential as an industrial crop on the basis of seed oil content and composition (Table 2). Fanweed seed contained about 26% oil by weight; the oil, in turn, was close to 40% erucic acid (22:1). Erucic acid is an unusual fatty acid with several industrial applications (Van Dyne et al. 1990). While the level of erucic acid in the seed produced by crambe was greater than that produced by fanweed, consideration of pests, crop rotations, and other factors could make fanweed a promising candidate for new crop development.

Black Mustard

Black mustard was rated as having very good to excellent agronomic potential. Plants were easy to mechanically sow and manage. Growth was vigorous and large plants developed (Table 1). Seed production was underway by early July; the seeds which developed were contained in pods from 1.3 to 1.9 cm long which tended to shatter as plant moisture levels declined. Plants would probably need to be swathed prior to harvesting. Black mustard may fit as a short season crop in some crop rotations in the Northern Great Plains.

Black mustard produced relatively large amounts of seed (>1,200 kg/ha) during 1990 and 1991 (Table 1). In 1991, close to 1,900 kg/ha of seed was produced, making black mustard the highest yielding species evaluated. By comparison, yield of crambe averaged 1,820 kg/ha in 1991. Unlike fanweed, seed dormancy was not a serious problem with black mustard, so relatively good plant stands were fairly easy to establish in the spring.

Black mustard produced seed that was 32% oil (Table 2). Of this, roughly 40% was erucic acid. As with fanweed, black mustard demonstrated potential as an industrial crop, even though crambe seed contained greater amounts of erucic acid.

Wild Mustard

Wild mustard (charlock, kaber mustard) was considered to have very good to excellent agronomic potential. Plants were easy to mechanically sow and manage, and seeds appeared to lend themselves to mechanical harvesting methods. As with fanweed and black mustard, seeds of wild mustard were susceptible to shattering so plants would probably be swathed prior to harvesting the seed if grown on a field-scale.

Wild mustard produced roughly 2,000 kg/ha of seed during 1990 and 1991 (Table 1). Individual plants produced an average of 2,076 seeds which were contained in pods approximately 2.5 cm in length. The seed contained about 26% oil but failed to be comprised of a high percentage of highly valued fatty acids (Table 2). For this reason, wild mustard was considered to have low potential as an industrial crop.

Hare's Ear Mustard

Hare's ear mustard (syn. hare's mustard) was considered to have moderate agronomic potential. Plants were generally easy to mechanically sow and manage. However, about 15% of the stand was destroyed by an unknown pathogen in 1991. Plants were short (<40 cm) and some seed pods were less than 10 cm above the soil surface (Table 1). This could present difficulties in the mechanical harvesting process. Seed could be harvested without first swathing the plants since seed pods were not susceptible to shattering.

Hare's ear mustard produced relatively low quantities of seed in 1990 and 1991 field evaluations; yields averaged 901 kg/ha in 1990 and only 549 kg/ha in 1991 (Table 1). Individual plants produced an average of 590 seeds which were contained in seed pods about 5 cm in length.

Hare's ear mustard produced seed containing about 30% oil, with close to 30% of the oil being comprised of erucic acid (Table 2). Other research indicates that the oil contains additional fatty acids with industrial applications (Appelqvist, 1971). It seems that further consideration of hare's ear mustard as an industrial crop is warranted.

Euphorbia lagascae

Euphorbia lagascae was considered to have the lowest agronomic potential of all plant species. Seed development was indeterminate and fruits containing the seed burst violently as the seed approached maturity. Still, this plant species was agronomically attractive in several respects. The seed was large and easy to mechanically sow. Seedlings grew rapidly and were easy to manage. Grasshoppers and other insect pests did not appear to feed on Euphorbia lagascae. Improvements in seed retention are needed.

Euphorbia lagascae produced an abundance of seed in 1990 and 1991 field evaluations, but much of the seed could not be collected due to seed shattering. Hence, harvested seed only amounted to about 200 kg/ha during 1990 and 150 kg/ha during 1991 (Table 1). Further studies are needed to assess seed yields when plants are swathed prior to harvesting.

Euphorbia lagascae produced seed which contained over 50% oil by weight. Past research determined that the oil contained over 50% vernolic acid (K. Carlson 1991 pers. commun.), making it a promising candidate for new crop development if genetic improvements and/or management practices could enhance the mechanical harvestability of seed.

Weed Control

Weeds were a problem and had to be removed by hand throughout the growing season. Effective weed control strategies must be developed for each plant species. The plant canopy produced by crambe intercepted more than 90% of the incident PAR after June 13 in the 1991 field evaluation (Fig. 1). Only small amounts of PAR could penetrate the canopy after this date and reach weed seedlings which were developing underneath. This may explain why weed pressure was much greater in hare's ear mustard than in crambe plots, since more than 50% of the incident PAR reached weed seedlings developing under a canopy of hare's ear mustard through most of the growing season.

SUMMARY

Fanweed, black mustard, hare's ear mustard, and Euphorbia lagascae contain fatty acids with important industrial applications. These plants have varying degrees of potential as novel industrial crops. Fanweed is adapted to growing conditions in the Great Plains and seems suited to field production methods. Approximately 1,500 kg/ha of seed was produced in 1990-91 field evaluations in North Dakota. This seed contained about 180 kg/ha of erucic acid, an unusual fatty acid with several industrial uses. Black mustard and hare's ear mustard also produced seed containing erucic acid, but these weed species appeared to have less potential than fanweed as industrial crops when agronomic factors were considered. Seed harvesting difficulties with Euphorbia lagascae and failure of wild mustard seed oil to contain high-value fatty acids presently limit their potential as industrial crops.

REFERENCES

*Sincere appreciation is extended to R. Kleiman, research leader for new crops and K. Carlson, a research chemist, both at the USDA/ARS National Center for Agricultural Utilization Research, for providing seed, seed oil composition data, and helpful advice, and to N. Hettiarachchy, Associate Professor of Cereal Science and Food Technology at North Dakota State University, for determining the seed oil content and composition of the plant species included in this investigation.

Table 1. Selected agronomic characteristics of weed species evaluated during 1990 and 1991 in central North Dakota.

Date established Duration of flowering Lodgingz Plant ht (cm) Seed yield (kg/ha) Seed weight (g/100 seed)
Plant 1990 1991 1990 1991 1990 1991 1990 1991 1990 1991 1990 1991
Fanweed June 19 May 13 July 15- Aug 13 June 7- July 1 0.5 0.5 43 27 200 119 0.09 0.07
Sept 1 Aug 25 May 20- June 15 May 13- June 15 0.5 0.5 28 67 1628 1414 0.08 0.08
Black mustard May 27 May 10 June 29- Aug 8 June 13- Aug 20 1.0 1.0 176 126 1243 1875 0.17 0.16
Wild mustard May 27 Apr 29 June 8- July 26 June 5- Aug 14 1.0 1.0 67 83 2005 1849 0.24 0.25
Hare's ear mustard June 11 May 26 July 9- July 29 June 3- July 21 1.0 1.0 37 27 901 549 0.16 0.19
Euphorbia lagascae May 29 May 15 July 6- Sept 20 June 12- Sept 28 1.0 1.0 72 42 201 147 0.91 1.18
Crambe May 24 Apr 26 June 26- July 31 June 1- July 29 1.0 1.0 89 61 1997 1820 0.64 0.62
z0 = none, 1 = severe.

Table 2. Fatty acid acid composition of the seed oil.

Fatty acid composition (% of total seed oil)
Plant 16:0 18:0 18:1 18:2 20:0 22:1
Black mustard 4.8 0.0 14.3 17.9 14.0 37.6
Wild mustard 3.9 2.2 35.7 22.7 17.6 6.4
Crambe 1.4 0.8 14.0 6.2 1.0 62.9
Fanweed 2.7 0.0 13.8 20.2 9.0 37.8
Hare's ear mustard 2.5 0.0 5.8 27.5 2.2 26.9

Fig. 1. Percent of photosynthetically active radiation intercepted by the plant canopy.
Last update September 12, 1997 aw