Vernonia galamensis (Cass.) Less. produces high quantities of epoxy fatty acids useful in the reformulation of oil based (alkyd-resin) paints to reduce emission of volatile organic compounds that contribute to production of smog (Perdue et al. 1986). Other potential markets for the fatty acids include plasticizers, additives in polyvinyl chloride (PVC), polymer blends and coatings, cosmetic, and pharmaceutical applications (Carlson and Chang 1985). About 38% of the seed is oil, with about 72% vernolic acid. No other available germplasm containing naturally occurring epoxy oils, with good potential for commercialization, exists in the United States. Present needs are met with petrochemicals or by chemical epoxidation of fats and vegetable oils such as soybeans and linseed (Carlson et al. 1981). The unique structure of the vernolic acid, if left unmodified, may have a much wider use than epoxidized oils, and further epoxidation of this oil would require only about half the cost of soybean and linseed oils (Carlson and Chang, 1985).
Lesquerella fendleri (Gray) Wats. contains a seed oil high in a hydroxy fatty acid that is similar to imported castor oil, which is on the Department of Defense Critical Materials list. The United States presently spends about $40 million a year on castor imports from China, India, Thailand, and Brazil (Roetheli et al. 1991). Supply reliability and price stability are major concerns of castor oil importers and users (Roetheli et al. 1991). About 25% of the lesquerella seed is oil, of which about 55% is a hydroxy fatty acid. Castor oil is used in numerous products including adhesives, lubricants, plasticizers, pharmaceutical and medical products, waxes and polishes, soaps, inks, caulks and sealants, primers and appliance finishes, detergents, inks, and cosmetics (Roetheli et al. 1991). Lesquerella may be able to directly substitute for castor in many of these applications. Additionally, the longer fatty acid carbon chain of lesquerolic acid, compared to ricinoleic oil of castor (C20 vs. C18), could permit development of new products that would not be possible with castor. A task force of the USDA Office of Agricultural Materials has recently completed a thorough evaluation of the feasibility of commercialization of lesquerella as a new industrial oilseed crop and their conclusions were favorable (Roetheli et al. 1991).
We have concluded that low seed set following controlled self-pollinations of certain accessions, and among certain plants within other accessions is due to self incompatibility. This is most likely a genetic trait that may have a selective advantage. Even though high pollinating insect activity is observed in the field, we believe that autofertility would be most desirable for maximization of seed set in field plantings.
Another approach we are taking at the USDA/ARS, U.S. Water Conservation Laboratory, is hybridizing among subspecies and looking for favorable recombinations. The accessions we are focusing on are selections of V029 (var. petitiana), since it flowers readily under long day conditions and the seed oil content is around 40%. However, V029 is generally self-incompatible, indeterminate in flowering, and does not have good seed retention. V029 is being hybridized with V001 (var. ethiopica), which has good plant vigor, and has large seed in large seed heads (capitula) with the best seed retention of any of the germplasm in our collection. We have also identified plants of V001 that are highly autofertile. We are also interested in V013, which has not been taxonomically classified, but is from Tanzania and looks like a vigorous petitiana with a larger seed size. V013 appears to have at least partial auto-fertility, which we believe is a desirable trait. The F1 generation is now being grown in a greenhouse for evaluation along with the parents. Segregating F2 and backcross generations are being developed for selection and determination of heritability of autofertility, photoperiodic response, and possibly seed retention.
In 1989, observational plots of the different subspecies were planted at two locations, Phoenix and Yuma, Arizona. These were established by transplanting month-old seedlings into the field in mid-February. By mid-April, 100% of the plants of all varieties of the galamensis subspecies were flowering. All subspecies had 100% of the plants flowering by June 8, except for accessions of subspecies nairobensis, where the range was between 30 and 100%. Since these plants were started in the greenhouse in January, flowering was induced in most cases before field planting. These plantings gave an indication of the potential for vernonia production in temperate climates and variability in flowering habits. It also allowed for seed increase of many of the accessions.
During the 1991 growing season in Arizona, a date of planting study was conducted with accession V029 var. petitiana to determine the earliest time when vernonia can be direct seeded in the field. The earlier it can be planted without the danger of a frost, the shorter the days are for flower induction. Good stands were obtained at each planting date. Seeding rates were also tested in this experiment at 1.4, 2.8, 5.6, and 11.2 kg/ha. All except the lowest seeding rate had acceptable stands. The practice of "topping" plants was experimented with by removing the terminal buds when plants were about 0.15 m tall. This practice did not seem to enhance yields in the petitiana variety since this germplasm is shorter in stature than that of V001, where the treatment significantly enhanced yields in Zimbabwe. Some of the other subspecies may grow up to 2.8 m tall and may respond positively to topping (Anon. 1989).
The most important plant characteristics inherent to the success of vernonia domestication and production in temperate climates are day neutral flowering response, autofertility, non-dormant seed germination, good seed retention, high oil and vernolic acid content, and increased uniformity of seed maturity. In the evaluation of germplasm thus far, these characteristics appears to be present. It is matter of taking advantage of the natural genetic diversity, manipulating and recombining these traits to produce fully adapted, high yielding selections.
Other species are found throughout North America and may be grouped according to the major hydroxy fatty acid content in the seed oil. These three groups are: lesquerolic acid species, C20:1-OH (western United States), densipolic acid species, C18:2-OH (east of the Mississippi), and auricolic acid species, C20:2-OH (Texas and Oklahoma) (Roetheli et al. 1991). If production and commercialization are successful for L. fendleri, domestication of other species for production of densipolic and auricolic acid is likely to be feasible in adapted areas.
The most successful method of planting has been with a broadcast Brillon seeder. This type of seeder is readily available to farmers that grow such crops as alfalfa and clovers, and thus, would not involve additional expenses. We compared this method with row type vegetable planters and found it superior due to the even seed distribution and the easy adjustment of rate setting for desired plant populations. Although the row plantings had more plants per square meter area, the broadcast plantings had higher yields. Plants were better distributed throughout the field when broadcast planted and were able to develop better. Yields were higher as a consequence when compared to being planted in a crowded row.
We found no significant differences in yields between planting on raised beds and level fields. The advantage of raised beds is in weed and insect control, and, if water quality is a problem, salts are easier to manage. The disadvantage of the raised bed method is the difficulty of harvesting. Dried plants tend to lodge down into the furrow at harvest, making them difficult to recover with the combine. Slight modification to the combine could solve this problem. We are currently experimenting with 0.5, 0.75, and 1 m (20, 30, and 40 inch) bed widths. The shallower furrow of narrow beds may minimize combine difficulty. Higher plant populations were obtained on a raised bed compared to the level basin method. Seeding rates of 4.5, 6.75, and 9.0 kg/ha were compared for both treatments. The yields from the 6.75 kg/ha rate were the highest, but this was not statistically significant in the one year test. Once a desirable plant population is reached, a higher population may not significantly contribute to yield. Planting rate also depends on the seed quality and germination. L. fendleri does not have a seed dormancy problem as is the case with many of the other lesquerella species.
Breeding improvements are focused on developing lines with higher oil content. Another trait of interest includes earlier flowering so the growing season takes place before the onset of high temperatures when consumptive use of water is the highest, so water is conserved. We have selected and produced yellow seeded lines. Lesquerella seedcoats are normally orange-brown in color. Since pigmentation of the seed oil is a slight problem, it may be overcome if the seed coat did not contain this darker pigment. Oil content may also be higher in these lines as was found in rapeseed and flax because of the thinner seed coat (Knowles 1983). This remains to be tested.
Pollination mechanisms are being investigated. We have observed that our large acreage plantings were not as productive as smaller research plots. This could be attributed to a lack of adequate number of bees and insect pollinators for optimum seed set in large populations. We believe that for lesquerella to be fully successful, autofertility must be incorporated. We are presently attempting to select for this trait. We have identified a number of male-sterile lines, and are currently studying the mode of inheritance. These may be useful for hybrid seed production in the future.
In the 1990-91 season, the initiation of a cooperative venture took place between two private industrial companies, Agrigenetics Company and the Jojoba Growers and Processors, Inc., USDA/ARS, and the University of Arizona. Eight hectares of lesquerella were planted on the University of Arizona, Maricopa Agricultural Center in central Arizona. The seed oil harvested from this planting is being used to formulate products for testing. Research on processing methodology and utilization is being conducted at the USDA/ARS National Center for Agricultural Utilization Research (NCAUR) Peoria, IL. The meal is being evaluated in mice and chick feeding trials at Kansas State University and in cattle feeding trials at the University of Arizona. Approximately 30 ha have been planted by farmers in California, Arizona, Texas, and Oklahoma in 1991-92 for increased pilot scale production and utilization. These fields will be in addition to the agronomic and breeding research plots that have been planted in Arizona, Texas, and Oregon.
| Avg. no. filled seeds/head for 5 plants | ||||||
| Accession | Ssp./Variety | 1 | 2 | 3 | 4 | 5 |
| V001 | galamensis ethiopica | 0 | 0 | 2.6 | 17.5 | 36 |
| V008 | galamensis australis | 0 | 0.4 | 5.3 | 10 | 16.2 |
| V009 | galamensis australis | 0 | 0 | 0 | 1.4 | 7.4 |
| V004 | galamensis galamensis | 0 | 0 | 0.8 | 1.3 | 2 |
| V003 | galamensis galamensis | 0 | 0 | 0 | 0 | 0 |
| V013 | galamensis petitiana | 3.1 | 6.3 | 8.8 | 9.3 | 10.4 |
| V020 | afromontana | 0 | 0 | 0 | 0.8 | 8.8 |
| V021 | gibbosa | 0 | 0 | 0 | 0 | 0.2 |
| V022 | gibbosa | 0 | 0 | 0 | 1.5 | 2.2 |
| V018 | mutomoensis | 0 | 0 | 0 | 0 | 0.1 |