Vernonia oilseed production in the mid-Atlantic region of
the United States
H.L. Bhardwaj
a,*, A.A. Hamama
a, M. Rangappa
a, D.A. Dierig
baAgricultural Research Station,Virginia State Uni6ersity,PO Box 9061,Petersburg,VA 23806, USA bUSDA-ARS,US Water Conser6ation Laboratory,Phoenix,AZ 85040, USA
Received 1 November 1999; accepted 19 March 2000
Abstract
Epoxidized oils, manufactured by chemical epoxidation of fats and vegetable oils such as soybean [Glycine max(L.) Merr.], are useful in reformulation of oil based (alkyd-resin) paints to reduce emissions of volatile organic compounds that contribute to production of smog. Other potential markets for epoxy fatty acids include plasticizers, additives to polyvinyl chloride, polymer blends and coatings, cosmetic, and pharmaceutical applications. Currently, no oilseed crop has been commercialized as a source of natural epoxidized oils. However,Vernonia galamensis(Cass.) Less. has been identified to have potential for domestication as a new industrial oilseed source of natural epoxy fatty acids. The main objective of this research was to evaluate feasibility of vernonia production in mid-Atlantic region of the United States. Specifically, we wanted to evaluate available vernonia germplasm for seed yield, oil content, and oil quality, and to determine suitable production practices. The seed yield (kg/ha) in field experiments conducted from 1994, 1995, and 1996 at Randolph Farm of Virginia State University (37°15%N and 77°30.8%W), with a selected group of vernonia lines, ranged from 490 to 1288, 494 to 1394, and 1070 to 1934, respectively. Oil content ranged from 30.2 to 36.7% and 32.1 to 39.2%, respectively for 1995 and 1996 and the vernolic acid content ranged from 68.9 to 74.7% and 69.1 to 75.6%. A significant positive correlation (r=0.34) between oil content and vernolic acid content indicated that both these characteristics could be improved simultaneously. The highest seed yield was obtained with 100 kg N/ha. A pre-plant-incorporated application of Trifluralin herbicide at 0.5 kg/ha a.i. did not reduce vernonia stand establishment. Seedhead shattering was observed to be a limitation in the evaluated vernonia germplasm. These results indicate that commercial vernonia production in Virginia and other areas in the mid-Atlantic region of United States may be feasible. © 2000 Elsevier Science B.V. All rights reserved.
Keywords:Vernonia anthelmintica;Vernonia galamensis; Vernolic acid; Oil content
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Contribution of Virginia State University Agricultural Research Station, Journal Article Series No. 217. The use of any trade names or vendors does not imply approval to the exclusion of other products or vendors that may also be suitable.
* Corresponding author. Tel.: +1-804-524-6723; fax: +1-804-524-5950. E-mail address:hbhardwj@vsu.edu (H.L. Bhardwaj)
1. Introduction
During the mid-1950s, the Agricultural Re-search Service, US Department of Agriculture initiated a plant screening program to identify new and unique plant constituents as sources of
industrial raw materials that would not compete with existing crops. A component of this program focused on finding unusual seed oils such as ver-nonia [Vernonia anthelmintica(L.) Willd.] with an epoxidized fatty acid because substantial quanti-ties of epoxy oils are used by industry.
Table 1
Performance of ten vernonia genotypes at Petersburg, Virginia for 1994
Seed yield (kg/ha)
Seed heads per plant Height (cm)
Entry
Mature (%) Immature (%)
26 bca
Mean 71 110 796
8
25 38
61 CV
aMeans followed by same letter, within columns, were not different according to Duncan’s multiple range test (P=0.05).
Table 2
Performance of vernonia lines for 1995 and 1996 at Petersburg, Virginia
Seed oil content (%)
Entry Seed yield (kg/ha) Vernolic acid content of seed oil
(%)
Mean
1995 1996 1995 1996 Mean 1995 1996 Mean
1542 a AZ95-2 751 cd 1737 a
1315 ab 1243 a 1279 a 30.3 c 38.1 a 34.2 a 69.6 de 75.3 a
1204 33.7 36.2 35.0
Mean 861 1546 71.9 73.6 72.7
40
CV 32 35 6.4 7.5 7.1 2.1 2.7 3.0
Table 3
Correlation coefficients among vernonia traits grown at Peters-burg, Virginiaa
1996
Traits 1995 Combined
−0.05
Seed yield and oil −0.07 0.10 content
0.03 Seed yield and −0.24 0.04
vernolic acid content
Oil and vernolic acid −0.01 0.52** 0.34* content
a*, **: Correlation coefficient significantly different from zero at the 5 and 1% level, respectively.
to American agriculture. A program was also initiated to conduct utilization research on ver-nonia oil. The breeding and agronomic research led to the development of improved lines, but as a result of lack of seed retention and non-uniform maturity of seed heads, the program was discon-tinued (Massey, 1971). Even though utilization research indicated potential for success, the lack of vernonia varieties suitable for cultivation in the United States led to the cessation of agronomic and utilization research by the early 1970s (Perdue et al., 1986).
Interest in vernonia was rekindled when Ver -nonia galamensis (Cass.) Less. was discovered in 1964 in Ethiopia (Perdue et al., 1986). Vernonia galamensis is a herbaceous annual plant that is widely distributed in regions of East Africa. This species exhibited increased seed retention com-pared to V. anthelmintica. The seeds of V. gala
-mensis contained about 42% oil with a 73%
vernolic acid content, substantially higher than that of best V. anthelmintica selections (Thomp-son et al., 1994a). However, short-day response flowering limited the usefulness of this species in the United States. The discovery of a day-neutral germplasm in one accession of V.galamensisssp. galamensisvar.petitiana(Thompson et al., 1994b) greatly improved its potential use. However, this accession (A0399) lacked important characteris-tics such as seed retention, which limited its usefulness.
The main objective of our research efforts was to evaluate the feasibility of vernonia production in mid-Atlantic region of the United States. Spe-cifically, we wanted to evaluate available vernonia germplasm for seed yield, oil content, and oil quality. Preliminary research was also conducted to identify suitable production practices.
2. Materials and methods
Field experiments were conducted at the Randolph Farm of the Virginia State University (Latitude 37°-15%N, Longitude 77°-30.8%W). The soil type was Abel sandy loam (Fine Loamy mixed, thermic Aquatic Hapridult). This region is charac-terized by short days when vernonia starts to flower.
Table 4
Effects of fertilizer rates on vernonia yield in Virginia
Rate (kg/ha) Yield (kg/ha)
Potassium 50 1160.0 a
1178.3 a 100
150 1205.4 a
aMeans followed by the same letter, within each fertilizer, were not different according to Duncan’s multiple range test (P=0.05).
Vernonia produces high quantities of epoxy fatty acids that are useful in reformulation of oil based (alkyd-resin) paints to reduce emissions of volatile organic compounds that contribute to production of smog (Anonymous, 1989). Other potential markets for epoxy fatty acids include plasticizers, additives to polyvinyl chloride, poly-mer blends and coatings, and cosmetic and phar-maceutical applications. 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 soybean [Glycine max (L.) Merr.].
2.1. Germplasm e6aluation
During 1994, nine breeding lines and a bulk population of A0399 were evaluated. Breeding lines with the ‘AZ’ designation were hybrids formed by recombining the day neutral flowering response of A0399, var. petitiana, with the desir-able plant growth characteristics of var. ethiopica and other accessions ofV.galamensis(Thompson et al., 1994b). The nine progenies (1 – AZ94-9) and A0399 as a check were planted in a green-house on 22 April 1994 in flat trays. A commercial potting material, Promix-B, was used as the planting medium. The early-germinating and healthy plants were transplanted to individual cells in speedling trays on 20 May 1994. The seedlings were transplanted to the field on 8 June 1994. A randomized complete block design with four replications was used for field planting. The spacing between plants was 0.3 m and that be-tween rows was 0.9 m. Each plot consisted of four rows with 12 plants per row. All plots received 100 kg/ha each of nitrogen, phosphorus, and potassium. Four plants per plot were harvested to determine the proportion of mature and immature seed heads per plant. The seed yield from mature seedheads of each plot was used to calculate seed yield (kg/ha). A sample of 25 mature seedheads was also taken from each plot.
During 1995 and 1996, 11 selections from the United States Water Conservation Laboratory, Phoenix, Arizona, two selections from Virginia, and a check were evaluated. These 14 lines were planted in a randomized complete block design with four replications on 16 May 1995 and 21 May 1996, respectively, at the Randolph Farm of Virginia State University. Each plot consisted of four rows spaced 75 cm apart and 4.2 m long. A total of 1 g of seed was direct-seeded in each individual row. The middle two rows were har-vested by hand for yield measurements.
2.2. Fertilizers
Acid-delinted seed of A0399 were planted in pots on 28 June 1993, in the greenhouse to obtain enough seedlings for the nitrogen, phosphorus, and potassium field experiment. After planting (14
days), single seedlings were transplanted to indi-vidual cells in plastic trays. Vigorous transplants from these cells were transplanted to the field on 21 July 1993 in 28 plots. Each plot consisted of three rows 3 m long and 75 cm apart with 30 cm between plants in the row. The field was lightly irrigated (about 1 cm water) 1 day before trans-planting to assist with seedling establishment. These plots were irrigated immediately after trans-planting and for the following 2 days with ap-proximately 1 cm water. Three rates each of nitrogen, phosphorus, and potassium (50, 100, and 150 kg/ha) were applied (27 combinations) on 17 August 1993. One plot was treated as a check and did not receive any fertilizer treatment. The field design was a randomized complete block design with two replications (28 plots per replica-tion). A soil sample from this field indicated that residual nitrogen was approximately 14 kg/ha. The experimental area had very high content of P (approximately 200 kg/ha) and high content of K (approximately 140 kg/ha). The organic content and the pH of the experimental area were approx-imately 1.2 and 6.3, respectively. In this experi-ment, mature seed heads from the middle row of each plot were harvested in November.
2.3. Herbicides
(0.2 kg/ha a.i. for Poast and 0.3 kg/ha a.i. for Reflex). Only visual observations on foliar dam-age were recorded to determine whether the herbi-cide application had caused damage to the plant canopy.
3. Results and discussion
3.1. Germplasm e6aluation
Significant variation existed among the entries for plant height, mature and immature seed heads, seed yield, and plant height during 1994 (Table 1). The plant height ranged from 83 to 126 cm. The seed yield ranged from 490 to 1288 kg/ha with a mean of 796 kg/ha. The yield of the check line (A0399) was 880 kg/ha, which was not signifi-cantly different from that of the highest yielding entry (AZ94-8), which had a seed yield of 1288 kg/ha. AZ94-6 had a significantly higher percent-age of mature seedheads compared to A0399.
The 1995 – 1996 vernonia research evaluating 14 lines (11 from Arizona, two from Virginia, and a standard check), strongly suggests that this unique oilseed plant is adapted to Virginia condi-tions and it may be feasible to grow this plant in the mid-Atlantic region of the United States. There were indications that fresh-unripened seeds of some selections from Arizona had poor germi-nation. The yield, oil content, and vernolic acid content data are presented in Table 2. The seed yield ranged from 494 to 1394 kg/ha with four lines (AZ95-1, AZ95-3, AZ95-5, and AZ95-6) sig-nificantly outyielding A0399 (599 kg/ha) during 1995, indicating that progress has been made to improve vernonia germplasm for yield. The yield of the two Virginia lines (VX95-1 and VX95-2) during 1995, though not significant, was numeri-cally superior to that of A0399. The oil and vernolic acid content in 1995 ranged from 30.3 to 36.7% and 68.9 to 74.7%, respectively. None of the breeding lines differed significantly from A0399 for oil or vernolic acid contents. In 1996, the yield, oil content, and vernolic acid content data indicated a lack of significant variation among the 14 entries for these traits (Table 2). The yield ranged from 1070 to 1934 kg/ha, the oil
content from 32.0 to 39.2%, and the vernolic acid content from 69 to 76%. Analysis of combined data from 1995 to 1996 (Table 2) indicated a lack of significant variation among the 14 entries for yield and other traits.
These production levels compare favorably with the vernonia seed yield of 1200 kg/ha in Zim-babwe (Perdue et al., 1987). Seed shattering con-tinued to be prevalent in the available vernonia germplasm in our tests. However, based on the seed yield of 1546 kg/ha for 1996, the oil content of 36% (Table 2), and the high demand for ver-nonia oil, commercial verver-nonia production in Vir-ginia and other areas in the mid-Atlantic region of the United States may be economically feasible.
The correlations between various characteristics are presented in Table 3. Correlations between seed yield and oil content, and that between seed yield and vernolic content in the oil were not significant. The correlation between oil content and vernolic acid content in the oil was significant and positive, based on the 1996 data (+0.52) and the combined data from 1995 and 1996 (+0.34). These results indicate that it might be possible to simultaneously increase the oil yield and vernolic acid yield of V.galamensis.
3.2. Fertilizers
The results (Table 4) indicated that highest seed yield was obtained with 100 kg/ha of nitrogen fertilizer rate. The seed yields following 50, 100, and 150 kg/ha of nitrogen fertilizer were 946, 1298, and 1300 kg/ha, respectively. The residual nitrogen in this field was approximately 14 kg/ha. Therefore, nitrogen requirement for vernonia is approximately 114 kg/ha. The results also showed that vernonia seed yield did not increase when P and K rates were increased from 50 to 100 or 150 kg/ha. Based on this data, it is not possible to determine the lower acceptable rates for P and K fertilizers. However, P and K fertilizers at the rates of approximately 50 kg/ha may be suitable.
3.3. Herbicides
establishment (data not shown). This observation is similar to the results in Oregon (Roseberg, 1997). Therefore, trifluralin seems to be an excel-lent candidate for registration for weed control in vernonia. Visual estimates of foliar injury indi-cated that selections differed in their tolerance to Poast and Reflex herbicides (Data not shown). Foliar injury following treatment with Reflex was considered unacceptable, and, thus, unsuitable for weed control in vernonia. Further research is needed for Poast herbicide to identify precise ap-plication times and rates.
References
Anonymous, 1989. Vernonia, new industrial oil crop. Agric. Res. 37 (4), 10 – 11.
Massey, J.H., 1971. Harvesting Vernonia anthelmintica (L.) Willd. to reduce seed shattering losses. Agron. J. 63, 812. Perdue, R.E. Jr, Carlson, K.D., Gilbert, M.G., 1986. Ver -nonia galamensis, potential new crop source of epoxy acid. Econ. Botany 40 (1), 54 – 68.
Perdue, R.E. Jr, Jones, E., Nyati, C.T., 1987. Vernonia gala -mensis: a promising new industrial crop for the semi-arid tropics and subtropics. In: Wickens, G.E., Haq, N., Day, P. (Eds.), New Crops for Food and Industry. Chapman and Hall, New York, pp. 197 – 207.
Roseberg, R.J., 1997. Herbicide tolerance by vernonia grown in temperate zone. Ind. Crops Prod. 6, 89 – 96.
Thompson, A.E., Dierig, D.A., Kleiman, R., 1994a. Varia-tion inVernonia galamensisflowering characteristics, seed oil and vernolic acid contents. Ind. Crops Prod. 3, 175 – 183.
Thompson, A.E., Dierig, D.A., Johnson, E.R., Dahlquist, G.H., Kleiman, R., 1994b. Germplasm development of Vernonia galamensis as a new industrial oilseed crop. Ind. Crops Prod. 3, 185 – 200.
