The passage of the Dietary Supplement Health and Education Act in 1994 made the use of supplements more acceptable in the U.S., increasing demand for botanicals to use in health care and maintenance. These botanicals, primarily medicinal and aromatic plants, currently represent about 25% of the dietary supplement market in the U.S. Although much of the market for botanicals traditionally has been met through collection of plants in the wild, enhanced cultivation of several species will be essential to bring standardized, quality plant materials into the marketplace.
Lyle E. Craker and Zoë Gardner
Giuliana Mulas and Lyle E. Craker
Variation in light quality is known to modify plant morphology, growth, and chemical constituency in plants. In the present study, the effect of light quality on growth and essential oil composition in rosemary (Rosmarinus officinalis L.) was investigated by comparing plants receiving supplemental red (660 nm) and far-red (730 nm) with each other and with control plants not receiving supplemental light. Except for the supplemental light treatments, all plants were grown under natural light conditions in a greenhouse and received full daylight, averaging 9.23 h/day during the study. The red and far-red light treatments, given as day extensions, started daily 15 min before sunset and continued for 4 h each evening for 4 weeks. No significant differences were observed in biomass yield from the different light treatments, but far-red light caused elongation of internodes and a reduction in the number of leaves in comparison with control and red-light treated plants. Essential oil production was highest in plants grown under far-red light treatments.
Megan McCollom*, Stefan Gafner, and Lyle E. Craker
Maca (Lepidium meyenii Walp.), a root crop similar to radish, has been consumed in Peru for thousands of years as a food and medicine. Medicinally, the plant is used to increase human and livestock stamina and to ameliorate fertility problems associated with living at the high elevations in which the plant grows. The reputation of maca as a fertility and libido enhancer has increased the popularity of the plant in the United States and other Western countries. Constituents of interest in maca include fatty acids and macamides, but to evaluate the quality of maca products and raw material, fatty acid and macamide standards are required. While fatty acid standards are obtainable, macamide standards are not commercially available. In this study, one major macamide, n-benzylhexadecanamide, was synthesized with high yields using benzylamine and palmitoyl chloride as starting materials. The process, which was a relatively easy, one-step synthesis, could be used also to obtain other macamides without going through a time-consuming isolation. The major macamides in extracts of dried, ground maca sourced from vendors in the United States and Peru were identified and quantified by LC-UV/MS using n-benzylhexadecanamide as a standard compound.
Z.Y. Mao and Lyle E. Craker
Mulch, light level, and nitrogen fertilization were tested for their effects on productivity of horehound (Marrubium vulgaris L.). Yield of this plant increased under mulched conditions and with the addition of nitrogen fertilizer. Yield decreased with reduced light levels. Productivity of individual plants correlated with the number of branches per plant, leaf size, and leaf chlorophyll content. The number of branches per plant decreased with increased shading, but increased with increased nitrogen fertilization. The influence of mulch and shading on productivity could be due to the changes in soil temperature and in soil water potentials. Full-sun, high nitrogen, and mulch are suggested for optimum field production of horehound.
Yuan-Hai Zhang and Lyle E. Craker
Air pollution may play a role in gametophytic selection. To estimate whether such selection was occurring, pollen grains from homozygous and heterozygous tomato plants were tested under pollution stress. Homozygous pollen could be expected to respond to pollution more uniformly than heterozygous due to the identical genotype of the pollen grains. Acid rain reduced pollen germination and tube elongation in Lycopersicon hirsutum LA1777 (heterozygous) and Lycopersicon pennellii LA716 (nearly homozygous). UV-B reduced tube length of the pollen from both plants, but ozone only reduced pollen tube length of L. pennellii. The responses of these two kinds of pollen to acid rain, ozone, and UV-B appears to be same in terms of heterozygosity and stress dosages, suggesting the reduction of pollen germination and tube elongation under pollution stress may be mediated through physiological or physical alterations and not a response of different genotypes.
Thomas H. Boyle, Lyle E. Craker, and James E. Simon
Plants of rosemary [Rosmarinus officinalis L. (Lamiaceae)] were grown in pots containing a soilless (1 sphagnum peat:1 perlite) or soil-based (1 sphagnum peat: 1 perlite:1 field soil) growing medium and fertilized with either 12N-5.2P-12.5K controlled-release fertilizer (CRF) at 9.0 g/pot; constant liquid fertilization (LF) with 20N4.3P-16.7K at 150 mg N/liter; constant LF at 150 mg N/liter, plus CRF at 4.5 g/pot; weekly LF at 150 mg N/liter; or weekly LF at 150 mg N/liter, plus CRF at 4.5 g/pot. Constant LF plus CRF generally reduced plant height and depressed shoot fresh weight relative to other fertilizer regimes. Essential oil content was highest in plants receiving weekly LF. Plants grown in the soil-based mix were shorter, shoot fresh and dry weight tended to be lower, and essential oil yield was higher when compared to plants grown in the soilless mix. Satisfactory growth was obtained in both media when rosemary plants were fertilized with 12N-5.2P-12.5K CRF at 9.0 g/pot or weekly LF with 20N<.3P-16.7K at 150 mg N/liter.
Zoë E. Gardner, Lorna Lueck, and Lyle E. Craker*
Black cohosh [Actaea racemosa L.; syn. Cimicifuga racemosa (L.) Nutt], a plant native to the eastern United States, is believed to have been used as a medicinal by Native Americans for thousands of years. Currently, the root of the species is popular as a herbal remedy for the relief of menopausal symptoms. Recent estimates suggest that over 90% of the black cohosh sold is collected from the wild, resulting in an unsustainable harvest of ≈9 million individual plants per year. This study investigated the morphological variation of the plant at the population and species levels to assist plant breeders working on domestication and government agencies responsible for conservation of the species. Examination of leaves and flowers suggest morphological of the species is relatively low, but that several populations have unique morphological characteristics.
Lyle E. Craker, Zoë Gardner, and Selma C. Etter
Ekaterina A. Jeliazkova, Valtcho D. Jeliazkov, Lyle E. Craker, and Baoshan Xing
Phytoremediation has been suggested as a solution to heavy metal—polluted soils, but the choices of suitable plant species for phytoremediation have been limited. Medicinal and aromatic plants appear to be excellent selections for these plantings, since these plants are grown for economically valuable secondary products (essential oils), not for food or feed. Preliminary research indicates that heavy metals are not accumulated in essential oils, permitting the oil to be used commercially. Productivity of some, but not all aromatic plants was reduced, however, by the heavy metals. The objective of our experiment was to distinguish the mechanism of heavy metal tolerance of plants using germinating seeds of medicinal and aromatic plant species. Seeds from medicinal and aromatic plants were germinated in solutions with selected levels of heavy metals (cadmium at 6 and 10 (μg·L-1; copper at 60 and 150 μg·L-1; lead at 100 and 500 μg·L-1; zinc at 400 and 800 μg·L-1) and in distilled water. Tests on Anethum graveolens L., Carum carvi L., Cuminum cyminum L., Foeniculum vulgare Mill., Pimpinella anisum L., Ocimum basilicum L., and the hyperaccumulator species Brassica juncea L. and Alyssum bertolonii established that different plant species reacted in different ways to the heavy metals. For example, cadmium did not decrease seed germination of Alyssum, O. basilicum, and B. juncea compared with germination in water but did decrease germination of C. cyminum. Lead did not affect germination of A. bertolonii and B. juncea as compared with water but did negatively affect germination of P. anisum, F. vulgare, and C. cyminum. Except for B. juncea, F. vulgare, and C. cyminum, copper had a negative effect on germination. Zinc decreased germination in all tested species except B. juncea.
Hussein Al-Amier, Khaled A. Nasr, Lorna Lück, and Lyle E. Craker
Black cohosh [Actaea racemosa L.; syn. Cimicifuga racemosa (L.) Nutt.] is a medicinal plant native to America and the woodlands of eastern North America. The roots and rhizomes of black cohosh, used by Native Americans to ease childbirth and treat menstrual cramps, rheumatism, headaches, coughs, asthma, and snakebites, are currently popular as an herbal remedy in the United States and Europe for the relief of discomfort associated with menopause. To determine chemical variation among populations of this perennial plant, root samples from 33 locations within the natural range of the species, ranging from Massachusetts to South Carolina and west to Missouri and Tennessee, were collected and chemically analyzed by HPLC-PDA using a C-18 reversed phase column (Phenomenex) for separation of the chemical constituents. The constituents were identified by comparison with commercial standards, including actein, methyl-beta-arabinopyranoside, caffeic acid, cimicifugoside, cimicifugoside H1, cimiracemoside A, 26 deoxyactein, ferulic acid, isoferulic acid, kaempferol, formononetin, and others. Chemically, an extract of the root and rhizome is known to contain at least three major natural product groups: cycloartenal-type triterpenes, phenolics, and flavonoids. Chemical constituents, especially formononetin, varied among the populations.