The content of essential oil, thymol, and carvacrol in a thymol-type of clonally selected thyme plants during different developmental stages were investigated under greenhouse and field conditions. Plants in the greenhouse were grown from July to November, under natural light and natural light supplemented by a PPF of 200 μmol·m–2·s–1, provided by HPS lamps, while plants in the field were studied from June to November. Shoot yield and the accumulation of the active principles from greenhouse-grown plants were determined by harvesting the plants at 40-, 60-, and 120-day intervals, while field-grown plants were harvested in August, September, October, and November. Essential oil content, qualitative and quantitative changes in the oil were determined by subjecting the samples to steam distillation and subsequent gas chromatographic analysis. There were important changes in shoot yield, essential oil, thymol, and carvacrol content in the course of plant development. After 120 days of growth under greenhouse conditions, the essential oil content increased by >150%, while thymol content increased by ≈200% compared with the 40-day-old plants. We found some differences in oil content, thymol, and carvacrol accumulation between field- and greenhouse-grown plants. The pattern of crop yield and the accumulation of the major active substances under field and greenhouse conditions are presented and discussed.
W. Letchamo, C. Mengle, and A. Gosselin
Lucette LaFlamme, Marie-Hélène Michaud, and Nicholas Tremblay
Cultivation of thyme for medicinal purposes should result in high dry-matter yield and sufficient active principals concentrations. In this experiment two methods of crop establishment were compared: direct sowing (final plant density: 100,000 plants/ha) and planting at two densities: D-1 (100,000 plants/ha) and D-2 (166,000 plants/ha). The use of transplants promoted growth and resulted in yields three times higher than direct sowing (3340 vs. 1002 kg dry matter/ha). There were significant differences in biomass between the two densities evaluated. Plants under D-1 weighed 33 g dry matter/plant vs. 22 g dry matter/plant for D-2. Hence, dry-matter yield per hectare was not affected by planting density. Active principals concentrations were not affected by treatments. So far, it is recommended that cultivation of thyme under Quebec's conditions be based on transplanting at moderate (100,000 plants/ha) density.
Annika E. Kohler and Roberto G. Lopez
. Litvin-Zabal (2019) reported shoot fresh and dry mass increased when increasing the DLI for hydroponically grown mint ( Mentha spp.), oregano ( Origanum vulgare ), sage ( Salvia officinalis ), and thyme ( Thymus vulgaris ). For example, the shoot fresh
Raymond A. Cloyd and Nina L. Cycholl
A greenhouse study was conducted from Oct. 1999 through Feb. 2000, and Mar. 2001 through Apr. 2001, to determine the potential phytotoxic effects of selected insecticides on Spanish lavender (Lavandula stoechas L.), oregano (Origanum vulgare L. `Santa Cruz'), rosemary (Rosmarinus officinalis L.), St. Johnswort (Hypericum perforatum L. `Topaz'), wolly thyme (Thymus vulgaris L. `Wolly'), and nutmeg thyme (Thymus vulgaris L. `Nutmeg'). Insecticides used for the study were Beauveria bassiana Strain GHA, pyrethrin [+ piperonyl butoxide (PBO)], azadirachtin, potassium salts of fatty acids, two rates of cinnamaldehyde, paraffinic oil, and capsaicin. Visual observations of phytotoxicity were made 7 days after the final application. Pyrethrin, potassium salts of fatty acids, and both rates of cinnamaldehyde were consistently more phytotoxic than the other insecticides. Despite the phytotoxic effects from some of the insecticides, new growth that emerged following treatments compensated for the initial damage, and the herbs were still saleable.
Nicolas Tremblay, Marie-Hélène Michaud, René Crête, and André Gosselin
With the increase in popularity of natural medicine there is an ever growing market for the production of medicinal plants. In the last decade, screening trials of a number of species were conducted. The species currently under study are: angelica (Angelica archangelica; biennial, roots harvested), thyme (Thymus vulgaris; perennial, shoot harvested), German chamomilla (Matricaria recutita; annual, flowers harvested), horehound (Marrubium vulgare; perennial, shoot harvested) and dandelion (Taraxacum officinale; considered as a biennial, roots harvested). In 1990 the species were grown on three soil types (clay-loam, sandy loam and histosol) with different fertilization and irrigation practices. In 1991 two distinct trials were undertaken. The first considered herbicide efficiency and planting density. The second dealt with «organic» management strategies. Depending on the species, treatments of compost amendment, plastic mulch and implantation techniques were compared.
Manuel C. Palada and Stafford M.A. Crossm
The Caribbean region is one major source of most herbs and spices consumed in the U.S. Although the U.S. Virgin Islands (USVI) is part of the Caribbean, local production of herbs and spices does not contribute significantly to exports into the U.S. market. Nevertheless, culinary herbs area” important horticultural crop in the USVI and their sale provides income for many small-scale growers. Little research has been done to improve field production in the USVI. Inefficient cultural practices used by growers result in low yields. Lack of information on fertilizer rates, irrigation and pest control methods is a major constraint to high yields. In 1988, the Agricultural Experiment Station initiated a project to improve field production of herbs and spices in the USVI. Use of drip irrigation, mulching and fertilizers has improved yields of basil (Ocimum basilicum) and thyme (Thymus vulgaris). This paper will discuss crop management studies to improve culinary herb production in the USVI. Increasing production may help reduce U.S. imports of these specialty crops from other Caribbean island nations.
Brent Tisserat and Robert Silman
An inexpensive ultrasonic fogging system is presented that aids in the establishment of tissue culture shoots in soil under greenhouse conditions. In addition, ultrasonic fogging may be coupled to CO2 nutrient enhancement via bubbling CO2 into the water reservoirs prior to fogging to improve growth and morphogenesis responses of shoots. A list and cost of items for the system and its assembly is given. Transplanted tissue culture shoots of basil (Ocimum basilicum L.), hosta (Hosta sp.), mint (Mentha sp.), and thyme (Thymus vulgaris L.) were tested with this fogging system with and without CO2 nutrient elevation and compared to the growth of shoots grown under a misting system with and without CO2 nutrient elevation. In all cases, ultrasonic fogging enhanced survival rates, growth (fresh weights) and morphogenesis (axially shoots, leaves and roots) vs. that occurring in the misting system. For example, thyme and mint shoots exhibited 2- and 5-fold increases, respectively, in fresh weights under ultrasonic fogging with CO2 compared to misting systems with CO2. Associated with enhanced survival and morphogenesis was an overall enhancement of shoot and leaf size and overall maturation responses. This is also reflected in enhanced secondary products obtained from shoots grown under ultrasonic fogging compared to shoots grown in misting systems.
Alexander A. Csizinszky
Sweet marjoram [(marjoram) Origanum majoranna], Italian parsley [(parsley) Petroselinum crispum], Summer savory [(savory) Satureja hortensis], and thyme (Thymus vulgaris) were evaluated for their yield potential during Fall–Winter–Spring (Oct.–May) 1998–99. The herbs were grown in a light sandy soil with the full-bed polyethylene mulch-micro(trickle) irrigation system. Experimental design was a split-plot replicated three times. Main plots were two N–P–K treatments: 0 N–P–K or N and K from a liquid 4–0–3.32 (N–P–K) fertilizer injected at 0.77 N and 0.64 K kg·ha–1·day–1. Sub-plots were four compost rates at 0x, 1x, 2x, and 4x (1x = 4.5 t·ha–1). Early and seasonal total yields of marjoram and savory were similar with injected N + K and 0x compost to yields with compost and with or without injected N + K fertilizer. Yields of parsley and thyme increased with increasing compost rates and were best with compost plus liquid N + K. Postharvest soil concentrations of NO3-N were lower in the parsley, than in the marjoram, savory and thyme plots. Residual concentrations of all other elements were similar with or without injected N + K or compost treatments.
Jerry T. Walker
Twenty herb species were exposed to root-knot nematode under greenhouse conditions. The root systems were examined for root gall development and nematode reproduction as an indication of host suitability. The herbs evaluated were balm (Melissa officinalis L.), basil (Ocimum basilicum L.), catnip (Nepeta cataria L.), chamomile (Matricaria recutita L.), coriander (Coriandrum sativium L.), dill (Anethum graveolens L.), fennel (Foeniculum vulgare Mill.), hyssop (Hyssopus officinalis L.), lavender (Lavandula augustifolia Mill.), oregano (Origanum vulgare L.), peppermint (Mentha ×piperita L.), rocket-salad (Erurca vesicaria L.), rosemary (Rosmarinus officinalis L.), rue (Ruta graveolens L.), sage (Salvia officinalis L.), savory (Satureja hortensis L.), sweet marjoram (Origanum majorana L.), tansy (Tanacetum vulgare L.), thyme (Thymus vulgaris L.), and wormwood (Artemisia absinthium L.). Peppermint, oregano, and marjoram consistently were free of root galls after exposure to initial nematode populations of two or 15 eggs/cm3 of soil medium and were considered resistant. All other herb species developed root galls with accompanying egg masses, classifying them as susceptible or hypersusceptible to root-knot nematode. The highest initial nematode egg density (15 eggs/cm3) significantly decreased dry weights of 14 species. The dry weights of other species were unaffected at these infestation densities after 32- to 42-day exposure.
Brent Tisserat and Steven Vaughn
The influence of a wide range of CO2 levels on the growth, morphogenesis, and secondary metabolite production in vitro was evaluated. Shoots of thyme (Thymus vulgaris L.) and a spearmint–peppermint cross (Mentha spicata × Mentha piperita) were grown on MS medium with and without 3% sucrose under 350, 1500, 3000, 10,000, and 30,000 μL CO2/L for 8 weeks. Dichloromethane extracts from leafs were analyzed using GC-MS techniques. Prominent peaks were identified by comparison with known standards. Highest growth (i.e., fresh weight) and morphogenesis responses (i.e., leafs, shoots and roots) were obtained when shoots were grown under 10,000 μL CO2/L regardless of whether or not sucrose was included in the medium. Ultra-high CO2 concentrations (3000 μL CO2/L) stimulated secondary metabolite production regardless of whether or not the medium contained sucrose. However, the combination of certain ultra-high CO2 levels (e.g., 3000 to 10,000 μL CO2/L) and the presence of sucrose in the medium resulted in shoots producing the highest levels of secondary metabolites. These results suggest that in vitro photosynthesis, which is stimulated by ultrahigh CO2 levels, may enhance secondary metabolite production.