Performing Department
Stockbridge School of Agriculture
Non Technical Summary
The herbal and botanical product market, estimated at more than US $60 billion in 2003, has been increasing at 6 to 8 % per year. According to the United Nations Comtrade Statistics, the estimated size of the global market for essential oils, fragrances, and flavors in 2013, was US $26 billion, growing an average rate of 8.1% in the past five years. The market for herbal dietary supplements in the United States has reached an estimated total of $6.4 billion, increasing by 6.85% in 2014 as compared with the previous year. Improvements in production of medicinal and aromatic plant products are needed to meet increased market demands.Early studies have demonstrated that soil microorganisms associated with plant roots can improve plant growth and development through various mechanisms, including increasing available nutrients to plants, synthesizing phytohormones, inducing plant stress tolerance, and suppressing pathogens. Although the mechanisms are not fully understood, studies have demonstrated that the use of soil microorganisms (PGPRs) can promote synthesis of secondary metabolites in plants, improving the quality and value of the medicinal and aromatic plants. While commercial PGPRs and mycorrhizal fungi are available for various grain crops and vegetables in the United States, few of these products are available for medicinal and aromatic plants. In the proposed study, PGPRs and mycorrhizal fungi will be studied for the growth and secondary metabolite synthesis in the Lamiaceae and other herbal families for their use in culinary and essential oil products. The development of PGPRs and mycorrhizal treatment that improve medicinal and aromatic plant yields and secondary metabolite production can lead to increased profits for growers and industries using natural products.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
The overall objective of this research is to use beneficial bacteria and fungi to improve medicinal and aromatic plant yields quantitatively and qualitatively. Specific objectives are:To determine if treatments with microorganisms can improve seed germination rate and seedling development of medicinal and aromatic plants.To determine if treatments with microorganisms can promote plant growth, increase antioxidant molecules, improve essential oil yield, and alter oil compositions in medicinal and aromatic plants.To determine whether the beneficial effects of microorganisms on growth and essential oil yields are observed under field conditions.
Project Methods
Seed germination and seedling developmentBasil and sage plants will be used for the following experiments as these plants are important for both culinary and essential oil usage. In addition, seeds of these plants germinate and develop seedlings relatively rapidly. Seeds will be purchased from Richters Herbs (357 Highway 47 Goodwood, ON L0C 1A0 Canada), a local seed company that supplies seeds to many farmers in New England area. Seeds will be surface sterilized using hydrogen peroxide that have been used successfully for sterilizing seeds in our laboratory. Surface sterilized seeds of basil and sage will be inoculated with eight microorganism treatments using MgSO4 solution to maintain osmotic balance within microorganisms as described by van Peer et al., (1990). Inoculated seeds will be germinated in Petri dish on agar containing half strength Hoagland solution under various environmental conditions including salt, temperature and pH. Seeds (30 - 40) will be sown in each Petri dish and three replicated Petri dish experiment will be tested for each condition. Germination rate, root length, hypocotyl length, and fresh and dry weight will be measured after seven days. Seedling vigor index (VI) will be calculated using the formula: VI = (mean root length + mean hypocotyl length) x germination percentagePlant growth and secondary metabolite productionPlants will be cultivated with and without microorganism treatments under greenhouse conditions to monitor secondary metabolite production. Seeds will be surface sterilized and be put in microorganism cultures and inoculated at room temperature. Inoculated microorganism suspensions will also added to the pot media, before the seeds are sown. To determine if higher seedling vigor index correlates with the later stage plant growth and higher plant yields, plants will be inoculated with three microorganism treatments with the highest seedling vigor index and three treatments with the lowest seedling vigor index. Each condition will be tested with three replicated samples. Basil plants will be grown for three months before harvesting and sage plants will be grown for four months before harvesting adjusting the time required for the plants to reach full development.Plant height will be monitored biweekly to monitor the plant growth during the development stage. Chlorophyll levels will also be monitored biweekly as the chlorophyll levels can indicate plant health and efficiency of photosynthesis. Chlorophyll measurements will be done using SPAD 502 Plus Chlorophyll Meters that allows instant and non-invasive measurement. After harvesting, leaf area, fresh and dry weight will be measured to estimate yield improvements.Harvested plant materials will be analyzed for secondary metabolites. Total phenols, flavonoids, and prolines will be measured for these phytochemicals have anti-oxidant activity and have been shown to protect human cells from oxidative stresses. Essential oil compositions will also be measured because of their importance in many industries including food and perfumery industries. For measuring flavonoids and phenols, dried leaves will be powdered and extracted with methanol, a versatile solvent for measuring flavonoids, and phenols. Total flavonoids will be measured by aluminum chloride colorimetric method, measuring the color change as AlCl3 forms acid stable complexes with flavonoids. Total phenols will be assessed using Folin Ciocalteu assay, a method widely used for measuring phenolic compounds because of the simple procedure and reproducible result, while the accuracy is compromised as Folin Ciocalteu reagent also react with other oxidation substrates. Prolines will be measured using the method described by Bates et al (1973), a common method to measure prolines that requires only a small amount (approx. 0.05g) of plant material. Antioxidant activity will be measured by DPPH assay that has been routinely used in our laboratory.Essential oils will be collected by hydrodistillation and the collected oils will be dried over anhydrous sodium sulphate and used for GC and GC/MS analysis, adopted as a standard method in our laboratory.Differences generated by the studies in these experiments will be separated by analysis of variance. Although time and budget may not permit the measurement of every single dependent variable identified as an absolute minimum, the constituency and quantity of essential oils in the plant materials will be identified as variables dependent on the inoculum species. The collected data will be appropriately analyzable by several F-tests, done for every possible combination of the two plant species and the essential oil constituents to determine which, if any of the oil quantity and/or constituency are enriched or depleted as a response to the different inocula. When the level of a constituency is present at a very low concentration, a judgement will be made as to whether those constituents at merit statistically analytical attention.Similarly, each of the other dependent variables specified will be analyzed by F-tests. Independent variables have been limited enabling the use of one-way ANOVAs.Field TrialsField trials will be conducted in the UMass farm site following seeding recommendations for basil and sage, respectively, to test the applicability and consistency of the use of microorganisms selected in Experiment 1 and 2. Growth and secondary metabolites will be measured over two growing seasons. Data analysis will be conducted as described in Experiment 2.