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Jason McAfee and Curt Rom

Pesticides and alternative fruit thinners are needed for certified organic fruit growers. Transient reductions in photosynthesis (Pn) have proven an effective technique for fruit thinning. Pesticides can be detrimental to plant growth by Pn reduction. This study was developed to measure plant response to foliar applications of essential oils at 2% concentrations. Treatments were applied to vegetative apple trees grown under controlled environment conditions to study photosynthetic effects. There was no significant effect on Pn for treatments; however, clove oil was very phytotoxic and defoliated all trees in this study. Cinnamon oil and cedarwood oil significantly decreased evapotranspiration and stomotal conductance 1 day after treatment. Differences in plant growth were not significantly different for all treatments excluding clove oil. Studies on concentration effects may determine horticultural usefulness of these compounds.

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Ritika Gupta, S. Banerjee, G.R. Mallavarapu, S. Sharma, S.P.S. Khanuja, A.K. Shasany and Sushil Kumar

.co.in Grateful thanks are due to S. Ramesh, S.A. Hasan, and Shalini Rai for the GC analysis of oil and preparation of the manuscript, and to the Dept. of Biotechnology, Government of India, for partial financial support.

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M. Rawgappa, H.L. Bhardwaj, A.I. Mohamed, M.E. Showhda and M.E. Kraemer

Thirty-five mint accessions were evaluated during 1993 for agronomic characteristics (leaf texture, color, and pubescence), plant vigor, cold hardiness, insect population interactions, and contents of essential oils, ash, and total protein. These accessions were obtained from National Clonal Germplasm Repository, Corvallis, Oregon during 1992. The rhizomes were planted in the greenhouse on April 2, 1992 and transplanted to the field on May 29, 1992 as a randomized complete block design with three replications. The chemical composition data from whole plants indicated that ash content was dependent upon location from which an accession was collected, ploidy level (diploid vs. polyploid), type of mint (peppermint vs. spearmint), and genetics (hybrid vs. non-hybrid). Diploid accessions had significantly higher essential oil content. The protein content was higher in peppermint types than spearmint types. The hybrid accessions had lower protein content in comparison to non-hybrids.

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Renee G. Murray and James E. Simon

Essential oil content of Ocimum basilicum, cv. sweet basil, increases with plant maturity. The increase in essential oil content may correspond to the formation of glandular trichomes during leaf expansion. Greenhouse grown plants were harvested every 2 weeks. Leaves were grouped according to size, examined with a stereo microscope, and trichome densities compared. Results indicate that trichome formation continues throughout leaf expansion. In young basil plants, leaves ranged in size from 2-30cm2 Highest density (416 trichomes/cm2) occurred in leaves 2–6c m2. Prior to open bloom, leaves ranged in size from 2-49cm2. Highest density occurred in leaves 18-24c m2. In flowering plants leaves ranged in size from 2-34cm2, yet there was NSD in trichome density in leaves of different sizes. Analysis of the entire leaf surface of plants at each harvest showed the greatest density of trichomes in plants at full bloom (280 trichomes/c m2). All leaves have visible glandular trichomes. These glandular trichomes are most likely formed both prior to and during leaf expansion.

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Mario R. Morales and James E. Simon

`African Beauty', a new ornamental camphor basil cultivar, was developed through three cycles of selfing and selection from USDA accession PI 500942, originally collected in Zambia, Africa. `African Beauty' was field-evaluated and compared with PI 500942 (the original population), PI 500954 (another accession from Zambia), a camphor cultivar from Companion Plants, and three other related lines in 1997 and 1998. Most commercial camphor basils are tall (50 to 60 cm), late-flowering, and unattractive. Our goal was to develop a new cultivar that had a short stature (≈40 cm), an early flowering, and an attractive appearance. The outcome was `African Beauty', which has the following characteristics: plant height: 30 to 35 cm, plant spread: 50 to 55 cm, leaf length: 6.3 to 6.7 cm, days to flower: 76 days, inflorescence length: 25 cm, essential oil yield: 3 mL/100 g dw. The essential oil of `African Beauty' is also highly aromatic, with 72% camphor, 12% camphene, and 9% limonene. The plant is a fast-growing, semicompact aromatic plant that produces small leaves and large quantities of long and slender inflorescences that, when fully developed, curve at the tip like the tail of a cat. Blooming usually lasts from 20 to 25 days, when the plant looks most beautiful. `African Beauty' is an attractive ornamental that would be excellent as a garden border plant, or as an indoor potted plant.

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Roberto F. Vieira and James E. Simon

To determine the mode of inheritance of citral, linalool, methylchavicol, and methylcinnamate in basil, controlled crosses were made between chemotypes rich in each of these constituents. Four stable Ocimum basilicum populations selected for high methylcinnamate (79%), methylchavicol (95%), linalool (82%), and citral (65%) respectively, served as parents. Crosses were made using chemotypes rich in terpenes (linalool × citral), in phenylpropanoids (methylchavicol × methylcinnamate), and a third that combines chemotypes from both biosynthetic pathways (linalool × methylchavicol). True hybrids were selfed in isolation and one hundred F2 plants were analyzed for their oil composition. The parents, the F1 hybrids and the F2 generation of all plants were evaluated in a field trial under identical environmental conditions. Plants were harvested at full flowering, and dried at 380 °C. Identification of essential oil constituents were confirmed by GC/MS. The F2 segregation data for each major oil constituent trait will be examined by c2 analysis tests. Preliminary results indicate that methylcinnamate segregates in a 3:1 ratio, and is a dominant major gene. In the two crosses using methylcinnamate chemotype as a female parent, the F2 population segregates in 80:22 and 65:28 methylcinnamate:non-methylcinnamate plant types, with P = 0.42 and 0.25 and c2=0.64 and 1.29, respectively. Analysis of the other crosses are being processed, evaluating qualitative and quantitatively the presence or absence of each constituent in their F2 population.

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C.L. Murphy, N.W. Hopper, C.B. McKenney and D.L. Auld

The oil extracted from seed of selected accessions of Oenothera, also known as the wildflower evening primrose, has documented medical applications. Evening primrose oil contains from 0.0 to 12.0% gamma-linolenic acid (GLA) (C 18:3, delta 6, 9, 12). This unique fatty acid, which occurs in only a few plant species, can correct deficiencies in the delta 6 desaturase enzyme. Low levels of this enzyme prevent formation of the long chain fatty acids responsible for the production of prostaglandins and thromboxanes. Supplementation of the diet with evening primrose oil rich in GLA ensures adequate levels of these essential products. Inconsistent seed germination, poor emergence, and small seed size of accessions containing higher levels of GLA have limited commercial production of this crop. Currently, most producers establish their field through transplants. In this project, methods of improving seed germination have been explored. Seed coatings using diatomaceous earth were shown to facilitate handling and improve germination in the laboratory. Osmotic priming and red light exposure were also evaluated as means of improving germination.

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Susan L.F. Meyer, Dilip K. Lakshman, Inga A. Zasada, Bryan T. Vinyard and David J. Chitwood

from the environment, and often have low toxicity to mammals ( Bainard et al., 2006 ). An essential oil that has been investigated for use as a pesticide against multiple pathogens and pests is derived from the clove plant. Clove oil has demonstrated

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Linda M. Falzari, Robert C. Menary and Valerie A. Dragar

1 To whom reprint requests should be addressed; e-mail Linda.Falzari@utas.edu.au . We gratefully acknowledge the Horticultural Research and Development Corporation, Essential Oils of Tasmania Pty Ltd and Natural

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Susan Kreder and Albert H. Markhart III

Environmental conditions are known to affect the growth and quality of culinary and medicinal herbs. Hydroponic growing conditions often produces greater yields for many leafy crops compared to growth in more-traditional media. The objective of this investigation was to compare the yield and quality of sweet basil grown in continuous flow solution culture or well-irrigated Universal Mix. Sweet basil plants were germinated under mist and then transplanted to a continous-flow hydroponics system or to 6-inch pots containing Universal Mix. Rows of pots alternated with a row of hydroponic plants in a temperature-controlled greenhouse. Temperatures were maintained between 20 and 25 °C, the relative humidity was not controlled, pot-grown plants were irrigated as needed. HID lights added sublimentry irradiation and maintained a photoperiod of 18 h. Cohorts of plants were harvested at five time points between transplanting and maturity. Plants were divided into leaves, stems, and roots, dried, and the data subjected to mathmatical growth analysis. Several leaves from each plant were harvested and analyzed by gas chromotograpth for essential oils. Plants grown in hyroponics grew faster and produced more harvestable leaf material than the media-grown plants. Details of the plant growth analysis and the essential oil composition will be presented.