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Ki-Cheol Son and Y. Chae

The interaction between polyamines and ethylene is still not clear for floral tissues. The aim of the present paper is to examine the senescence on the isolated petals of carnation (Dianthus caryophyllus cv. Desio) but not the whole flower in an attempt to clarify the exact role of polyamines. Petals were treated with putrescine (Put; 0.0, 1.0, 10mM), spermidine (Spd; 0.0, 1.0, 10mM), spermine (Spn; 0.0, 1.0, 10mM), Put+Spd (1.0mM), Put+Spn (1.0mM). The fresh weight of petals in all 10mM treatment was decreased less than those in the other treatments at all times but there were no significant differences. The differences in ethylene production were significant. In petals maintained in 10mM of polyamines, ethylene production was completely inhibited until 13 days and senescence was considerably retarded. However, ethylene productions in 1.0mM polyamines treatments were delayed 2-3 days with reduced amounts. These results suggest that high concentrations of polyamines retard senescence and completely inhibit ethylene production. ACC content, activities of ACC synthase and SAM decarboxylase were analyzed. Finally, the role of SAM in ethylene and polyamines biosynthesis will be discussed.

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Ki-Cheol Son, Y. Chae, and Y. Lee

During the aging of H. syriacus flower, biosynthetic pathways of ethylene and polyamines, their interactions, and their effects on senescence were investigated. The evolution of ethylene in ephemeral flower was rapidly increased immediately after initiation of in-rolling of corolla at which EFE activity became maximum peak. After that, EFE activity was gradually decreased even though the aging was continued. Ethylene production was, however, slightly inhibited by the treatments of AOA and putrescine. The activity of ACC synthase and SAM decarboxylase were most rapidly increased at the time of 36th hrs. The contents of ACC and MACC were gradually increased from the early stage. However, ACC contents was decreased at the final stage but MACC was continuously increased. In normal condition, endogenous level of polyamines exists in the order of putrescine>spermidine>spermine. Putrescine was reduced from the initial point of aging, but spermidine and spermine were reduced from the middle and final stage of aging, respectively.

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Allan M. Armitage and Ki-Cheol Son

Plants of blue spirea (Caryopteris incana Mig.) were evaluated as cut flowers in the field and greenhouse. When subjected to several photoperiods but similar cumulative quanta, plants flowered more rapidly at 8 hours than at 12 hours and did not reach the macrobud stage at 16 hours. Stems were longer and their count was significantly higher with a 16-hour than an 8-hour photoperiod. In the field, yield and stem diameter were similar in full sun and in 55% shade. Stem length, however, significantly increased under shade.

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Ki-Cheol Son, Ray F. Severson, and Stanley J. Kays

Methodology was developed for the rapid quantitative and qualitative screening of sweetpotato [Ipomoea batatas (L.) Lam.] germplasm for the concentration of the major sweetpotato weevil oviposition stimulant, boehmeryl acetate, and its alcohol, boehmerol. The major surface components were rapidly quantified, using a minimum of plant material. Boehmeryl acetate, present in methylene chloride root extracts, did not degrade when held under normal laboratory conditions for 45 days. Boehmeryl acetate and boehmerol were found only in the outer 1 to 1.2 mm of periderm and the distribution of the compounds appeared to be relatively uniform over the surface of the root.

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Ki-Cheol Son, Ray F. Severson, and Stanley J. Kays

Levels of major root surface components for two sweetpotato [Ipomoea batatas (L.) Lam.] cultivars that differ in susceptibility to the sweetpotato weevil [Cylas formicarius elegantulus (Summers)] were determined. Analyses were made 30 days before harvest, at harvest, after curing, and after 2 months of storage during two seasons. Significant variation in the amounts of individual components, especially boehmeryl acetate, which is known to be an ovipositional stimulant for the weevil, was found before and after harvest, with season, and between cultivars. These results suggest that variation in field susceptibility of cultivars displaying moderate levels of resistance may be due in part to seasonal variation in the level of ovipositional stimulants.

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Dong Sik Yang, Ki-Cheol Son, and Stanley J. Kays

A broad cross-section of volatiles emanating from four species of popular indoor ornamental plants (Spathiphyllum wallisii Regel, Sansevieria trifasciata Prain, Ficus benjamina L., and Chrysalidocarpus lutescens Wendl.) was identified and categorized based on source. Volatile organic compounds from individual plants were obtained using a dynamic headspace system and trapped on Tenax TA during the day and again at night. Using short-path thermal desorption and cryofocusing, the volatiles were transferred onto a capillary column and analyzed using gas chromatography–mass spectroscopy. The volatiles originated from the plants, media/micro-organisms, pot, and pesticides. A total of 23, 12, 13, and 16 compounds were identified from S. wallisii, S. trifasciata, F. benjamina, and C. lutescens, respectively. The night emanation rate was substantially reduced (i.e., by 30.1%, 69.5%, 73.7%, and 63.1%, respectively) reflecting in part the regulation of biosynthesis and the greater diffusion resistance when the stomata were closed. S. wallisii had the highest emanation rate, releasing 15 terpenoid compounds [e.g., linaloloxide, linalool, (Z)-β-farnesene, farnesal, (+)-δ-cadinene, (+)-β-costol] into the surrounding air. Alpha-farnesene (90.3%) was quantitatively the dominant volatile present followed by (Z)-β-farnesene (1.4%), (+)-β-costol (1.4%), and farnesal (1.1%). Substantially fewer terpenoids (i.e., two, nine, and eight) emanated from S. trifasciata, F. benjamina, and C. lutescens, which quantitatively emitted fewer volatiles than S. wallisii. Most terpenoids from the four species were sesquiterpenes rather than monoterpenes. Methyl salicylate, a plant-signaling compound, was emitted by all four species. Certain volatiles (e.g., 2-chlorobenzonitrile, 1-ethyl-3,5-dimethylbenzene) were released from growth media and/or micro-organisms therein; other sources included the plastic pot (e.g., 2-ethyl-1-hexanol, octamethyl cyclotetrasiloxane) and pesticide ingredients [e.g., 2-(2-methoxy- ethoxy)ethanol, 2-ethylhexyl salicylate, homosalate].

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Sin-Ae Park, Kwan-Suk Lee, and Ki-Cheol Son

The objective of this study was to determine the exercise intensities of 15 gardening tasks in older adults using a portable indirect calorimeter. Twenty older Korean adults (16 females, four males) older than 65 years of age (average 67.3 ± 2.7 years) were recruited from the community of Gwangjin-gu, Seoul, South Korea. The subjects visited a garden created for the study at Konkuk University, Seoul, South Korea, three times and performed a total 15 gardening tasks. Subjects wore a portable calorimetric monitoring system (Cosmed K4b2) with telemetry that allowed measurement of oxygen consumption as they conducted each gardening task over a 5-min period and during a subsequent 5-min rest period while seated on a chair between each task. Their heart rate was also continuously measured using radiotelemetry (Polar T 31) during the test. The gardening tasks performed were of low to moderate intensity physical activities [1.7–4.5 metabolic equivalents (METs)]. Tasks using both upper and lower body (e.g., digging, fertilizing, weeding, raking, tying plants to stakes) required moderate-intensity physical activity (3–4.5 METs); those using the upper body while standing or squatting (e.g., pruning, mixing soil, planting seedlings, sowing, watering using a watering can or hose, harvesting) were low-intensity physical activities (1.7–2.9 METs); and tasks requiring limited use of the upper body while standing (e.g., filling containers with soil, washing harvested produce) were the least demanding physical activities of the gardening tasks tested. The results will allow more precise tailoring of gardening activities of older individuals to achieve appropriate levels of activity for good health.

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Seong-Sil Kim, Sin-Ae Park, and Ki-Cheol Son

For older elementary school students, amicable peer relationships are important to meeting developmental challenges, such as socialization. Thus, in this study, the effectiveness of a school gardening program to promote positive social relationships among elementary school students was assessed. The participants in this study were fifth and sixth grade students from four elementary schools in Wonju, South Korea. The experimental and control groups consisted of 123 students each (total 246) from fifth and sixth grade classrooms. The gardening program included a range of activities, such as sowing seeds and harvesting produce, and was designed to improve peer status, peer relations, and sociality. The program was embedded in the school curriculum; sessions were 90 minutes per week for 10 weeks from 16 April through 25 June 2012. The results revealed the school gardening program brought about meaningful differences in both persistence of friendship (P = 0.04) and adaptability between friends (P = 0.03), which were subcategories of peer relationships, in the experimental group. There were also significant improvements in sociality (P < 0.001) and its various subcategories, especially in law-abiding (P < 0.001) and collaboration (P < 0.001). Finally, the peer status results showed that there was significantly a greater increase in the peer status after the school gardening program, but there was no significant change in the control group. In conclusion, the school gardening program for elementary school students had a positive influence on peer relationships, sociality, and peer status. Implementing a garden program in schools will effectively contribute to the improvement of social relationships among elementary school students.

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Ki-Cheol Son, Ray F. Severson, Maurice E. Snook, and Stanley J. Kays

Methanol extracts of external (outer 3 mm) and interior root tissue of four sweetpotato [Ipomoea batatas (L.) Lam.] cultivars (`Centennial', `Jewel', `Regal', and `Resisto') having different levels of susceptibility to the sweetpotato weevil [Cylas formicarius elegantulus Summer] were analyzed for simple carbohydrates (fructose, glucose, sucrose, inositol) and organic acids (malic, citric, quinic) by gas chromatography and for phenolics (caffeic acid, caffeoylquinic acids, rutin) by high-performance liquid chromatography. There were significant differences among cultivars in the concentrations of total sugars and phenolics in the external tissue (P < 0.05). In addition, the distribution of carbohydrates, organic acids, and chlorogenic acid [3-O-caffeoylquinic acid] differed between external and interior tissues. Sucrose was the major water-soluble carbohydrate in all cultivars. With the exception of malic acid, the concentration of carbohydrates, organic acids, and phenolics did not correlate with cultivar susceptibility to the sweetpotato weevil.

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Sang Deok Lee, Soon Jae Kim, Seung Il Jung, Ki-Cheol Son, and Stanley J. Kays

CO2 assimilation rate of Crassula hybrid `Himaturi', a succulent ornamental species with the crassulacean acid metabolism (CAM) photosynthetic pathway, was affected by light intensity (50, 100, 300 μmol·m–2·s–1), photoperiod (16/8, 8/16 h day/night), and temperature (30/25, 25/20 °C day/night). Maximum assimilation of CO2 occurred at 300 μmol·m–2·s–1 of diurnal irradiance, 16/8 h day/night photoperiod, and a day/night temperature of 30/25 °C. Diurnal CO2 assimilation patterns of nine succulent ornamental CAM species were evaluated (300 μmol·m–2 s–1, 35/25 °C day/night and a 16/8-h day/night photoperiod) for CO2 fixation. Of the nine ornamentals, Crassula `Himaturi' had the highest and Echeveria derembergii the lowest maximum CO2 absorption rate (13.0 vs 2.4 μmol kg–1·s–1), total nighttime (179.3 vs 13.4 mmol·kg–1), and 24 h total (200.6 vs 19.0 mmol·kg–1) absorption. Based on the CO2 assimilation patterns, the nine ornamentals were separated into two groups: 1) full CAM (Faucaria tigrina, Gasteria gracilis var. minima, Haworthia cymbiformis, and Haworthia fasciata); and 2) weakly CAM (Adromischus clarifolius, Crassula hybrids `Moonglow' and `Himaturi', E. derembergii, and Haworthia retusa).