The contribution of aerial plant parts versus the root zone to the removal of volatile formaldehyde by potted Fatsia japonica Decne. & Planch. and Ficus benjamina L. plants was assessed during the day and night. The removal capacity of the entire plant, aerial plant parts, and root zone was determined by exposing the relevant parts to gaseous formaldehyde (2 μL·L ⁻¹ ) in airtight chambers (1.0 m ³ ) constructed of inert materials. The rate of formaldehyde removal was initially rapid but decreased as the internal concentration diminished in the chamber. To compare the removal efficiency between species and plant parts, the time interval required to reach 50% of the initial concentration was determined (96 and 123 min for entire plants of F. japonica and F. benjamina , respectively). In both species, the aerial plant parts reduced the formaldehyde concentration during the day but removed little during the night. However, the root zone eliminated a substantial amount of formaldehyde during the day and night. The ratio of formaldehyde removal by aerial plant parts versus the root zone was similar for both species, at ≈1:1 during the day and 1:11 at night. The effectiveness of the root zone in formaldehyde removal was due primarily to microorganisms and roots (≈90%); only about 10% was due to adsorption by the growing medium. The results indicate that the root zone is a major contributor to the removal of formaldehyde. A better understanding of formaldehyde metabolism by root zone microflora should facilitate maximizing the phytoremediation efficiency of indoor plants.

Foliage plants of Hedera helix L. (english ivy), Spathiphyllum wallisii Regal (peace lily), Syngonium podophyllum Schott. (nephthytis), and Cissus rhombifolia Vahl. (grape ivy) were evaluated for their ability to remove two indoor volatile organic air pollutants, benzene and toluene. Removal was monitored when the aerial portion of plants was exposed singly to 1 μL·L ^-1 or to 0.5 μL·L ^-1 of each gas in a closed environment over 6-hour periods during the day and the night. Selected physiological processes were assessed before and immediately after treatment to determine the effect of the gases on the plants. The effectiveness of plants in the removal of air pollutant(s) varied with species, time of day, and whether the gases were present singly or as a mixture. When exposed to a single gas, S. wallisii, S. podophyllum, and H. helix displayed higher removal efficiencies (ng·m ^-3 ·h ^-1 ·cm ^-2 leaf area) of either gas than C. rhombifolia during the day. The efficiency of removal changed when both gases were present; H. helix was substantially more effective in the removal of either benzene or toluene than the other species, with the removal of toluene more than double that of benzene. When exposed singly, the removal of both compounds was generally higher during the day than during the night for all species; however, when present simultaneously, H. helix removal efficiency during the night was similar to the day indicating that stomatal diffusion for english ivy was not a major factor. The results indicated an interaction between gases in uptake by the plant, the presence of different avenues for uptake, and the response of a single gas was not necessarily indicative of the response when other gases are present. Changes in the rates of photosynthesis, stomatal conductance, and transpiration before and after exposure indicated that the volatiles adversely affected the plants and the effects were not consistent across species and gases. Deleterious effects of volatile pollutants on indoor plants may be critical in their efficacy in improving indoor air quality and warrant further study.

The objective of this study was to compare physiological and psychological relaxation by assessing heart rate variability (HRV), prefrontal cortex activity, and subjective indexes while subjects performed a task with and without foliage plants. In a crossover experimental design, 24 university students performed a task transferring pots with and without a foliage plant for 3 min. HRV and oxyhemoglobin (oxy-Hb) concentration in the prefrontal cortex were continuously measured. Immediately thereafter, subjective evaluation of emotions was performed using a modified semantic differential (SD) method and a profile of mood state questionnaire (POMS). Results showed that the natural logarithmic (ln) ratio of low frequency/high frequency, as an estimate of sympathetic nerve activity, was significantly lower while performing the task with foliage plants for the average 3 min measurement interval. Oxy-Hb concentration in the left prefrontal cortex showed a tendency to decrease in the 2–3 min interval in the task with foliage plants compared to the task without plants. Moreover, significant psychological relaxation according to POMS score and SD was demonstrated when the task involved foliage plants. In conclusion, the task involving foliage plants led to more physiological and psychological relaxation compared with the task without foliage plants.

The objective of this study was to determine the exercise intensities of 10 gardening tasks for men and women in their 20s. Fifteen university students [(mean ± SD) age 24.7 ± 1.4 years and body mass index 23.5 ± 4.1 kg·m ⁻² ] participated in this study. On two occasions, the subjects completed 10 gardening tasks in a high tunnel and a grassy area with weeds located near the high tunnel in Cheongju, Chungbuk, South Korea. They performed five gardening tasks randomly ordered on each occasion. Subjects did each gardening task for 5 minutes and then sat and rested in a chair for 5 minutes before the next task. Each subject wore a portable telemetric calorimeter and respired into the facemask during the gardening tasks and resting periods to measure their oxygen uptake. The subjects also wore a heart rate monitor under their breast to record heart rate data during the gardening tasks and resting periods via radiotelemetry. The 10 gardening tasks performed by the subjects were determined to be moderate- to high-intensity physical activities [3.5 ± 0.5 to 6.3 ± 1.2 metabolic equivalents (MET)]. In conclusion, the exercise intensity of gardening tasks should be useful information for developing garden exercise programs that meet the recommended physical activity for health benefits in adults.

This study was conducted to determine the effects of a horticultural therapy (HT) program, based on B.F. Skinner’s behavior modification theory and special education science curriculum for Korean children with intellectual disabilities for the improvement of attention and sociality. Twenty-four participants (10 males, 14 females, in grades 1 to 3) with intellectual disabilities were recruited from a special education class at an elementary school in Seoul, South Korea. Twelve children participated in the HT program after-school for 6 months (Mar. to Aug. 2009, once per week, ≈40 min per session); the control group consisted of the remaining 12 children. Before and after the HT program, Conners’ teacher rating scales—revised and the social skills rating system assessments were conducted by parents/caregivers or teachers for each of the children. Analysis of covariance (ANCOVA) and chi square tests were used to compare differences between the two groups. Difference in attention was not significant between groups. Children in the HT group had statistically significant higher sociality scores than those in the control group ( P < 0.001). In conclusion, the HT program improved the sociality of children with intellectual disabilities. To maximize the therapeutic effects of the HT program for attention, the program should be revised and supplemented based on the results in this study. A larger sample size and factoring in the level of disability and year in school of the participants would increase the precision in assessing therapeutic effects.

This study used electromyographic analysis to investigate specific upper limb and hand muscle activation during 15 common horticultural activities. A total of 30 Korean adults between the ages of 20 and 30 years, with an average age of 24.8 years, were recruited from Konkuk University, Seoul, South Korea. Electromyographic measurements were made using a portable four-channel electromyograph. Bipolar surface electromyography (EMG) electrodes were attached to six upper limb muscles (i.e., upper trapezius, triceps—long head, biceps brachialis, flexor carpi ulnaris, flexor carpi radialis, and brachioradialis) and two hand muscles (i.e., thenar eminence and hypothenar eminence) on the dominant hand. These eight muscles that were selected play a major role in the operation of upper limbs and hand muscles for upper body low-impact activities. Each participant did the 15 horticultural activities on one occasion with two separate sessions. Each activity was performed for 60 seconds followed by a 15-second rest period sitting at a table on a height-adjusted chair between each activity. All eight muscles measured were used together during most of 15 horticultural activities. Upper trapezius, thenar eminence, and hypothenar eminence had higher muscle activity than the other muscles. Triceps—long head displayed very low EMG values compared with the other muscles. The EMG data will facilitate developing scientific and research-based gardening intervention and/or horticultural therapy programs for improving physical health and physical rehabilitation.