With the wide use of greenhouses, the working hours have been increasing inside the greenhouse for workers. In the closed ventilated greenhouse, the internal environment has less affected to external weather during making a suitable temperature for crop growth. Greenhouse workers are exposed to organic dust including soil dust, pollen, pesticide residues, microorganisms during tillage process, soil grading, fertilizing, and harvesting operations. Therefore, the health status and working environment exposed to workers should be considered inside the greenhouse. It is necessary to secure basic data on particulate matter (PM) concentrations in order to set up dust reduction and health safety plans. To understand the PM concentration of working environment in greenhouse, the PM concnentrations were monitored in the cut-rose and Hallabong greenhouses in terms of PM size, working type, and working period. Compare to no-work (move) period, a significant increase in PM concentration was found during tillage operation in Hallabong greenhouse by 4.94 times on TSP (total suspended particle), 2.71 times on PM-10 (particle size of 10 μm or larger), and 1.53 times on PM-2.5, respectively. During pruning operation in cut-rose greenhouse, TSP concentration was 7.4 times higher and PM-10 concentration was 3.2 times higher than during no-work period. As a result of analysis of PM contribution ratio by particle sizes, it was shown that PM-10 constitute the largest percentage. There was a significant difference in the PM concentration between work and no-work periods, and the concentration of PM during work was significant higher (p < 0.001). It was found that workers were generally exposed to a high level of dust concentration from 2.5 μm to 35.15 μm during tillage operation.
This study was carried out to investigate the effect of side vent heights on temperature and relative humidity inside and outside the single-span plastic greenhouse (W: 7 m, L: 40 m H: 3.9 m) during natural ventilation. Four different heights (120, 100, 80, 60 cm) of the side vent were used as an experimental condition. Variations of temperature and relative humidity inside and outside the greenhouse and the differences between heights were compared by using one-way ANOVA. In the daytime, the difference in temperature between inside and outside the greenhouse was dropped from 14.0°C to 7.1°C as the side vent height increased. The temperature difference in the nighttime was less than 0.2°C regardless of the height. One-way ANOVA on the temperature difference between heights presented that the statistical significance was founded between all of the combinations of height in the daytime. The difference in relative humidity between inside and outside the greenhouse was grown from –13.8% to – 22.2% with a decrease in the side vent height. The humidity difference in the nighttime was less than 1% regardless of the height. One-way ANOVA on the humidity difference revealed that most of the side vent heights showed significance in the daytime but between 100 and 80 cm was not significant. It seemed because the external air became cooler during the experiment with a height of 80 cm. Conclusively, this study empirically demonstrated that the higher side vents resulted in the decrease of differences in temperature and relative humidity between inside and outside the greenhouse, and also the effect of side vent height was statistically significant. This study may be helpful for deciding the height of the side vent effective for controlling temperature and relative humidity in a single-span greenhouse during natural ventilation.
Non-destructive estimation of leaf area is a more efficient and convenient method than leaf excision. Thus, several models predicting leaf area have been developed for various horticultural crops. However, there are limited studies on estimating the leaf area of strawberry plants. In this study, we predicted the leaf areas via nonlinear regression analysis using the leaf lengths and widths of three-compound leaves in five domestic strawberry cultivars (‘Arihyang’, ‘Jukhyang’, ‘Keumsil’, ‘Maehyang’, and ‘Seollhyang’). The coefficient of determination (R2) between the actual and estimated leaf areas varied from 0.923 to 0.973. The R2 value varied for each cultivar; thus, leaf area estimation models must be developed for each cultivar. The leaf areas of the three cultivars ‘Jukhyang’, ‘Seolhyang’, and ‘Maehyang’ could be non-destructively predicted using the model developed in this study, as they had R2 values over 0.96. The cultivars ‘Arihyang’ and ‘Geumsil’ had slightly low R2 values, 0.938 and 0.923, respectively. The leaf area estimation model for each cultivar was coded in Python and is provided in this manuscript. The estimation models developed in this study could be used extensively in other strawberry-related studies.
Plants under the genus Orostachys have been known as medicinal plants. This study deems to determine the growth and leaf color of Orostachys japonica and O. boehmeri when subjected to various LED light sources. A total of seven LED light treatments were used, i.e. red (630 nm), green (520 nm), blue (450 nm), purple (650 and 450 nm), 3000 K white (455, 600 nm), 4100 K white (455, 590 nm), and 6500 K white (450, 545 nm) LEDs. Results showed that O. japonica plants showed favorable growth under 4100 K white LED, while O. boehmeri plants had a positive growth response under white light LEDs (3000, 4100, and 6500 K). In leaf color analysis, the use of green LED showed the greatest change in CIELAB L * and b * values which were relatively higher compared to other treatments indicating that leaves turned yellowish. Further statistical analysis using Pearson’s correlation also suggested that there is a small negative association between dry weight and b * values of O. japonica, and a negative moderate association between plant weights (fresh and dry weight) and leaf color (L * and b * ) and positive association between said plant weights and a * color values of O. boehmeri. Therefore, it is recommended to cultivate O. japonica under 4100 K white LED and O. boehmeri under 3000, 4100, 6500 K white LEDs.
The Saemangeum has a dry surface characteristic with a low moisture content ratio due to the saline and silt soil, so the vegetation cover is low compared to other areas. In areas with low vegetation cover, wind erosion has a high probability of scattering dust. If the vegetation cover is increased by cultivating crops that can withstand the Saemangeum reclaimed environment, scattering dust can be reduced by reducing the flow rate at the bottom. Thus, the purpose of this study is to analyze the effect of suppressing the generation of fine dust and scattering dust by cultivating winter forage crops on the Saemangeum reclaimed land. While growing 0.5 ha of barley and 0.5 ha of triticale in Saemangeum reclaimed land, the concentration of fine dust was monitored according to agricultural work and growth stage. Changes in the concentrations of PM-10, PM-2.5, and PM-1.0 were monitored on the leeward, the windward and centering on the crop field. As a result of monitoring, PM-1.0 had little effect on crop cultivation. the concentration of PM-10 and PM-2.5 increased according to tillage and harvesting, and tillage had a higher increasing the concentration of PM-10 and PM-2.5 than that of harvesting. According to the growth stage of crops, the effect of suppressing scattering dust was shown, and the effect of suppressing scattering dust was higher in the heading stage than in the seedling stage. So, it was found that there was an effect of suppressing scattering dust other than the effect of land covering. Through this study, it was possible to know about the generation and suppression effect of scattering dust according to crop cultivation.
This study aimed to examine cucumber (Cucumis sativus) varieties adaptive to the desert climate by comparing and analyzing the growth, yield, and water consumption. Two long-sized cucumber varieties, ‘Gulfstream’ and ‘Imea’ and two medium-sized cucumbers, ‘Nagene’ and ‘Sausan’ were cultivated in coir substrate hydroponics under hot and humid greenhouse conditions from March 2 to June 20, 2020. On the 113 DAT, ‘Nagene’ had the longest plant height and the highest internode number. The marketable fruit number per plant was higher in the medium-sized varieties, which had more internode number. The marketable fruit number was 31.3 for ‘Gulfstream’, 30.7 for ‘Imea’, 57.8 for ‘Nagene’, or 56.0 for ‘Sausan’ with no significant difference in total fruit weights per plant. The water consumption required to produce 200 g of fruit was lower in the ‘Nagene’ (2.39 L) with the highest water use efficiency (WUE). Therefore, ‘Nagene’ variety may have higher adaptability to desert high temperature compared to the long-sized varieties, and it is going to be necessary to verify more medium-sized cucumber varieties.
Bulbophyllum auricomum Lindl. is a rare orchid and has flowers with an attractive fragrance. The present study investigated the tissue culture method for micropropagation. Capsules derived from artificial self-pollination were obtained for the best seed germination in MS basal medium. Plant growth regulators (1.0 mg·L-1 of BAP and 2.0 mg·L-1 of NAA) were affected by callus induction from subcultured pseudobulb explants. For the callus subculture, different natural plant extracts were tested in 11 treatment media. Among them, MS medium with 150 mL·L-1 of coconut water was generally effective in fresh weight (1.75 ± 0.08) and (3.01 ± 0.20) of callus proliferation and PLBs induction at 1 and 2 months, respectively, followed by an MS combination of 30 g·L-1 of banana and 20 g·L-1 of potato extract. The results of a comparative study of different MS mediums containing plant growth regulators with a natural extract combination and MS medium supplemented with natural extract only showed that MS medium supplemented with a combination of natural extracts (150 mL·L-1 of coconut water) and plant growth regulators (2.0 mg·L-1 of BAP and 1.0 mg·L-1 of NAA) obtained the highest shoot regeneration (3.37 ± 0.17) and (6.41 ± 0.68) after 1 month and 2 months of culturing, respectively.