• Journal of Bio-Environment Control
• /
• v.21 no.3
• /
• pp.220-227
• /
• 2012

This study was conducted to analyze the seeding quality of paprika and the growth and early yield after transplanting of paprika nursed under artificial light and natural light. In this study, blue LED, red LED, and white fluorescent lamps (FL) were used as artificial lighting sources. Photoperiod, average photosynthetic photon flux, air temperature, and relative humidity in a closed transplants production system (CTPS) were maintained at 16/8 h, $204{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 26/$20^{\circ}C$, and 70%, respectively. Leaf length, leaf width, leaf area, top fresh weight and dry weight of paprika seedlings, and chlorophyll content in paprika leaves nursed under LED and fluorescent lamps for 21 days after experiment were significantly affected by light treatments. As compared with the control (white FL), leaf area of paprika grown under blue LED, red LED, and natural light was decreased by 63%, 63%, and 28%, respectively. Top dry weight of paprika grown under blue LED, red LED, and natural light was 64%, 50%, and 22%, respectively, compared with the control. Number of leaves on 18 days after transplanting showed with red LED, blue LED, and natural light by 86%, 84%, and 48%, respectively, compared with the control. On 114 days after transplanting, paprika nursed under blue LED and red LED had relatively short plant height. This result might be caused that the elongation of its internodes was suppressed by the illumination of sole blue or red light. Average number of fruits per plant harvested during 4 weeks after first harvest was 3.5 with red LED, 3.3 with blue LED, 1.0 with natural light, and 2.2 with control, respectively. Early yield of paprika nursed under red LED, blue LED, natural light, and control were 453 g/plant, 403 g/plant, 101 g/plant, and 273 g/plant, respectively. Larger fruit of 136 g was harvested with red LED treatment. Even though the early yield of paprika was greatly increased with artificial lighting, but total yield was almost similar as the harvest period after transplanting in greenhouses was lengthened. From the above results, we could understand that paprika nursed under white FL, blue LED, and red LED showed good growth after transplanting and was early harvested by a week as compared to the natural light. Therefore, the white FL, blue LED, and red LED as the artificial lighting sources in CTPS could be strategically used to enhance the seedling quality, to shorten the harvest time, and to increase the yield of paprika.

• Journal of Bio-Environment Control
• /
• v.24 no.3
• /
• pp.235-242
• /
• 2015

The objective of this study was to determine the effects of soluble potassium silicate by soil drenching application on watermelon growth, yield, and nutrient uptake. The potassium silicate rates were control (No potassium silicate), 1.63mM, 3.25mM, 6.50mM. The potassium silicate were treated 6 times (twice before fruit forming and 4 times after fruit forming per 7 day. Soil chemical properties, such as soil pH, EC, available phosphorus and silicate, exchangeable K, nitrate-N levels were increased after potassium silicate treatment, while the concentrations of soil organic matter, exchangeable Ca and Mg were similar to control. The growth characteristics of watermelon, such as stem diameter, fresh and dry weight of watermelon at harvest were thicker and heavier for increased potassium silicate treatment than the control, while number of node, and plant length were same for all treatments. With increased potassium silicate treatment, nutrient concentrations, such as P and K in the watermelon leaf at harvest were increased, N concentration in the leaf was decreased, and Ca and Mg concentrations in the leaf were same. Chlorophyll content was increased with increased potassium silicate application. The occurrence of powdery mildew was lower for the potassium silicate treatments than the control. Fresh watermelon weight for the potassium silicate treatments was 0.1 to 0.5kg per watermelon heavier than the control, sugar content was 0.5 to $0.6^{\circ}Brix$ higher than control, and merchantable watermelon was 2 to 4% increased compared to the control. These results suggest that potassium silicate application by soil drenching method in the greenhouse can improve watermelon nutrient uptake, merchantable watermelon and suppress the occurrence of powdery mildew.

• Journal of Bio-Environment Control
• /
• v.28 no.4
• /
• pp.420-428
• /
• 2019

This study is the heating energy saving test of the high-bed strawberry crown heating system. The system consists of electric hot water boiler, thermal storage tank, circulation pump, crown heating pipe(white low density polyethylene, diameter 16mm) and a temperature control panel. For crown heating, the hot water pipe was installed as close as possible to the crown part after planting the seedlings and the pipe position was fixed with a horticultural fixing pin. In the local heating type, hot water at $20{\sim}23^{\circ}C$ is stored in the themal tank by using an electric hot water boiler, and crown spot is partially heated at the setting temperature of $13{\sim}15^{\circ}C$ by turning on/off the circulation pump using a temperature sensor for controlling the hot water circulation pump which was installed at the very close to crown of strawberry. The treatment of test zone consisted of space heating $4^{\circ}C$ + crown heating(treatment 1), space heating $8^{\circ}C$(control), space heating $6^{\circ}C$ + crown heating(treatment 2). And strawberries were planted in the number of 980 for each treatment. The heating energy consumption was compared between November 8, 2017 and March 30, 2018. Accumulated power consumption is converted to integrated kerosene consumption. The converted kerosene consumption is 1,320L(100%) for space $8^{\circ}C$ heating, 928L(70.3%) for space $4^{\circ}C$ + crown heating, 1,161L($88^{\circ}C$) for space $6^{\circ}C$ + crown heating). It was analyzed that space $4^{\circ}C$ + pipe heating and space $6^{\circ}C$ + crown heating save heating energy of 29.7% and 12% respectively compared to $8^{\circ}C$ space heating(control).

• Korean journal of applied entomology
• /
• v.52 no.4
• /
• pp.437-448
• /
• 2013

Hemipteran bugs, which were previously considered as secondary pests, have currently become important pests of numerous crops. Among them, Riptortus pedestris (Fabricius) is a major species that occurs in Korea, Japan, China, and South Asian countries. Riptortus pedestris infests leguminous crops like soybean, vetches, and red clover; fruit trees like persimmon and yuju; and grains like barley, foxtail millet, broomcorn, and sorghum. Riptortus pedestris causes the greatest damage to soybean, as it is the most suitable host for the bug. Feeding damage during pod formation significantly reduces the yield of soybean. Currently, 17 insecticides, including diazinon and etofenprox, are registered for the control of hemipteran bugs in Korea, and growers apply insecticides two to three times on a regular basis. Aggregation pheromone traps are widely used as a monitoring tool and partial control measure. The aggregation pheromone of R. pedestris attracts conspecific adults and nymphs and is used for food exploitation rather than sexual attraction. In addition, the pheromone serves as a kairomone for egg parasitoids such as Gryon japonicum (Ashmead) and Ooencyrtus nezarae Ishii. As a new method of pest management, nonviable host eggs were included in the pheromone trap to catch R. pedestris and propagate parasitoids. As a part of cultural practices, resistant soybean varieties with specific color and size of pod and control of flowering time through the alteration of planting date can be used. For the effective management of R. pedestris in the near future, development of cultural practices that can support natural control factors and the use of multiple control tactics are needed.

• Korean Journal of Agricultural Science
• /
• v.21 no.2
• /
• pp.81-91
• /
• 1994

This study was conducted to find a potential effect of ethephon or dichlorprop spray on the fruit growth and maturation in 'Niitaka' pears. Chemicals were applied between June 10 to 24 (7-9 weeks after full bloom). Ethephon in the range from 25 ppm to 100 ppm, and dichlorprop from 20 ppm to 40 ppm reduced the fruit size regardless application time and concentration. The fruit growth was more inhibited at the higher concentrations in both chemicals. Flesh firmness was more rapidly decreased in the fruit treated by both chemicals. Firmness at harvest was lowest in the treatment of 100 ppm ethephon. The climacteric increase of ethylene synthesis occurred earlier in the fruit treated by ethephon or dichlorprop regardless application concentrations and the maximum peak of ethylene production was rugher. Total phenolics significantly reduced in fruits treated with ethephon. However, the contents of soluble solids and acid were not affected by ethephon or dichlorprop treatment. Ground color was changed rapidlys by the treatments resulting in the early maturation of fruit. Optimum maturity of fruit was shortened 2-3 days by ethephon and 3-4 days by dichlorporp when maturity was determined on the basis of ground color development and firmness.

• Journal of Applied Biological Chemistry
• /
• v.63 no.3
• /
• pp.267-274
• /
• 2020

The dissipation characteristics and kinetics of fungicide mandipropamid and insecticide thiamethoxam in lettuce under greenhouse conditions were investigated at three different lettuce-growing fields for estimating the pre-harvest residue limits (PHRLs). The analytical methods were fully validated for the quantitation of pesticide residues using High-Performance Liquid Chromatography-Photo Diode Array detector or Ultraviolet-Visible Detector and applied to real samples. The lettuces suitable for shipment were harvested during 10 days including pre-harvest interval after treatment at the recommended dose by safe-use guidelines. The initial mean residues in different fields were 6.68-17.87 and 4.96-8.31 mg/kg for mandipropamid and thiamethoxam, respectively, which decreased to 16-54 and 14-44% in 10 days. The clothianidin, a metabolite of thiamethoxam, was detected in <0.02 to 0.37 mg/kg. The dissipation of both pesticides followed first-order kinetics over a period of 10 days after application. Based on the residue data, the mean dissipation rate constant (λ) and biological half-lives (T_1/2) were estimated to be -0.1060 and 6.5 days of mandipropamid and -0.1236 and 5.6 days of thiamethoxam. The PHRLs for lettuce on the 10th and 5th day before harvesting were calculated to be 63.24 and 43.56 mg/kg for mandipropamid, and 44.66 and 25.88 mg/kg for thiamethoxam, with -0.0746 and -0.1091 of the upper 95% confidence intervals of dissipation rate constant, respectively. This work would be useful as guidance for adjusting the shipment date and contribute to stabilizing the income of farmers in Korea.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.18 no.4
• /
• pp.291-302
• /
• 1998

The purpose of this study is to clarify the effect of plant growth regulator "Uniconazole-P" on the control of growth and seed producrtion of pasture plants under grown in sward conditions. Four species examined were orchard grass, timothy, red clover and alfalfa. Uniconazole-P concentrations were control(0), 20ppm and 40ppm, and foliar sprayed on canopy structures at the floral differentiation stages of grasses and at the begining of flowering stages of legumes, respectively. 1. Yield components and seed yield components of grasses and legumes were responded differently between Uniconazole-P concentrations, species and the stages of growth. 2. At early heading stages, the plant length and culm length of grasses were reduced by Uniconazole-P treatments. On the contrary, the dry weight of ears per area and chlorophyll concentrations were increased by Uniconazole-P treatments. 3. At seed ripening stages, the number of ears, dry weight of a tiller, dry weight of a ear, dry weight of ears per area and dry weight of seeds in orchardgrass, and the number of ears, dry weight of a ear, dry weight of ears per area, dry weight of seeds and harvest index in timothy were increased by Uniconazole-P treatments. 4. At early flowering stages, the plant length and total length of internodes were reduced by Uniconazole-P treatments. On the contrary, total length of branches and chlorophyll concentrations of red clover and alfalfa were increased by Uniconazole-P treatments. Particularly, the number of inflorescences and dry weight of inflorescences of red clover was increased greatly by Uniconazole-P treatments. 5. At seed ripening stages, the plant length of both of legumes were reduced by Uniconazole-P treatments. On the contrary, the dry weight of a inflorescence, dry weight of inflorescences per area, dry weight of seeds and harvest index of alfalfa was increased by Uniconazole-P treatments. 6. Seed production of grasses by Uniconazole-P treatments can be explained as following processes at each stage of growth. 1) reduced in plant length and culm lengths at early heading stages, 2) increased in number of ears and dry weight of a ear at both of stages, and 3) increased in dry weight of ears per area, dry weight of seeds and harvest index at seed ripening stages. 7. Seed production of legumes by Uniconazole-P treatments can be explained as following processes at each stage of growth. 1) reduced in plant length and total length of internodes and increased in number of branches and total length of branches at early flowering stages, 2) increased in number of inflorescences and dry weight of inflorescences at both of stages, and 3) increased in dry weight of seeds and harvest index at seed ripening stages.

• Horticultural Science & Technology
• /
• v.31 no.2
• /
• pp.135-140
• /
• 2013

This experiment was conducted to find the effects of a $GA_3$ and thidiazuron (TDZ) on seedless rate, harvest time, fruit cracking and fruit quality in 'Kyoho' grapes over two years from 2008 to 2009. In 2008, fruit clusters were dip treated with $GA_3$ $25.0mg{\cdot}L^{-1}$ twice at full bloom (FB) and 14 days after full bloom (DAFB) in a combination with TDZ 0 or $2.5mg{\cdot}L^{-1}$. Berry seedless rate and berry enlargement were slightly improved only when TDZ was added to the second $GA_3$ treatment at 14 DAFB, compared to $GA_3$ + TDZ treatments at both FB and 14 DAFB. However, berry cracking rate was significantly increased by any plant growth regulator (PGR) treatments compared to non treatment. In 2009, $GA_3$ at $12.5mg{\cdot}L^{-1}$ and $25.0mg{\cdot}L^{-1}$ was dip treated twice at FB and 14 DAFB while TDZ $2.5mg{\cdot}L^{-1}$ was treated only at 14 DAFB. Berry cracking rate was depended on the concentration of $GA_3$ applied. The higher concentration at $25.0mg{\cdot}L^{-1}$ significantly increased berry cracking rate while the lower concentration at $12.5mg{\cdot}L^{-1}$ had no effect. Also, the addition of TDZ to $GA_3$ $25.0mg{\cdot}L^{-1}$ at 14 DAFB, substantially decreased the cracking rate to the level of untreated control. Although all PGR treatments advanced fruit maturity, the most significant advance occurred when TDZ was added to $GA_3$ $12.5mg{\cdot}L^{-1}$ only at the second dip. Considering the overall aspects related to fruit maturity and quality, we concluded that the double applications of $12.5mg{\cdot}L^{-1}$ $GA_3$ at FB and 14 DAFB with addition of $2.5mg{\cdot}L^{-1}$ TDZ only at 14 DAFB was appropriate to produce about 400-500 g size of seedless 'Kyoho' grape cluster having 35-40 berries.

• Journal of Bio-Environment Control
• /
• v.21 no.3
• /
• pp.294-298
• /
• 2012

In sweet cherry (Prunus avium L.) growing there are several severe problem which have to be overcome to produce highly graded fruits because of fruit rots and fruit crackings, if there is frequent precipitation during immature fruit step and picking season. In order to reduce fungicide sprayings and produce qualified fruits in areas with rainy season like as South Korea, rain-sheltered growing is necessary absolutely. Sweet cherry blooms early to medium April in southern area of South Korea. If we depend on honeybees (Apis mellifera) distributed in natural ecosystem, it is not easy to get normal fruit-set every season because of low temperature around blooming time. And also bee keepers seldom sell honeybee hives as a pollinator during spring, instead they keep honeybee hives to get honey. Recently use of B. terrestris as a pollinator of cherry tomato, oriental pumpkin etc. grown in protected cultivation system increase abundantly. Therefore, in this study we studied B. terrestris as an alternate of honeybee to pollinate sweet cherry grown in rain shelter. In part of foraging activity B. terrestris shows staying on a cherry flower for about six second and visiting frequency of 11 flowers per minute. However A. mellifera stayed about 15 second on a flower and visited 4~5 flowers per minute. There were no significant difference in fruit-setting rate and fruit characteristics after using B. terrestris and A. mellifera as pollinators of sweet cherry. Consequently there is no negative effect when we use B. terrestris as an alternate pollinator of A. mellifera in sweet cherry cultivation under rain shelter.

• Journal of Bio-Environment Control
• /
• v.22 no.3
• /
• pp.209-213
• /
• 2013

This study was conducted to produce heads of artichoke in July in Korea. The artichoke was planted in the Autumn and it could be reaped heads of artichokes in late of May in Korea. It can inform us that the artichoke need under some low temperature during the Winter to open flowers. In order to harvest heads of artichoke in the Summer two kinds of cultivar 'Green Globe' and 'Imperial Star' those were grown for 4 weeks in green house of $17^{\circ}C$ which were treated at 3, 6, 9 and $12^{\circ}C$ chamber for 4 weeks and then planted the 8th April. Plant distance was $150{\times}50$ cm. After 3 months most of artichoke of 'Imperial Star (IS)' made heads. Especially, the artichokes 'IS' were treated at $6^{\circ}C$ made heads 63% of plants but those at $12^{\circ}C$ made heads 33% and the artichokes (no treatment at low temperature) grown in greenhouse at $17^{\circ}C$ for 8 weeks made heads 5% of plants. 'Green Globe (GG)' made heads 28% of plants at $9^{\circ}C$ and 10% at $12^{\circ}C$, and 'GG' grown in greenhouse at $17^{\circ}C$ for 8 weeks never had made any head. The weights of head were 97 g and 86 g in 'IS' and 'GG' respectively. The yield of heads were 215 and 108 kg/10a in 'IS' and 'GG' respectively.