• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.20
• /
• pp.27-62
• /
• 1975

These studies were aimed at clarifying whether or not selecting agronomic characteristics of hybrid-rice populations under greenhouse conditions was useful. The selection of two quantitative characteristics, culm length and heading date, and two qualitative characteristics, shattering and awnedness, was very effective, but the flag leaf length and the exsertion of panicle was not consistent, varying from one cross to another.

• Journal of Bio-Environment Control
• /
• v.24 no.3
• /
• pp.196-201
• /
• 2015

This study was conducted to seek optimum sowing time and pinching height for tender shoots production of moloheiya (Corchorus olitorius L.), which is a subtropical leaf vegetables, under an unheated greenhouse in the south of Korea. Seeds of moloheiya did not germinate at all at $10^{\circ}C$, but germinated well at $18{\sim}30^{\circ}C$ with 95.5~98.5% germination rate. Germination rate was 75.0% at $15^{\circ}C$, but germination speed was very low. The pods of moloheiya sown before April 28 was matured after late-August, but those sown after May 7 was not matured in that year. In tender shoot production and harvest frequency, treatment sown on April 14 was most plentiful among sowing time treatments, and showed marketable yield increase by 14~42% compared to other sowing times. Mean-while, pinching at 100cm high from soil surface was more effective than other heights for increment of branches and tender shoot. All above suggest that it was suitable to sow seed on mid-April and to pinch at 100cm high from soil surface for increment of tender shoots in the south of Korea.

• Horticultural Science & Technology
• /
• v.33 no.4
• /
• pp.479-485
• /
• 2015

This study was conducted to study the factors inducing micro-cracking and determine proper practices to reduce its occurrence in 'Mansoo' pear fruits. Micro-cracking was observed on ripe fruits. Occurrence of micro-cracking was closely related to sun duration time in August. Micro-cracking occurred severely with shorter sun duration, but weakly with longer sun duration and continuous sunlight. Micro-cracking fruits occurred more frequently in trees with a pergola training system than in those with Y-trellis, but there was no difference between the irrigated and non-irrigated groups. While no micro-cracking was observed without fruit bagging, micro-cracking occurred in fruits with black and yellow outer paper bagging at rates of 62.2 and 17.3%, respectively. Our results suggest that the light condition was the most important cause of micro-cracking because the occurrence of micro-cracking in 'Mansoo' fruits was affected by factors including sun duration, trellis system and fruit bag color. We suggested that micro-cracking could be reduced in 'Mansoo' fruit by optimizing the light conditions with the proper trellis system, bagging color and summer pruning.

• Korean Journal of Soil Science and Fertilizer
• /
• v.22 no.2
• /
• pp.138-145
• /
• 1989

Little information is available on the effects of low pH on nodulation and growth of subterranean clover cultivars. Plants of 11 cultivars were inoculated with an acid-tolerant strain of Rhizobium trifolii and grown for 28 days in continuously flowing nitrogen-free nutrient solutions maintained at six constant pH values from 4.0 to 6.5. At pH 4.0, 4 cultivars failed to nodulate and the remainder formed only a few nodules; nodulation was delayed by 2 to 3 days in this treatment. All cultivars nodulated at pH 4.5 but, with the exception of cv. Dwalganup, nodule numbers were significantly less than at $pH{\geq}5.0$. Only in cvv. Clare and Woogenellup were nodule numbers significantly greater at pH 6.5 than at 5.0. Whole plant dry matter yields were strongly depressed at pH 4.0(21 to 33% of maximum). At pH 4.5, relative yields of all cultivars except Dwalganup were significantly depressed without significant reductions in nodule dry weights, suggesting that nodule function was inhibited by acidity. These results are consistent with the view that nodulation and growth of plants dependent on symbiotic nitrogen fixation are much more sensitive to low pH per se than is host plant growth in the presence of adequate mineral nitrogen.

• Horticultural Science & Technology
• /
• v.35 no.3
• /
• pp.381-386
• /
• 2017

'Jangha' is a new strawberry (Fragaria ${\times}$ ananassa Duch.) cultivar, which was released by the Highland Agriculture Research Institute in 2014. The 'Jangha' cultivar originated in 2008 from a cross between 'Goha' and 'Elsinore' that showed excellent ever-bearing characteristics, including continuous flowering habit and high soluble-solids contents under long-day and high temperature conditions. This cultivar was initially named 'Saebong No. 6' after examining its characteristics and productivity in summer culture from 2010 to 2012. After two regional adaptability tests in 2013-2014, 'Jangha' was selected from Saebong No. 6 as an elite cultivar. The general characteristics of 'Jangha' include semi-spreading type, elliptical leaves, and moderately vigorous growth. The fruit are conical in shape, and red in color. 'Jangha' plants have 21.4 leaves, 55.8 fewer than 'Flamenco' plants. The soluble-solids content of 'Jangha' was 8.9%, which was 1.2% higher than that of 'Flamenco'. The average fruit weight of 'Jangha' was about 11.7g and the marketable yield was $19,013kg{\cdot}ha^{-1}$, 141% higher than 'Flamenco'. 'Jangha' is suitable for summer season cultivation as a high soluble solids contents cultivar, because it shows continuous flowering habit under long-day and high temperature conditions.

• Korean Journal of Organic Agriculture
• /
• v.20 no.1
• /
• pp.49-58
• /
• 2012

Greenhouse whitefly, $Trialeurodes$ $Vaporariorum$, is the most important insect pest in environmental friendly tomato production. Natural enemies, $Nesidiocoris$ $tenuis$ and environmental friendly agricultural materials (EFAM) are major control agents in Korea. The aim of the present work is to evaluate release time of $N.$ $tenuis$ in controlling of $T.$ $vaporariorum$ and to select environmental friendly agricultural materials (EFAM) to suppress both $T.$ $vaporariorum$ and $N.$ $tenuis$ which if the density were high causing necrotic rings. Six EFAM selected to control of $Trialeurodes$ $Vaporariorum$ in three times spray with seven days intervals. Three EFAM showed high mortality 67.7-70.5% in spray after release plot but low in release after spray plot. It should be careful to spray with $N.$ $tenuis$. When $N.$ $tenuis$ were early release at 7 days after transplanting which before occurring and establishment of greenhouse whitefly, it could suppress the density. Extracts of bead tree + matrin, matrin 1, Chrysanthemum showed high mortality on $T.$ $vaporariorum$ adults and $N.$ $tenuis$. The results suggested that this three EFAM could be control agents of the damage of necrotic rings from $N.$ $tenuis$.

• Korean Journal of Environmental Agriculture
• /
• v.34 no.3
• /
• pp.223-229
• /
• 2015

BACKGROUND: It is important to understand residual patterns of pesticides applied on crops for ensuring their safety in agricultural products. However, there are few studies on the residual patterns of pesticides in minor crops, which are small in cultivation area. In this study, residual amounts of bifenthrin and chlorfenapyr sprayed on perilla leaf as a minor crop were investigated to know their residual patterns. METHODS AND RESULTS: Bifenthrin and chlorfenapyr were sprayed 2 or 3 times on perilla leaves at a week interval prior to harvest, and the perilla leaves were collected at 0, 1, 3, 5 and 7 days after the final application of pesticides. Recoveries for residual analysis of pesticides spiked on perilla leaves with concentrations of 0.1 and 0.5 mg/kg were 81.9-104.8%. The residual amounts of pesticides interpreted using first order kinetics model show that dissipation constants of bifenthrin and chlorfenapyr in perilla leaves were 0.0724-0.0535 and $0.0948-0.0821day^{-1}$, respectively. In addition, the dissipation half-lives in perilla leaves were 9.6-12.9 days for bifenthrin and 7.3-8.4 days for chlorfenapyr. When pre-harvest residue limits (PHRL) of bifenthrin and chlorfenapyr at 10 days before harvest calculated on the basis of the dissipation constants and maximum residue limits of the pesticides were calculated as 17.1 for bifenthrin and 15.9 mg/kg for chlorfenapyr. CONCLUSION: Therefore, the PHRL calculated using the time-dependant residual patterns of pesticides in perilla leaves and their regression analysis may be used as experimental evidences in order to ensure the safety of pesticides in perilla leaves before harvest.

• Journal of Bio-Environment Control
• /
• v.28 no.1
• /
• pp.9-15
• /
• 2019

This study aimed to examine the effects of different degrees of defoliation during harvest season on hydroponically cultured 'Seolhyang' strawberry's fruit characteristics, plant growth, and changes in nonstructural carbohydrates, and find an effective defoliation method. On November 29, 2013, some of the 'Seolhyang' leaves were non-defoliated and the others were defoliated remaining 9 and 5 leaves. The number of fruits and fruit weight were not significantly different in the first flower cluster but in the second, third, and fourth flower clusters decreased as the level of defoliation increased. The soluble solids content and acidity of fruits decreased in all the clusters as the level of defoliation increased. The leaf area and leaf dry weight of strawberry plant in all the treatment groups decreased from January to March and root dry weight sharply decreased during February. Thereafter, during April, the growth of plant increased. As defoliation increased, the dry weight of fruits, flower clusters, crowns, and roots decreased, and during late growing period, difference in dry weight according to the degree of defoliation was considerable. The content of carbohydrate was greater in the leaves than the fruits excepting January 30 and February 28, 2014 and in the case of strawberry plant that continuously produce fruits, the content of carbohydrate decreased in the leaves and roots. As defoliation increased, the content of carbohydrate in fruits, flower clusters, crowns, and roots decreased. Defoliation for strawberry plants is carefully done during harvest season. Twelve leaves during December and 14 leaves from January to March should be maintained, and in April when the number of leaves increases, old leaves should be defoliated.

• Journal of Convergence for Information Technology
• /
• v.10 no.12
• /
• pp.201-207
• /
• 2020

In this study, the practicality of unmanned aerial vehicle photography information was identified. Therefore, a total of four consecutive surveys were conducted on the field-level survey areas among the areas subject to photography using unmanned aerial vehicles, and the changes in crop conditions were analyzed using pictures of unmanned aerial vehicles taken during each survey. It is appropriate to collect and utilize photographic information by directly taking pictures of the survey area according to the time of the on-site survey using unmanned aerial vehicles in the field layer, which is an area where many changes in topography, crop vegetation, and crop types are expected. And it turned out that it was appropriate to utilize satellite images in consideration of economic and efficient aspects in relatively unchanged rice paddies and facilities. If the survey area is well equipped with systems for crop cultivation, deep learning can be utilized in real time by utilizing libraries after obtaining photographic data for a certain area using unmanned aircraft in the future. Through this process, it is believed that it can be used to analyze the overall crop and shipment volume by identifying the crop status and surveying the quantity per unit area.

• Journal of Bio-Environment Control
• /
• v.33 no.1
• /
• pp.45-54
• /
• 2024

A proper level of UV-A light treatment in terms of intensity, spectrum, and exposure duration is known to have a positive impact on plant growth, photosynthesis, and the biosynthesis of secondary metabolites. However, there are few studies investigating the physiological responses of spinach (Spinacia oleracea L.) to UV radiation. Hence, this study aimed to assess the effects of short-term UV-A radiation on the growth and bioactive compounds of spinach. Spinach seedlings were cultivated in a vertical farm module under the following environmental conditions: photosynthetic photon flux density 200 µmol·m^-2·s^-1, white LED, 12 h on/off, 20℃ air temperature, 70% relative humidity, and 500 µmol·mol^-1 CO₂ concentration. After 5 weeks of sowing, the seedlings were subjected to continuous UV-A (peak wavelength; 385 nm) irradiation at two different energy levels: 20 W·m^-2 and 40 W·m^-2 for 7 days. As a result, the UV-A_20W treatment increased the shoot fresh and dry weights of spinach. However, there were no significant differences observed in photosynthetic parameters between the UV-A treatments and the control. The maximum quantum efficiency of photosystem II (Fv/Fm) consistently decreased across all UV-A treatments for 7 days in UV-A treatments. Additionally, the total phenolic content and antioxidant capacity increased in the UV-A_20W treatment at 7 days of treatment as well as the total flavonoid content significantly increased at 5 and 7 days of treatment. These findings suggest that supplemental UV-A LED radiation can enhance the growth and quality of spinach cultivated in closed type plant production systems such as vertical farms.