• Research in Plant Disease
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• v.27 no.3
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• pp.91-98
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• 2021

The current social demand for organic, sustainable, and eco-friendly approaches for farming, while ensuring the health and productivity of crops is increasing rapidly. Biocontrol agents are applied to crops to ensure biological control of plant pathogens. Research on the biological control of white root rot disease caused by a soil-borne pathogen, Rosellinia necatrix, is limited in pears compared to that in apple and avocado. This pathogenic fungus has an extensive host range, and symptoms of this disease include rotting of roots, yellowing and falling of leaves, wilting, and finally tree death. The severity of the disease caused by R. necatrix, makes it the most harmful fungal pathogen infecting the economical fruit tree species, such as pears, and is one of the main limiting factors in pear farming, with devastating effects on plant health and yield. In addition to agronomic and cultural practices, growers use chemical treatments to control the disease. However, rising public concern about environmental pollution and harmful effects of chemicals in humans and animals has facilitated the search for novel and environmentally friendly disease control methods. This review will briefly summarize the current status of biocontrol agents, ecofriendly methods, and possible approaches to control disease in pear orchards.

• Korean Journal of Agricultural Science
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• v.44 no.1
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• pp.23-29
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• 2017

This study was conducted to explore which pollen type could be an effective pollen source for self-incompatible 'Niitaka' pear (Pyrus pyrifolia Nakai), when different pollinizers were to be applied. The pollens of five different pears with similar flowering times were applied to bagged 'Niitaka' flowers grown in Cheonan city, Korea. Pollen types used were of different origins including Korean pears ('Wonhwang' and 'Chuhwangbae'), Japanese pears ('Chojuuro' and 'Okusankichi'), and Chinese pear ('Yali'). Results show that the amount of pollen produced by flowers of each cultivar was the largest in Korean pear 'Wonhwang' (234 g/100 flowers) and the smallest in Japanese pear 'Okusankichi' (126 g/100 flowers). A high proportion of large fruits (> 600 g), 71.4% of total production, was found in the fruits treated with 'Yali' pollen. However, these fruits showed an unfavorable external appearance. Based on individual fruit width differences, 'Chojuuro' treatment produced the smallest difference in fruit diameters (3.2 mm) and 'Yali' treatment' gave the largest (4.8 mm). Also, the difference in fruit length was the largest in 'Yali' (7.5 mm), which also produced the most uneven fruits among the pollinizers used. Meanwhile, the use of pollens of 'Wonhwang' and 'Chuhwangbae' improved productivity by increasing the fruit shape index and the ratio of bigger fruits in total production. Moreover, those pollens also decreased the development of lenticels on fruit skins which gave them a smoother appearance.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.2
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• pp.43-53
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• 2017

This study aims to analyze the effect of typhoons on pear production. Pears are typical fruits that are vulnerable to typhoon damages, so typhoons are negatively associated with pear productivity. However, relatively less pear damages by typhoons in the main pear production area, comparing to the average in Korea, have been reported. The main production area seems to adopt better agricultural techniques or practices to cope with natural disasters such as typhoons. Thus, this study tests the hypothesis that there are differences of production losses due to typhoons between the main pear production area and the rest using the stochastic frontier analysis. The main production area is defined by Location Quotient Index (LQI), and we found that LQI had a significant effect to decrease the productivity losses in the main production areas, which shows that those production areas alleviated the pear production loss due to typhoons.

• Korean Journal of Environmental Biology
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• v.33 no.3
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• pp.345-351
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• 2015

This study was conducted to find out the methodology of carbon budget assessment among soil, atmosphere and plant. Soil respiration, net ecosystem productivity of herbs and net ecosystem productivity of woody plants have been measured in 30 years old pear orchard at Naju. Closed Dynamic Chamber (CDC) method was used to measure soil respiration and net ecosystem productivity of herbs. Net ecosystem productivity of woody plant (pear) was determined by eddy covariance method using the EddyPro (5.2.1) program. As for soil respiration, $429.1mgCO_2m^{-2}h^{-1}$ was released to atmosphere and sensitivity of soil temperature ($Q_{10}$) was 2.3. In case of herbs, respiration was superior to photosynthesis during measurement period. From 20 to 24 Jun 2015, the sum of absorbed and released $CO_2$ by herb's photosynthesis and respiration was $156.1mgCO_2m^{-2}h^{-1}$. Woody plants showed the $680.1mgCO_2m^{-2}h^{-1}$ of absorption by photosynthesis. In a farm scale, the sum of soil respiration, and net ecosystem productivity of herbs and woody plants was $0.04tonCO_2ha^{-1}$ during the measurement period, and it showed that pear orchard act as a $CO_2$ sink. This study using various approaches is expected to present a methodology for evaluating the carbon budget of perennial woody crop plantations.

• Horticultural Science & Technology
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• v.35 no.4
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• pp.393-401
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• 2017

One-year old pear (Pyrus pyrifolia L.) trees of a new commercial cultivar 'Manpungbae', recently developed in South Korea, were planted in 2001 (planting year 1) and trained to four trellis systems: Y-trellis, Y-II-trellis, pergola, and vase-pergola. To evaluate training systems in the local area (southern Korea), tree growth responses were compared for each trellis system from planting years 3 to 8. For trees trained to Y-trellis and pergola systems, a high proportion of land covered by tree canopy was maintained over the study duration, with 70-80% coverage in year 8. Eight-year cumulative yield per tree was increased in the vase-pergola system with a low planting density and an additional scaffold. Compared with other systems, cummulative yield use efficiency was greatest in Y-II-trellis and pergola systems in years 5 and 8. Compared with Y-II-trellis and vase-pergola systems, the 8-year cumulative yield per hectare was two fold greater for trees trained to the Y-trellis (103 tons) and pergola systems (101 tons). Use of the pergola system improved average fruit weight and fruit soluble solid contents, as well as net income in year 8. Given that we observed reduced fruit productivity and increased labor hours (pruning and orchard work), we consider the Y-trellis and pergola systems to be less valuable trellis systems than the others evaluated.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.497-505
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• 2023

This study evaluated the impact of rain shelters made of plastic film on spring frost damage and fruit quality in Asian pears ('Niitaka') over two years. In 2021, during the coldest spring days (between 0:00 am and 7:00 am), temperatures dropped to -1.20 - 0.43℃ at 120 cm and -1.33 - 0.57℃ at 200 cm above ground level in the control. Conversely, the rain shelter treatment maintained higher temperatures, -0.40 - 0.87℃ at 120 cm and -0.43 - 0.77℃ at 200 cm. Flower damage was significantly lower in the rain-sheltered group, with incidences of 1.3 and 6.9% at 120 and 200 cm, respectively, compared with 18.1 and 22.6% in the control group. Visual observations verified the prevention of frost adhesion on flower organs in the sheltered group, compared with noticeable pistil death and petal browning in the control group. In 2022, when temperatures remained above 0℃, fruitlet stalk length was 5 - 6 mm longer in the sheltered group. The cumulative impact of rain shelters was evident in the improved fruit quality over the two years. This study suggests resilient cultivation strategies in the face of climate change to reduce frost damage, increase productivity, improve fruit quality, and potentially increase incomes of the farmers.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.257-263
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• 2016

Objective of this study was to evaluate the carbon budget on 40 years old pear orchard at Naju. For carbon budget assessment, we measured the soil respiration, net ecosystem productivity of herbs, pear biomass and net ecosystem exchange. In 2015, pear orchard released about $25.6ton\;CO_2\;ha^{-1}$ by soil respiration. And $27.9ton\;CO_2\;ha^{-1}$ was sequestrated by biomass growth. Also about $12.6ton\;CO_2\;ha^{-1}$ was stored at pruning branches and about $5.2ton\;CO_2\;ha^{-1}$ for photosynthesis of herbs. As a result, 25.6 ton of $CO_2$ per ha is annually released to atmosphere. At the same time about 45.7 ton of $CO_2$ was sequestrated from atmosphere. When it sum up the amount of $CO_2$ release and sequestration, approximately $20.1ton\;CO_2\;ha^{-1}$ was sequestrated by pear orchard in 2015, and it showed no significant differences with net ecosystem exchanges ($17.8ton\;CO_2\;ha^{-1}\;yr^{-1}$) by eddy covariance method with the same period. Continuous research using various techniques will help the understanding of $CO_2$ dynamics in agroecosystem and it can be able to present a new methodology for assessment of carbon budget in woody crop field. Futhermore, it is expected that the this study can be used as the basic data to be recognized as a carbon sink.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.828-832
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• 2013

To report country-specific carbon and nitrogen stocks data in a pear orchard by Tier 3 approach of 2006 IPCC guidelines for national greenhouse gas inventories, an experimental pear orchard field of the Pear Research Station, National Institute of Horticultural & Herbal Science, Rural Development Administration, Naju, Korea ($35^{\circ}01^{\prime}27.70N$, $126^{\circ}44^{\prime}53.50^{\prime\prime}E$, 6 m altitude), where 15-year-old 'Niitaka' pear (Pyrus pyrifolia Nakai cv. Niitaka) trees were planted at a $5.0m{\times}3.0m$ spacing on a Tatura trellis system, was chosen to assess the total amount of carbon and nitrogen stocks stored in the trees and orchard soil profiles. At the sampling time (August 2012), three trees were uprooted, and separated into six fractions: trunk, main branches, lateral branches (including shoots), leaves, fruits, and roots. Soil samples were collected from 0 to 0.6 m depth at 0.1 m intervals at 0.5 m from the trunk. Dry mass per tree was 4.7 kg for trunk, 13.3 kg for main branches, 13.9 kg for lateral branches, 3.7 kg for leaves, 6.7 kg for fruits, and 14.1 kg for roots. Amounts of C and N per tree were respectively 2.3 and 0.02 kg for trunk, 6.4 and 0.07 kg for main branches, 6.4 and 0.09 kg for lateral branches, 6.5 and 0.07 kg for roots, 1.7 and 0.07 kg for leaves, and 3.2 and 0.03 kg for fruits. Carbon and nitrogen stocks stored between the soil surface and a depth of 60 cm were 138.29 and $13.31Mg{\cdot}ha^{-1}$, respectively, while those contained in pear trees were 17.66 and $0.23Mg{\cdot}ha^{-1}$ based on a tree density of 667 $trees{\cdot}ha^{-1}$. Overall, carbon and nitrogen stocks per hectare stored in a pear orchard were 155.95 and 13.54 Mg, respectively.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.591-597
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• 2015

We determined the total C and N stocks in trees and soils after 1 year of fertilization in an experimental orchard with 16-year-old 'Niitaka' pear (Pyrus pyrifolia Nakai cv. Niitaka) trees planted at $5.0m{\times}3.0m$ spacing on a Tatura trellis system. Pear trees were fertilized at the rate of 200 kg N, 130 kg P and $180kg\;K\;ha^{-1}$. At the sampling time (August 2013), trees were uprooted, separated into six fractions [trunk, main branches, lateral branches (including shoots), leaves, fruit, and roots] and analyzed for their total C and N concentrations and dry masses. Soil samples were collected from 0 to 0.6 m in 0.1 m intervals at 0.5 m from the trunk, air-dried, passed through a 2-mm sieve, and analyzed for total C and N concentrations. Undisturbed soil core samples were also taken to determine the bulk density. Dry mass per tree was 5.6 kg for trunk, 12.0 kg f or m ain branches, 15.7 kg for lateral branches, 5.7 kg for leaves, 9.8 kg for fruits, and 10.5 kg for roots. Total amounts of C and N per tree were respectively 2.6 and 0.02 kg for trunk, 5.5 and 0.04 kg for main branches, 7.2 and 0.07 kg for lateral branches, 2.6 and 0.11 kg for leaves, 4.0 and 0.03 kg for fruit, and 4.8 and 0.05 kg for roots. Carbon and N stocks stored in the soil per hectare were 155.7 and 14.0 Mg, respectively, while those contained in pear trees were 17.8 and $0.2Mg{\cdot}ha^{-1}$ based on a tree density of 667 trees/ha. Overall, C and N stocks per hectare stored in the pear orchard were 173.6 and 14.2 Mg, respectively. Compared with results obtained in 2012, the amounts of C stocks have increased by $17.7Mg{\cdot}ha^{-1}$, while those of N stocks remained virtually unchanged ($0.66Mg{\cdot}ha^{-1}$).

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.779-786
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• 2012

Many farmers have been seeking alternatives to chemical fertilizer for successful organic fruit production. This experiment was carried out to investigate the replaceability of chemical fertilizer by cover crop and slurry composting biofiltration (SCB) liquid manure (LM) application in pear orchard. Three treatments were contained in this experiment; cover crop only and cover crop + LM treatment, and control (chemical fertilizer application). Dry weight and mineral contents of gramineous cover crops were significantly increased in LM-combined treatments than that of leguminous species. Bulk density of soil was decreased in rye + LM and hairy vetch + LM treatments, compared with each cover crop treatment. Soil pH was lowest in fertilizer treatment and soil nitrate content became similar between treatments after rainy season. Available soil phosphate was lower in cover crop and cover crop + LM treatmemts than control, but exchangeable Mg was higher. The mineral content and net assimilation rate of leaves showed no difference between the treatments. As a result, it is suggested that the application of SCB liquid manure in pear orchard managed by cover crops is desirable to maintain the productivity by improving soil physical properties and potential nutrient recovery.