• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.66 no.1
• /
• pp.8-17
• /
• 2021

As rice originates from tropical regions, low temperature stress during the germination stage in temperate regions leads to serious problems inhibiting germination and seedling establishment. Identifying and characterizing quantitative trait loci (QTLs) for low-temperature germination (LTG) resistance help accelerate the development of rice cultivars with LTG tolerance. In this study, we identified QTLs for LTG tolerance (qLTG5, qLTG9) and germination coefficient of velocity under optimal conditions (OGCV) (qOGCV7, qOGCV9) using 129 recombinant inbred lines (RILs) derived from the cross between a low-temperature sensitive line Milyang23 and a low-temperature tolerant variety Gihobyeo. qLTG9 and qOGCV9 were detected at the same location on chromosome 9. At both LTG QTLs (qLTG5 and qLTG9), the alleles for LTG tolerance were contributed by the japonica variety Gihobyeo. At qOGCV7 and qOGCV9, the alleles for low temperature tolerance were derived from Milyang23 and Gihobyeo, respectively. The RILs with desirable alleles at two or more QTLs, i.e., GroupVII: qLTG5+qLTG9 (qOGCV9) and GroupVIII: qLTG5+qOGCV7+qLTG9 (qOGCV9), showed stable tolerance under low-temperature stress. Our results are expected to contribute to the improvement of tolerance to low-temperature and anaerobic stress in japonica rice, which would lead to the wide adoption of direct-seeding practices.

• Korean journal of applied entomology
• /
• v.24 no.1 s.62
• /
• pp.25-28
• /
• 1985

Experiments were carried out to investigate the life cycle of the rice leaf beetle (RLB), (Oulema oryzae KUWAYAMA) ,yield losses by its damages, and control method in $1976{\sim}1983$ at the experimental field of Gangweon PORD. Peak occurrence of adult and larva rice beetle was late May and mid-June, respectively. Adult overwintered in the forest of mountain and move into the paddy field to lay eggs on the rice leaf from late seedling stage. A female adult laid eggs for 2 days, and egg, larval and pupal period was 9, 16, and 9 days, respectively. Leersia japonica MAKINO was damaged slightly by the beetle. The yield reduction by artifical defoliation ranged from 6 to 40% and yield reduction increased as leaf feeding delayed until mid-July. All insecicides show 100% of control value against RLB.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.325-325
• /
• 2017

In the 20th century, the average temperature of Korea has risen by $1.5^{\circ}C$, whereas it has risen by $0.6^{\circ}C$ globally. Few studies have investigated the effect of seeding date in hilly pastures on their growth characteristics and productivity. The purpose of this study was to elucidate the effect of seeding dates at a hilly pasture establishment on its growth characteristics and productivity caused by increasing temperatures in Korea. The experiments were conducted from 2014 to 2016 at Pyeongchang, South Korea, at an altitude 600-700 m above sea level. The composition of grass mixture was tall fescue, orchard grass, perennial ryegrass, Kentucky bluegrass, timothy, and white clover. Treatments comprised four seeding dates (August 13 and 27, and September 10 and 24). The establishment rate was lowest on September 24, resulting in only 20% establishment over the winter, and the proportion of weeds was highest on September 24 (58%). Early seedling growth before overwintering is a critical approach to ensure successful establishment of grassland. The main components were orchard grass and tall fescue on the early seeding date (August 13), and Kentucky bluegrass on the late seeding date (September 24). Late seeding increased the proportion of bare lands invaded by weed species, especially during second and third cutting periods. Early seeding date resulted in a progressive increase in biomass. Total annual production was significantly affected by the seeding date; lowest dry matter production was on September 24 ($2,441kg\;ha^{-1}$), whereas maximum dry matter yield was on August 27 ($6,608kg\;ha^{-1}$). The results of the study indicate that growth condition and productivity could be increased by early seeding, and seeding of grass in the Pyeongchang area should be completed before August 27. However, further studies are needed to determine the ideal seeding date at the hilly pasture establishment in Pyeongchang.

• Korean Journal of Environmental Agriculture
• /
• v.39 no.1
• /
• pp.50-57
• /
• 2020

BACKGROUND: Biochar is used in various environmental fields, such as water quality and soil restoration, and affects soil fertility and nutrient cycling. Also, when crops are grown on biochar-applied soil, their characteristics may be affected. Biochar is used especially with commercial vegetable seedlings. METHODS AND RESULTS: The objective of this study was to determine the effects of biochar content in seeding mixes on early growth of lettuce (Lactuca sativa L.), Chinese cabbage (Brassica rapa L.), and red pepper (Capsicum annuum L.). Treatments consisted of a control (0: 10, ratio of biochar to seeding mixes (w/w)), 1: 9 (biochar 10%), 3: 7 (biochar 30%), 5: 5 (biochar 50%), and 7: 3 (biochar 70%). The biochar was made from risk husk and had a C/N ratio of 104. As the mixing ratio of biochar increased, pH increased whereas EC and nitrogen content decreased. The highest phosphorus content was with the treatment of 30% biochar, while there were significant increases in the weight of lettuce seedlings and concentrations of T-N, P₂O₅, K₂O, MgO, and Na with the treatments of 30% and 50% biochar. Although the weight of Chinese cabbage seedlings increased with the treatment of 10% biochar, the increase was not statistically significant. Also, there was an increase in the weight of red pepper seedlings with the treatment of 30% biochar, but the increase was not statistically significant. With increases in the biochar mixing ratio, the K₂O concentration of red pepper seedlings increased, but the concentrations of P₂O₅, CaO, MgO, and Na decreased. It was believed that this was because of absorption inhibition by calcium-phosphate formation in the seeding mixes owing to increased pH. CONCLUSION: In conclusion, adding biochar to seeding mixes is considered to be an important mean for growing healthy vegetable seedlings. More field experiments are needed to verify the effect of biochar on vegetable crop growth over the entire growing season.

• The Korean Journal of Malacology
• /
• v.17 no.2
• /
• pp.79-84
• /
• 2001

In order to obtain the basic information for seedling production of the scallop, Patinopecten yessoensis, the egg development and larva growth were investigated at different conditions such as water temperature, salinity and phytoplankton. Eggs were demersal isolated eggs, which averaged 77.3${\pm}$2.7$\mu\textrm{m}$ in diameter after spawning. The fertilized eggs developed to D-shaped larva of shell length 117.5${\pm}$3.8$\mu\textrm{m}$ after 60 hours at 15$^{\circ}C$. The range of water temperature and salinity during egg development were 10-20$^{\circ}C$ and 28-34 ppt, respectively. The time of egg development was shorter with higher water temperature. After 10 days of spawning, D-shaped larva reached 160 $\mu\textrm{m}$ in shell length, and after 25 days became full-grown larva 250 $\mu\textrm{m}$ in shell length, in which could be observed eye spots. The relative growth formula between shell length (SL) and shell height (SH) was SH = 1.0425SL-27.731 (r$^2$= 0.9749) during the entire larva period. In regard to water temperature, growth and survival rates of larvae were good at 16$^{\circ}C$. Lower growth and survival rates were observed at 12$^{\circ}C$ and 20$^{\circ}C$ than that at 16$^{\circ}C$. When larvae were fed mixed phytoplankters, such as isochrysis galbana, Pavlova lutheri and Chaetoceros calcitrans, their growth and survival rates were the highest among groups.

• Horticultural Science & Technology
• /
• v.33 no.5
• /
• pp.784-788
• /
• 2015

A new cultivar 'Picnic' originated from an artificial cross between 'Fuji' and 'Sansa' at National Institute of Horticultural & Herbal Science in 1994. The cultivar was preliminarily selected among the elite siblings for its high fruit quality in 2003. After regional adaptability tests in five districts for four subsequent years as 'Wonkyo Ga-34', it was ultimately selected in 2008. Optimum harvest time is late September. Mature fruit has mean weight of 233 g and is conic with light red skin on a greenish yellow ground and yellowish white flesh. The fruit contains a favorable total soluble solids content at $13.8^{\circ}Brix$ and titratable acidity at 0.43%, which results in gustatory harmony between sugars and acids. It is not resistant to bitter rot or Marssonina blotch. 'Picnic' exhibits a physiological cross compatibility with leading cultivars such as 'Fuji', 'Hongro' and 'Tsugaru'. Tree topology is semi-spreading with a weak growth habit.

• Korean Journal of Plant Resources
• /
• v.32 no.4
• /
• pp.296-302
• /
• 2019

This study was accomplished to select breeding materials among the pear germplasm 6 species 43 accessions and check out the expression of scab incidence of inter specific hybrids of 5 crosses 609 seedlings for scab resistance breeding. Fruitlets scab incidence of P. pyrifolia, P. bretschneideri and P. ussuriensis were 59.5, 73.4 and 63.0% respectively, and also fruitlets scab incidence of interspecific hybrid cultivars between P. pyrifolia and P. bretschneideri were 77.7%. However, fruitlets scab incidence of P. communis and interspecific hybrid accessions between P. pyrifolia and P. communis were significantly less than 15%. As a result of the Duncan test, scab resistance of pear accessions were classified into two groups: P. communis and their hybrid were resistance and P. bretschneideri, P. pyrifolia, P. ussuriensis, and among their hybrid were susceptible. Also, it showed the same trend in the seedlings. Scab incidence of 'Seolwon' ${\times}$ 'Chuwhangbae' and 'Supergold' ${\times}$ 'Mantienhong' in P. pyrifolia seedlings showed more than 80%, while that of interspecific hybrid between P. pyrifolia and P. communis showed about 2%. It showed scab resistance of P. communis transferred to hybrid seedlings and expressed to be dominant in their seedlings. Namely, P. communis was good breeding materials for scab resistance.

• Research in Plant Disease
• /
• v.26 no.4
• /
• pp.256-263
• /
• 2020

Incidence of Fusarium wilt was surveyed in fields of summer radish in Gangwon province in Korea in 2018 and 2019. The disease started in early July and spread rapidly in hot summer of late July and August and in severe case, reached up to 80% in a field in Gangneung area. Symptoms in the seedling stage include poor growth and browning of internal tissue of root. During mid-growth, the leaves of diseased plant turned yellow over time, the surface of the roots changed from white to blackish, and the vascular tissues turned brown. A total of 23 isolates was obtained from the diseased plants and identified as Fusarium oxysporum f. sp. raphani by elongation factor-1α and intergenic spacer sequence analysis. Pathogenicity of the isolates was tested by artificial inoculation to the radish and other plants. All the isolates tested were pathogenic to radish plant, although there were differences in virulence on radish 11 cultivars. However, the isolates were not virulent to other plants except some cruciferous vegetables including Brussels sprouts, rocket, stock, and turnip. The results of pathogenicity test showed that it is necessary to rotate with crops other than cruciferous vegetables in order to prevent Fusarium wilt from radish fields.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.42 no.2
• /
• pp.108-113
• /
• 2022

Arsenic (As) uptake and accumulation from agricultural soil to rice vary depending on the soil environmental conditions such as soil pH, redox potential, clay content, and organic matter (OM) content. Therefore, these factors are important in predicting changes in the uptake and accumulation of As in rice plants. Here, we studied the chemical properties of As-contaminated and/or rice straw compost (RSC)-treated soils, the growth responses of RSC-applied rice plants under As-contaminated soils, the changes in As content of soil, and the relationship between As uptake and accumulation from the RSC-treated soils to the rice organs under As-contaminated soils. Rice plants were cultivated in 30 mg kg^-1 As-contaminated soils under three RSC treatments: 0 (control), 12, and 24 Mg ha^-1. No significant differences were indicated in the chemical properties of pre-experimental (before transplanting rice seedling) soils, with the exception of EC, OM, and available P₂O₅. As the treatment of RSC under 30 mg kg^-1 As-contaminated soils increased, EC, OM, and available P₂O₅ increased proportionally in soil. Increased soil RSC under As-contaminated soils increased shoot dry weight of rice plants at harvesting stage. As content in roots increased proportionally with RSC content, whereas As content in shoots decreased under As-contaminated soil at all stages of rice plants. Nevertheless, As accumulation were significantly decreased in both roots and shoots of RSC-treated rice plants than those in the plants treated without RSC. These results indicate that the use of RSC can mitigate As phytotoxicity and reduce As accumulation in rice plants under As-contaminated soils. Therefore, RSC can potentially be applied to As-contaminated soil for safe crop and forage rice production.

• Horticultural Science & Technology
• /
• v.34 no.5
• /
• pp.727-735
• /
• 2016

This research was conducted to investigate the influence of various pre-planting $NO_3:NH_4$ ratios in the coir dust+peatmoss+perlite (3.5:3.5:3, v/v/v) medium on the growth of tomato plug seedlings (cv. Dotaerang Dia), changes in chemical properties of root media, and tissue nutrient contents. With the fixation of N concentration to $300mg{\cdot}L^{-1}$, the $NO_3:NH_4$ ratios were adjusted to 100:0, 73:27, 50:50, 27:73, 0:100. Then, root media containing various $NO_3:NH_4$ ratios and equal concentration of other essential nutrients were filled into 50-cell plug trays and the seeds of 'Dotaerang Die' tomato were sown. The investigation of seedling growth and tissue analysis for mineral nutrient contents based on the dry weight of above-ground tissue were conducted 6 weeks after sowing. As seedlings grew, the EC decreased quickly and pH increased gradually in the all treatment media. The plant height, fresh weight and dry weight of seedlings in the treatment of 50:50 ($NO_3:NH_4$) were 29.0 cm, 13.7 g, and 1.21 g, respectively, which were the highest among treatments tested. However, the seedlings in the treatment of 0:100 ($NO_3:NH_4$) had 26.5 cm, 11.2 g, and 0.92 g in plant height, fresh weight and dry weight, respectively. These were the poorest among the treatments tested. The tissue contents of N were 2.77 to 3.22% in all the treatments. The treatment of 27:73 ($NO_3:NH_4$) had the highest contents of Fe, Mn and Zn and that of 0:100 ($NO_3:NH_4$) had the lowest contents of Mg, Na, Cu, Mn and Zn among the treatments tested. The results indicate that $NH_4$ ratio should be lower than 50% in the coir dust+peatmoss+perlite (3.5:3.5:3, v/v/v) medium for seedling growth of tomato and the optimum ratio will be used to draw up guide lines for plug seedling production.