• Korean Journal of Soil Science and Fertilizer
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• v.35 no.5
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• pp.314-325
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• 2002

The effects of arbuscular mycorrhizal (AM) fungus (Glomus intraradices) on plant growth and N metabolic responses were examined in perennial ryegrass plants exposed to drought-stressed or well-watered condition. Mycorrhizal inoculation improved significantly leaf water potential, dry mass and P content. Drought stress increased significantly nitrate concentration in roots where the increase was much less in AM than non-AM. Drought stress decreased the concentration of soluble proteins in non-AM shoots, whereas non-significant decline occurred in AM shoots even under drought condition. The concentrations of ammonia and proline in drought stressed non-AM plants significantly increased, while mycorrhizal inoculation lowered significantly ammonia and proline accumulation. The decrease in leaf dry weight in drought stressed-plants was significantly correlated to the increase in ammonia (p<0.01) and proline concentration (p<0.01). These results suggested that the increased P content and N assimilation by mycorrhizal inoculation may be associated with drought stress tolerance, showing the moderating effects on shoot growth inhibition and ammonia accumulation in drought stressed-plants.

• Asian Journal of Turfgrass Science
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• v.19 no.2
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• pp.151-160
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• 2005

Research was initiated to investigate seasonal turf quality under a sand-based USGA soil system. USGA system 45 centimeters deep was built with rootzone layer, intermediate layer, and drainage layer. Six turfgrass entries were comprised of 3 blends and 3 mixtures from cool-season grasses (CSG). Turfgrass quality ratings were best in spring and fall, especially early May to early July and late August to early November. Kentucky bluegrass(KB) consistently produced the greatest quality, while perennial ryegrass (PR) the poorest. Intermediate turf quality between KB and PR was observed with tall fescue (TF). Among CSG mixtures it increased with KB but decreased with PR. There were considerable variations in summer turf performance. No summer drought injury was found in KB and TF. However, PR showed poor performance through summer as compared with other CSG. Results demonstrate that KB was the best and PR the worst among CSG grown in a sand-based USCA soil system.

• Weed & Turfgrass Science
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• v.2 no.3
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• pp.274-282
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• 2013

Research was initiated to investigate early germination and establishment characteristics of perennial ryegrass (PR, Lolium perenne L.). An alternative condition was applied in Experiment I with 8-hr light at $25^{\circ}C$ and 16-hr dark at $15^{\circ}C$ (ISTA condition). Experiment II was conducted under $5^{\circ}C$ to $25^{\circ}C$ (natural condition). Significant differences were observed in germination percentage, germination speed and germination peak time. Seed germinating vigor was 66.00 to 93.75% under ISTA and 66.25 to 93.50% under natural conditions. Germination speed, measured as days to germination of 50% through 90%, was much faster with 'Pennant II', 'Brightstar II', 'Sonata' and 'Accent II' under ISTA conditions. But it was faster only with 'Pennant II' and 'Brightstar II' under natural conditions. Germination peak time ranged 1.48 to 5.65 days under ISTA, while 2.17 to 10.63 days under natural conditions. Regardless of growing conditions, the shortest cultivars in peak time were 'Sonata', 'Pennant II', and 'Brightstar II' and the longest one 'Revenge GLX'. Considering germinating vigor, early germination speed and germination peak time, 'Pennant II', 'Brightstar II', 'Sonata' and 'Accent II' were regarded as excellent cultivars under ISTA conditions, while 'Pennant II' and 'Brightstar II' under natural conditions.

• Journal of The Korean Society of Grassland and Forage Science
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• v.29 no.4
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• pp.383-388
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• 2009

This study was conducted to investigate the dry matter intake, weight gain and the required area of grazing pasture for dairy goats. The experimental trials were conducted from April, 2007 to June, 2008 at the animal experimental station in Chungnam National University. The seed mixtures of grazing pasture were composed of orchardgrass (40%) + tall fescue (20%) + perennial ryegrass (10%) + alfalfa (15%) + red clover (15%). The grazing area was $5,000\;m^2$ which was composed of 4 paddocks (average $1,250\;m^2$/plot) and the goats were grazed twelve times by a rotational grazing system. The dairy goats (Saanen) were selected which had nearly the same body weight (average 31.1kg). The average chemical composition of herbage of mixture in grazing periods was crude protein (20.4%), NDF (65.3%) and ADF (31.1%) respectively and the in vitro dry matter digestibility was 68.9%. The average dry matter intake amount per head was 1.253 kg, and the intake amount per body weight was 3.01%. The average body weight gain during the grazing periods (184 days) was 17.4 kg, and the daily gain was 98 g. The required area of grazing pasture was calculated at $467.7\;m^2$ a dairy goat (weight 50 kg basis). This figure, being converted into animal unit (AU), corresponded to approximately 2.14 AU/ha.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.2
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• pp.137-144
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• 2004

The objective of this experiment was to suggest the optimum N fertilization level for turf type mixtures {Kentucky bluegrass(Newport) 40% + tall fescue(Rebell Jr.) 20%. + perennial ryegrass(Palmer II) 10% + redtop(Barricuda) 10% + red fescue(Salem) 10% + creeping bentgrass(Crenshaw) 10%}. The field trials were conducted from 1998 to 2000 at Chungnam National University in order to evaluate the dry matter yield and quality on the N levels(100, 150 and 200kg/ha). With increasing the N level, the average DM yields over 2-years of turf type mixtures significantly increased. The average total DM yields were obtained 6,551, 8,182 and 9,501kg/ha at N 100, 150 and 200kg/ha level(p<0.05), respectively. CP content and DMD were increased, whereas fibrous constituents was decreased(p<0.05), but CPDM and DDM yields were significantly increased with increasing the N levels over 2-year(p<0.05). Based on the results, considering the total DM yield and the quality of herbages which were incidentally produced from turf type mixtures, it can be suggested that the suitable N level was 200kg/ha. But increased N fertilizer usage for general purpose use and expenses on turf type mixtures should be considered in advance.

• Korean Journal of Agricultural Science
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• v.6 no.1
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• pp.15-20
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• 1979

In order to determine the effects of different degrees of moisture stress on germination of various plant species, hundred seeds of six vegetables and six turfgrasses were germinated in petri dishes on filter papers moistened with water-mannitol solutions of 0, 2, 4, 8, 10, and 12 atmosphere osmotic concentration (degrees of moisture stress). The percentages and rates of germination of all species tested were generally decreased with: increase in moisture stress. Chinese cabbage and cucumber were quite resistant to physiological drought as the germination was not appreciably affected until moisture stress exceeded 10 atmosphere. However, increase in moisture stress decreased germination affecting most seriously tomato, carrot and squash. Weeping lovegrass, Italian ryegrass and perennial ryegrass germinated well at 10 atmosphere but the germination of Kentucky bluegrass, meadow fescue and orchardgrass was greatly reduced by increasing osmotic pressure. The result indicates that it may be possible to select drought resistant species and varieties by their ability to germinate in osmotic solutions.

• Journal of The Korean Society of Grassland and Forage Science
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• v.9 no.2
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• pp.62-67
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• 1989

A breeding program in progress at Suweon Livestock Experiment Station, RDA, involves the hybridization of italian ryegrass (Lm) and several leading forage grasses in an effort to combine the nutritive, productivity and palatability qualities of Lm with the adaptive and cold resistance qual; .les of several leading grasses. In order to study the fate of the hybridization between remotely related species, immatured hybrid embryos were cultured on media. The emasculated plants of Lm were Sikem and Tetrone. Reweille, 2n=14, of perennial ryegrass (Lp.), Forager, 2n=42, of tall fescue(Fa), First, 2n=14,of meadow fescue(Fp), Potomac, 2n=28, of orchardgrass(Dg), and Richmond, 2n=42, of timothy(Ph.p) were used as pollinators. Embryos were isolated on 4, 8, 12, 16, and 20 days after pollination and cultured them on modified Murashige and Skoog media. Calluses and plantlets have been obtained after 8 days old embryos crossing between $Lm{\times}Fa$, after 12 days embryos crossing between $Lm{\times}Lp$, Dg, and Ph.p, and after 16 days embryos crossing between $Lm{\times}Fp$. Both callus and shoot formation occurred on 6 % or less of the plated embryos of $Lm{\times}Fp$, Dg, and Ph.p. Embryoderived callus forming shoots have been obtained from 4 days old embryo crossing between $Lm{\times}Dg$ which has not successfully been done anywhere as far as we know. It means that hybrid plants of species without crossability can be obtained through the use of immatured embryo culture. Some of plated embryos developed directly shoots from embryos and the others shoot-forming callus. Cross between related species showed a high frequency of directly shoot formation from plated embryos and cross between remotely related species a high frequency of callus formation.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.2
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• pp.90-96
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• 1991

This experiment was carried out in order to estimate the recovery days of root and stubble to the days after cutting, and contribution of specific stubble weight on the regrowth was examined using the relationships between the dry weight of shoot and yield components, and regrowth parameters by the days after cutting. The varieties examined were Maprima, Manhattan, Tove, Peramo, Caliente, Tempo and P-2 grown under individual plant basis. The results are may be summarized as follows: 1. Dry weight of root and stubble were recovered up to 13.5 and 11 days after cutting, respectively. 2. Dry weight of shoot(regrowth parts+stubble) was affected significantly by the varieties, stages of regrowth and variety x stage of regrowth. 3. The variety with tiller weight type showed higher average productivity of shoot than those of the variety with tiller number type. 4. Absolute growth rate(AGR) of shoot was correlated significantly with regrowth parts, stubble, root and weight of a tiller at the early stage of regrowth(up to 12 days after cutting), and correlated with regrowth parts, stubble, weight of tiller and stubble area at the late stage of regrowth(up to 20 days after cutting). 5. Contribution of specific stubble weight to absolute growth rate of shoot was different between the stages of regrowth. Thus, regrowth parts per specific stubble weight(RP1SSbW) and weight of tiller per specific stubble weight(WT1SSbW) contributed to absolute growth rate of shoot at the early stage of regrowth, and efficiency of specific stubble weight(ESSbW), regrowth parts per specific stubble weight (RPISSbW) and weight of a tiller per specific stubble weight(WT1SSbW) contributed to absolute growth rate of shoot at the late stage of regrowth. 6. Regrowth utilization rate(RUR) was one of the useful regrowth parameter to indicate the regrowth potential of grasses.

• Korean Journal of Weed Science
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• v.12 no.3
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• pp.230-260
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• 1992

The paper was reviewed the research results on weed dynamics and effective control methods in direct-seeded rice crop. Direct seeding method resulted in drastic increment of weed growth compared to transplanting method and also changed in troublesome weed flora. Two to three fold more weeds were harvested at the direct seeded rice and weed flora of dominant species shifted toward $C_4$type grass weeds. Some of the important troublesome weeds in direct seeded rice were Echinochloa crus-galle, Oryza saliva ssp spontanea, Leptochloa chinensis. Setaria viridus. Digitaria adsendens, Sesbania exaltata, Aeschynomene indica, Algae, etc. Yield loss due to weed competiton was about 40-60% for water-seeded and about 70-100% for dry-seeded rice while these for transplanted rice were about 25-35% for mechanical transplanting and about 10-20% for manual transplanting, respectively. Integrated weed management concept was neede to approach weed control effectively. Several cultural technologies were very effective to suppress the weed growth. These were tillage operation, water management, seeding date and seeding rate. Crop residues of barley, rice, wheat, oat and italian ryegrass were also effectivly suppressed the paddy weeds particularly to Potamogeton distiuctus, a perennial broadleaf weed. A pathogen of Epicoccosorus nematosporus identified from Eleocharis kuroguwai was an excellent potential bioagent to control the most troublesome perennial sedge weed of E. Kuroguwai without arising any detrimental effect. The herbicidal efficacy of this pathogen was as high as bentazon herbicide. Plant growth regulator of paclobutrazol (pp-333) was another possible alternative to reduce the herbicide use. In current, herbicide exhibited the most conspicuous results to control weeds in direct-seeded rice even though the application technologies were not fully established. Recommendations for herbicide application were suggested for in both water-and dry-seeded rice in USA, Japan and Korea, respectively. To make better and comprehensive recommendations further studies on weed ecology and herbicide development were emphasized.

• Asian Journal of Turfgrass Science
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• v.13 no.1
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• pp.37-54
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• 1999

This study was initiated to evaluate the seasonal turf performance in a tree shade and to suggest shade-tolerant turfgrasses suitable for domestic climate conditions. Atotal of 21 trufgrasses were tested, comprising of Korean lawngrass, shade-tolerant fine fescues, and newly-developed, shade-tolerant varieties of cool-season grasses. Dirrerences in shade tolerance were observed among varieties, species, and genera. Overall turf performance of C3 turfgrasses was better than that of C4 Korean lawngrass under a tree shade. Coarse-type fescues were excellent in shade tolerance, bluegrasses good, ryegrasses medium, fine-type fescues fair, and zoysiagrasses poor, respectively. Inter-species comparison in relative index of shade tolerance(IRST) demonstrated that tall fescue and fough bluegrass were greatest of 7.3, Poa supina 6.4, perennial ryegrass 5.0, Kentucky bluegrass 4.8, and fine fescues least, respectively. A great variation in RIST was observed with fine fescues; creeping red fescue was 3.6, chewings fescue 2.5, hard fescue 2.1, and sheep fescue 1.4, respectively. Among 21 turfgrasses evaluated, tall fescue 'Rebel Jr.', 'Era', and 'Oixie' and rough bluegrass 'Sabre' were the shade-tolerant varieties under a tree shade in Korea. Tall fescue, 'Rebel Jr.' was considered as the most shade-tolerant variety in the experiment. Fine fescues as creeping red fescue, chewings fescue, hare fescue, and sheep fescue, used as the shade-tolerant species in a cool climate of Europe and North America, were not suitable under domestic climate conditions.