• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.190-194
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• 2011

Potassium (K) is one of the essential nutrients for plants but is not a constituent of any plant compound. K is substances for activation of many enzymes and influences the process that the enzymes are involved in catalyzing. Although experimental results associated with the K effects with both benefits and no effects on turfgrass growth were reported, the limited research results of K effects on turfgrass among K sources are available in Korea. The objectives of the study was conducted to evaluate responses of Kentucky bluegrass (Poa pratensis L.) treated by fertilizer treatments with six K sources. There were six fertilizer treatments as K sources applied to Kentucky bluegrass which were potassium nitrate (13-0-44, PN), potassium chloride (0-0-60, PC), potassium sulfate (0-0-50, PS), polymer-coated potassium sulfate (0-0-45, PPS), potassium thiosulfate (0-0-25, PT), and potassium sulfate granulated with methylene urea (20-0-25, PSU). Potassium of $8g\;m^{-2}$ and N of $5g\;m^{-2}$ was applied 4 times giving a total 20 and $30g\;m^{-2}$, respectively. Although significant differences were found for turfgrass color, quality, chlorophyll index, and clipping dry weight, no consistent results among K sources were found during the one year study. Overall, K treatments didn't affect turfgrass growth in this study.

• Weed & Turfgrass Science
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• v.7 no.2
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• pp.148-157
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• 2018

Research was initiated to evaluate four domestic and overseas organic soil amendments (SAs) on turfgrass groundcover and density and to provide basic information on practical sports turf establishment. This study was conducted in Agrostis palustris Huds. (CB) grown in sand-based root zone. A total of 20 treatments of SA+sand were prepared by mixing 10 to 50% (v/v). These amendments were SABP (Berger Peat), SAEP (Eco-Peat), SAGS (G1-Soil), and SAPP (Premier Peat). Turfgrass groundcover and density significantly varied with SAs, its mixing rate to sand and week after seeding (WAS). Cumulative turfgrass density was variable, but a great change occurred between 2 and 4 WAS. Turfgrass density at 2 WAS ranged from 36.7 (SABP 30) to 89.7% (SAGS 20), being 53.0% in differences among treatments. However, CB reached to carrying capacity around 6 WAS. Thus, most treatments were similar to 90% or so in density. At the end of study, overall groundcover ranged between 60.7 (SAEP 10) and 96.7% (SAPP 50). Proper mixing rate was variable with SAs, being 10 and 20% for SABP and SAGS, respectively. But the optimum rate was 50% for both SAEP and SAPP.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.08a
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• pp.162-163
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• 2005

• Asian Journal of Turfgrass Science
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• v.11 no.2
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• pp.139-143
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• 1997

A major purpose of a scientific meeting is the exchange of information. Traditionally, authors have preferred to present their research in an oral format. However, poster presentations are becoming more popular every year. Today, poster and oral presentation are recognized as being of equal status, Regardless of which format you select, remember that the poster or oral presentation must he carefully planned, clear and concise, oriented to transfer information effectively, and hold the attention of the learner.

• Asian Journal of Turfgrass Science
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• v.22 no.1
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• pp.25-34
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• 2008

This study was conducted to determine the optimum dose ranges for a mutation breeding based on the observations of a seed germination and an early growth in turfgrasses. Three warm season (Zoysiagrass, Bermudagrass, and Seashore paspalum) and four cool season turfgrasses (Kentucky bluegrass, Tall fescue, Perennial ryegrass, and Creeping bentgrass) were used in this study. We investigated the percentage of a seed germination and a seedling growth after irradiating the turfgrass seeds with various doses of gamma-ray (50, 100, 150, 200, 250, 300, 400, and 500 Gy). After 24 h with a gamma irradiation, the seeds were sown on the wet filter paper in a petri dish and maintained for 3 weeks at 30$^{\circ}C$ for the warm season turfgrasses and at 25$^{\circ}C$ for the cool season turfgrasses. Data on a seed germination and a seedling growth with three replications were collected. The percentage of seed germination was decreased with an increase of the gamma-ray dose. Shoot and root growth, and the fresh weight were decreased significantly as the radiation dose was increased. A radiation dose indicating a 50% growth inhibition ($LD_{50}$) with a gamma irradiation was varied among those turfgrass species used, with the highest at about 500 Gy for bermudagrass and the lowest at 100Gy for tall fescue. The optimum dose for a gamma irradiation for a selection of turfgrass mutants was considered to be about 300, 150, 500, 150, 200, 100 and 200 Gy for zoysiagrass, seashore paspalum, bermudagrass, Kentucky bluegrass, perennial ryegrass, tall fescue, and creeping bentgrass, respectively.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.11-16
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• 2011

This study was conducted to identify the morphological characteristics and variations level by site environment of native bermudagrass (Cynodon spp.) from costal and island region in South Korea. Soil chemical properties and morphological characteristics were investigated. There were significant differences in plant height, leaf width, leaf length, cotton on leaf blade, stolon, and number of seed per spike depending on where they were collected from natural habitat. We have discovered a variety of variation among the investigated traits in Korean native bermudagrass ecotypes. There were broad leaf and fine leaf types of native bermudgarass in S. Korea. Adaptability was in very high on inadequate environment in bermudagrass with broad leaf types, it has also been suggested that management worth in terms of use. These results may provide basic information for bermudagrass breeding development and the collected types during this investigation would be worth being preserved as genetic resources for further breeding purposes.

• Asian Journal of Turfgrass Science
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• v.26 no.2
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• pp.123-128
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• 2012

Kentucky bluegrass (Poa pratensis) is most widely used in golf courses and athletic fields. Weakness of Kentucky bluegrass is shallow root zone and has weak tolerance to shade. One of the biggest disadvantages is high demand of water. Water content is important factor to maintain excellent color and quality of turfgrass. There are two irrigation methods which are 'deep and infrequent (DI)' and 'Light and frequent (LI)'. The objective of the study is to investigate Kentucky bluegrass growth treated by different irrigation frequency. Three irrigation frequency were made; no irrigation, every other day, and weekly. The same amount of water was used between every other day and weekly irrigation except no irrigation. No irrigation mean no artificial water supply and precipitation only. No irrigation treatment produced turfgrass quality lower than acceptable rating of six in July and August. Under the weather condition of 2011, no irrigation could not maintained acceptable turfgrass quality. No significant differences were found for Kentucky bluegrass quality between DI and LI.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.213-221
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• 2006

This study was designed to determine what sensor-based technologies might reliably and accurately predict irrigation scheduling needs of warm-season turfgrass. 'Floratam' St. Augustinegrass[Stenotaphrum secundatum(Walt.) Kuntze] and 'Sea Isle I' seashore paspalum(Paspalum vaginatum Swartz) were established in tubs in the Envirotron Turfgrass Research Laboratory in Gainesville, FL in the spring of 2002. Each grass was subjected to repeated dry-down cycles where irrigation was withheld. Sensor-based data were collected and these evaluations were used to determine if irrigation scheduling could be determined based on plant response during dry-down. Results indicated that reflectance indices($P{\le}0.001$) and soil moisture($P{\le}0.0001$) throughout the dry-down cycle can predict the need for irrigation scheduling as turf quality declined below acceptable levels.

• Asian Journal of Turfgrass Science
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• v.26 no.2
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• pp.135-139
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• 2012

Creeping bentgrass (Agrostis stolonifera) is one of the most popular turfgrasses for high-quality playing surface such as putting green on golf courses and athletic fields. Continues damage such as divot injury on creeping bentgrass is major issue to maintain golf course properly. Although plentiful researches to maximize divot resistance have been reported, minimal research has focused on relation between nitrogen (N) sources and divot resistance. The study was conducted to determine the effect of N source for turfgrass divot recovery and overall tee performance. Eleven fertilizer treatments as N sources were applied to creeping bentgrass 'Penncross'. Before the first application, divot injuries were simulated by removing a core of soil and turfgrass from established plots and backfilling with native soil. Data collection included turfgrass color and quality. N release speed did not influenced divot recovery. Frequency of urea application had no effects on divot recovery. Urea with split application had no difference with no treatment for divot recovery. Polyon product especially polyon mini (41-0-0) had the best performance for divot recovery and for maintaining better turfgrass quality. Overall, small particle size of slow-release N form would influence creeping bentgrasss to recover divot damage.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.348-359
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• 2015

Total 443 isolates of actinomycetes were isolated from turfgrass rhizosphere as potential biological control agents. The two isolates (S11 and S4) showed highest cellulase activity with compared to the other isolates that exhibited a clear zone of 1.2 mm around the colony on cellulose agar medium. S12 strain appeared the most active chitin degrading, which exhibited a 1.2 mm of clear zone. The highest proteolytic activity on skim milk agar was which exhibited a 7.5 mm of clear zone by S2 strain. S1 strain from the soli showed siderophore production ability, which exhibited a 0.6 mm of large clear zone on chrome azurol S agar. The antifungal activity of the volatile compound producing by 4 selected actinomycetes was investigated that inhibition rate against Rhizoctonia solani AG2-2 and Sclerotinia homoeocarpa. Growth inhibition effect of S8 isolate against S. homoeocarpa was appeared to 94.8%, S2 to 76.9%, S5 to 46.1% and S12 to 43.5%. The significant inhibition effects on mycelial growth of S. homoeocarpa were shown on media with four strains. The inhibition effect was the highest with S8 strain treatment at 94.8%.