• Asian Journal of Turfgrass Science
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• v.5 no.1
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• pp.1-10
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• 1991

The purpose of the experiment was to determine the effect of nitrogen sources (urea, ammonium sulphate, ammonium nitrate) and potassium sources (potassium chloride, potassium sulphate) on the growth and quality of Zoysia japonica Steud. This experiment was conducted at Seoul City University turf field from 1988 to 1989. The results of this experiment were summarized as follows; 1. Urea and Ammonium sulphate resulted in superior clipping yield compared to ammonium nitrate. The growth of rhizome and stolon increased significantly with urea forms, but ammonium sulphate treated plots exhibited the highest the growth rate of root. 2. Ammonium sulphate showed best turf color rating while ammonium nitrate resulted in the poorest. Prolongation of the green period showed longer in ammonium sulphate and urea treated plots than ammoium nitrate. 3. Urea and ammonium sulphate exhibited superior visible quality and shoot density compared to ammonium nitrate. 4. The uptake of mineral nutrient showed the highest concentration with urea plots. Surface soil pH was allowed to become slightly acid with the ammonium sulphate and potassium sulphate treatments, while the application of N and K sources did not cause significant differences in mineral element content in soil.

• Asian Journal of Turfgrass Science
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• v.22 no.1
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• pp.65-74
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• 2008

Traffic management is becoming an important issue in turfgrass practise on golf course. The objective of this study was to investigate the combined impact of different traffic times and types of fertilization. Traffic treatment was applied in morning (AM), noon, and afternoon (PM). Fertilizers used include faster-release fertilizer (21-17-17) and slow-release fertilizers (12-6-18, 11-3-22, 20-3-20, 10-3-10). Experiment was conducted from Oct. 1 to Nov. 30, 2005 on a nursery putting green of Incheon Grand Golf Club. The growth and quality of creeping bentgrass (Agrostis polustris cv. 'Seaside II') were evaluated on visual leaf color, leaf texture, shoot density, and root length. The measurement at 20 days after treatment, turfgrass color and leaf texture showed the best result on 10-15-10 + Noon-traffic plot. Turf quality and traffic tolerance were not different at Am and Pm traffic treatment. However, traffic stress in early morning and late evening caused the most severe damage to the turfgrass. Shoot density was the highest in 10-15-10 + Noon-traffic treatment but root length was not different among treatments after 30 day measurement. Among the fertilizers, slow release fertilizer resulted in higher turf quality and traffic tolerance than fast release fertilizer, however, shoot density did not showed a significantly different. For the fast recuperation of turfgrass from traffic injury in the early winter, it is recommended to avoid early morning and late evening traffic such as cup replacement and other maintenance practise. It is also recommended to delay the first tee-up time and ending early for last tee time during cold weather season.

• Weed & Turfgrass Science
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• v.4 no.3
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• pp.249-255
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• 2015

Trichoderma spp. were famous fungi used for turfgrass management in golf course. This study was conducted to evaluate effects of two microbial fertilizers containing Trichoderma harzianum and T. atroviride on the growth and quality of creeping bentgrass with turf color index, chlorophyll index, root length, shoot number, clipping yield and nutrient content. Treatments were designed as follow; non-fertilizer (NF), control fertilizer (CF), T. harzianum (TH), and T. atroviride (TA). Chlorophyll index and root length of TH and TA were increased than these of CF and shoot number and content and uptake of nitrogen (N) of TA higher than these of CF. The N content in turfgrass tissue was significantly related to shoot number, root length and N uptake (P<0.05) and shoot number was positively relate to chlorophyll index (P<0.05). These results indicated that application of Trichoderma harzianum and T. atroviride improved a growth and quality of creeping bentgrass by promoting N uptake.

• Asian Journal of Turfgrass Science
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• v.22 no.2
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• pp.133-140
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• 2008

The growth of root and shoot normally decline dramatically in mid-summer of Korea, moreover the cool-season turfgrassgrass eventually wither to death over $30^{\circ}C$. The increase of air temperature also drives the heat of soil, that makes stress on root system. The heat stress affects physiological mechanisms of hormonal unbalance that stimulates shoot growth, photosynthesis, and transpiration. To solve those problems, many studies have been carried out to control soil moisture and OM content to decrease soil temperature for dissolving the growth retardant by heat stress. This study initiated to analyze the change of soil temperature with soil moisture, and the effect of soil depth and moisture content on heat transmit and thermal changes on turfgrass growth(productivity, green color, and damage by dryness and high temperature). Kentucky bluegrass plots prepared with 25%, 33%, 40% soil moisture treatments. Soil temperature was measured every five min. with four thermo-sensors at 12 and 2 cm soil depth. The most acceptable growth showed at 33% soil moisture, but the worst result showed at 40%. The soil moisture seriously affected on the growth of Kentucky bluegrass, however the quality of turfgrass may acceptable if we can control soil moisture down to 33% when the flooding season of monsoon.

• Horticultural Science & Technology
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• v.30 no.6
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• pp.635-641
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• 2012

In Korea, slurry composted and biofiltered (SCB) liquid fertilizer is produced through the composting and biofiltering of animal waste. An appropriate guidelines involving proper treatment of SCB liquid fertilizer on turfgrass should be considered. An experiment was conducted to determine the optimum application amount, timing, and frequency of SCB liquid fertilizer for Zoysia japonica 'Millock'. The SCB liquid fertilizer was applied in low, medium, and high amount (N at 15, 25, and 40 $g{\cdot}m^{-2}$ per year in 2010, and 10, 20, and 40 $g{\cdot}m^{-2}$ per year in 2011, respectively) and treated during the growing season or dormancy period. During the growing season, SCB liquid fertilizer was applied twice or four times. The greatest improvement in turf quality for both years was in SCB plots applied four times with N at 40 $g{\cdot}m^{-2}$ per year during the growing season (SH4). This treatment exhibited turf color retention in the fall, and enhanced clipping yield during the growing and fall seasons. SCB plots with four times during the growing season (SL4, SM4, and SH4) exhibited higher shoot density relative to the same amount of other SCB treatments. Plots treated during the dormancy period also showed a high turf color index during the next growing season in 2011. The results indicate that SCB with high amount up to N at 40 $g{\cdot}m^{-2}$ per year applied four times during the growing season and dormant application produced high turf quality and growth, and could be recommended as an optimum application guide.

• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.88-96
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• 2010

Zoysiagrass, especially Jungji implicating medium-leaf type zoysiagrass has been widely used in South Korea recently. This study was carried out to classify 36 selected medium-leaf type zoysiagrass accessions compared to 5 basic zoysiagrass species using RAPDs. Morphological characteristics such as leaf width, leaf angle, leaf sheath length, existance of trichomes and stolon color were measured as useful characteristics for identification of species in Zoysia genus. Nineteen RAPD markers were identified using 8 selected random primers. The dissimilarity coefficient of variants ranged from 0 to 0.736. Three zoysiagrass groups were clustered by dissimilarity coefficient analysis. Group 1 consisted of Z. japonica and some US varieties including 'Zenith' and 'Meyer'. Group 2 consisted of Z. sinica, Z. macrostachya and Korean commercial varieties such as 'Anyang', 'Samdeock', and 'Pyeongdong' medium-leaf type grasses. Group 3 was genetically distinct from Group 1 and Group 2, and included Z. matrella and Z. tenuifolia. 'Anyang', 'Samdeock', and 'Pyeongdong' medium-leaf type zoysiagrasses showed very close genetic relationship with Z. sinica and Z. macrostachya.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.69-72
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• 2011

Soil aggregate is a vigorous procedure including soil physical, chemical, and biological processes. Pore space created by binding these particles together improves retention and exchange of air and water. Various researches have reported that the benefits of organic polymers that may increase aggregate stability. The purpose of the study was to determine if a liquid organic polymer mixture has any influence on perennial ryegrass quality or soil aggregation. $Turf2Max^{(R)}$ was applied to two soils as a source of liquid organic polymer. Fine-loamy soil from local Iowa topsoil with 4.0% organic matter was screened and dried. Commercial baseball infield clay, $QuickDry^{(R)}$, was used as the second soil There were three rates of liquid organic polymer (0, 2, and 4%). there was no visual improvement in turf grass color, quality, or growth by using organic polymer. It is possible that aggregate stability increases with use of organic polymer. The aggregate stability study needs to be repeated in the greenhouse and then substantiated under field conditions for these preliminary observations.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.3
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• pp.1-12
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• 2000

식물생장조절제(Plant Growth Regulators, PGRs)를 이용한 예초관리 방법이 들잔디 엽색 및 품 질에 미치는 영향을 규명함으로 잔디 적응력 관점에서 적합한 PGR 종류 및 살포수준을 파 악하고자 본 연구를 시작하였다. 실험은 들잔디 생육이 왕성한 시기인 6월(실험 I)과 7월(실험 II) 2회에 걸쳐 각각 다른 장소에서 실시하였다. 공시약제 처리구는 Type I PGR인 amidochlor 3 수준 및 mefluidide 3 수준 과 Type II PGR인 trinexapacethyl 4 수준, 그리고 무처리구를 포함하여 전체 11 처리구였 고, 실험구 배 치는 난괴법 4 반복으로 하였다. 공시한 3종류 PGR 모두 잔디엽색 및 품질에 통계적으로 유의한 차이 가 있었지만, PGR 종류.살포수준 및 생육 상태에 따라 처리효과는 다르게 나타났다. 잔디 엽색 및 품질 은 PGR 살포후 경과기간에 따라 점진적으로 억제되는 경향이었다. 처리 1주후 잔디품질은 대조구에 비 해 큰 차이가 없었지만, 2주에서 4주까지는 PGR 종류 및 살포수준에 따라 유의하게 감소하 여 0.08 ml/ $m^2$ 이상의 trinexapac-ethyl 처리구 및 1.20 ml/$m^2$ 이상의 mefluidide 처리구에서는 가장 크 게 나타났다. 처리 4주부터 대부분 처리구에서 잔디품질이 적정수준 이상으로 회복되기 시작하였다. 본 실험을 통해 잔디관리 수준에서 저관리 잔디지역은 0.08 ml/$m^2$ 수준의 trinexapac-ethyl 처리구가 장기간 생장억제 관점에서 실용성과 경제성 측면에서 들잔디 관리에 효율적인 것으로 판단되었고, 고관리 잔 디지역은 0.04~0.08ml/$m^2$ 수준의 trinexapac-ethyl 처리구 및 0.60~1.20 ml/$m^2$ 수준의 amidochlor 처 리구가 적합 한 것으로 판단되었지만, 계절에 따라 PGR 효과정도가 다르게 나타났다. 따라서, 잔디 관리 시 잔디의 생육상태, 예초 절감 기간, 잔디품질의 기대수준 및 적용할 수 있는 관리수준에 따라 적합한 PGR 종류 선정과 함께 살포시기 및 살포량을 효율적으로 결정하는 것이 필요한 것으로 사료되었다.

• Weed & Turfgrass Science
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• v.2 no.2
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• pp.198-201
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• 2013

This study was carried out to develope new zoysiagrass cultivar Semil' (Registration no. 1749). Artificial crossing between the collected lines of typical Z. matrella, NM1 (collected in South Korea) and the different ecotype of Z. matrella, ASm (collected in South Korea) was made to develop a F1 hybrid plant (NM1 ${\times}$ ASm). Among the 30 progenies, (NM1 ${\times}$ ASm)-1 (Semil) showed superior performance in density rating. 'Semil' showed genetically light green color, with narrow leaf width ($2.7{\pm}0.12mm$), and low plant height ($10.3{\pm}3.7cm$), Length to lowest leaf blade of this cultivar was $1.8{\pm}0.15cm$, which may allow low mowing height upto 12 mm.

• Korean Journal of Weed Science
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• v.17 no.3
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• pp.303-309
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• 1997

Variation of morphological and physiological traits of 50 Bidens tripartita accessions were studied and the accessions were grouped through cluster analysis based on four major characters; plant type, leaf partition, achene length, days to flowering. Bidens tripartite accessions have shown significant variations in plant type, stem length, days to flowering, leaf shape, leaf partition, chlorophyll content, leaf color, stem color, achene color, achene length and achene shape. Most of Bidens tripartite accessions appeared to have strong dormancy and also photodormancy with some exceptions. Plants could be classified into 5 types from straight(I) to triangle(V), and intermediate diamond type(III) was prevalent. The plant type score has negative correlation with the stem length. None, three, and five part leaved plants were observed and most of them were three or five parted. Leaf partition had negative correlation with achene length and chlorophyll content. Average days to flowering was 108 days in the range of 94~141 days. It had positive correlation with achene length and leaf shape and negative correlation with achene color. Average achene length was 10.0mm and it had positive correlation with achene shape, stem length, days to flowering and leaf shape. It also had negative correlation with leaf color, stem color, achene color, leaf partition. Bidens tripartite accessions could be divided into identifiable six groups from the cluster analysis at the distance 0.06 using Ward's minimum-variance method.