• Asian Journal of Turfgrass Science
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• v.21 no.2
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• pp.155-161
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• 2007

This study was initiated to evaluate the growth characteristics of creeping bentgrass cultivars during the sprlng season. The green-up of 'CY' and 'T-1' were about 2 weeks earlier than the other cultivars followed by 'Penn A' 'Crenshaw', 'L> 'Penncross' > 'Putter' > 'Dominant' > 'SR1020' in that order. 'T-1' and 'CY-2' had the highest chlorophyll content while 'Penncross' had the lowest during the spring. 'Crenshaw' and 'Penn A-4' showed the highest shoot density in this research, followed by 'CY-2', 'L-93', 'T-1', 'Putter', 'Dominant', 'SR1020', and 'Penncross' in that order. In case of root length, 'CY-2' and 'L-93' were the best cultivars, but 'Penncross' was worst during the spring. 'CY-2' had the best visual quality among the cultivars, 'T-1' and 'Crenshaw' also classified as high visual quality group whereas 'SR1020', 'Dominant' and 'Penncross' were grouped in relatively low quality. In conclusion, 'CY-2', 'T-1' and 'Crenshaw' were the best cultivars in terms of growth characteristics in spring. Conversely, 'SR1020' and 'Penncross' were the poorest cultivars. These results can be more useful for management or constructing of golf courses. However, this research was performed with little compaction stress. More information is needed on the tolerance to compaction stress of these bentgrass cultivars.

• Weed & Turfgrass Science
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• v.6 no.4
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• pp.313-321
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• 2017

Wetting agent is designed to reduce the surface tension of the liquid and spread more easily across or penetrate into the soil against water repellency. The effect of wetting agent to seed germination is not clear. Using germination enhancer is one of the methods to increase the germination speed of turfgrass seeds and to shorten establishment period. The objective of the study was to evaluate germination enhancer and wetting agent for quick establishment of various Kentucky bluegrass cultivars. The germination enhancer was used at two levels of 0.3 and $0.6ml\;kg^{-1}$ as low and high, respectively. Two levels of wetting agent were of 0.46, and $0.92ml\;m^{-2}$ as low and high, respectively. Germination enhancer has no synergistic effect with wetting agent. When quick establishment is required, selection of cultivar would be more effective instead of using germination enhancer and wetting agent. Among Kentucky bluegrass cultivars, 'Award' had the greatest turfgrass coverage for establishment and the greatest turfgrass color and quality based on the result of the study. When quick establishment is required, selection of cultivar would be more effective instead of using germination enhancer and wetting agent.

• Asian Journal of Turfgrass Science
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• v.11 no.1
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• pp.73-85
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• 1997

Although zoysia grass (Zoysia spp.) has a lot of excellent chracteristics as warm-season grass, it have been limited in use due to slow establishment, low seed production, poor shade tolerance and other factors. Breeding trials have been continued from 1900's, much attentions have been paid especially in U.S.A., Korea and Japan recently. In U.S.A., more than 24 varieties had been evaluated at National Turfgrass Evaluation Program(NTEP) from 1991 to 1995 and some were regsistered as commercial. After the 6th International Turfgrass Research Conference at Japan in 1989, Japan Turfgrass In-corporation (JTI) sponsored by private companies and government carried out breeding programs for pest, salt, and shade tolerant and herbicide resistant varieties. JTI also has been trying to im-prove vigor and breed evergreen zoysia Korean breeders collected germplasms since 1960's. After USDA breeders came to Korean penesula in 1982, Korean breeders joined with USDA zoysia breeding project for several years. Many interspecific hybrids and natural selected varieties were breeded that period both in U.S.A and Korea. Breeding objectives were to extend green color period, improve leaf quality and density, and better leaf color at dormant stage. Since 1990's, zoysia grass breeding trials are getting more diverse in many points such as random amplified polymorphic DNA (RAPD) assay for ecotype identification. The objectives of this study are to evaluate germplasms in Korea, and also review the present status and future prospect in zoysia grass breeding in the world.

• Asian Journal of Turfgrass Science
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• v.23 no.1
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• pp.9-22
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• 2009

Due to increasing concerns over issues with both water quantity and quality for turfgrass use, research was conducted to determine the response of five warm-season turfgrasses to deficit irrigation and to gain a better understanding of relative drought tolerance. St. Augustinegrass(Stenotaphrum secundatum [Walt.] Kuntze.) cultivars 'Floratam' and 'Palmetto', 'SeaIsle 1' seashore Paspalum(Paspalum vaginatumSwartz.), 'Empire' zoysiagrass(Zoysia japonica Steud.), and 'Pensacola' bahiagrass(Paspalum notatum Flugge) were established in lysimeters in the University of Florida Envirotron greenhouse facility in Gainesville. Irrigation was applied at100%, 80%, 60%, or 40% of evapotranspiration(ET). Evaluations included: a) shoot quality, leaf rolling, leaf firing; b) leaf relative water content(RWC), soil moisture content, chlorophyll content index(CCI), canopy photosynthesis(PS); c) multispectral reflectance(MSR); d) root distribution; and e) water use efficiency. Grasses irrigated at 100% and 80% of ET had no differences in visual quality, leaf rolling, leaf firing, RWC, CCI, and PS. Grasses irrigated at 60% of ET had higher values in physiological aspects than grasses irrigated at 40% of ET. 'Sealsle 1' and 'Palmetto' had a deeper root system than 'Empire' and 'Pensacola', while 'Floratam' had the least amount of root mass. Photosynthesis was positively correlated with visual assessments such as turf quality, leaf rolling, leaf firing, and sensor-based measurements such as CCI, soil moisture, and MSR. Reducing the amount of applied water by 20% did not reduce turfgrass quality and maintained acceptable physiological functioning.

• Korean Journal of Environmental Agriculture
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• v.41 no.3
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• pp.167-176
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• 2022

BACKGROUND: Nitrogen (N) is an important element for turfgrass (Zoysia matrella) growth; however, standard N application rate for turfgrass is not established yet. This study was conducted to evaluate the effect of N application rates on the growth and quality of turfgrass for establishment of standard N application rate. METHODS AND RESULTS: Treatments were as follows; control (0 N g/m²/month), 1N (1 N g/m²/month), 2N(2 N g/m²/month), 3N (3 N g/m²/month), 4N (4 N g/m²/month), and 5N (5 N g/m²/month). N application improved visual turfgrass quality. Compared with the control, clipping yield of all N treatments increased by 90~194%. The grass shoot weight of 3N, 4N, and 5N treatments increased by 52%, 43%, and 111%, respectively, and the stolon weight of 4N and 5N treatments increased by 412% and 201%, respectively, compared to the control. The N uptake amount and N recovery rate were estimated to be 4.10~6.28 g/m² and 14~58%, respectively. CONCLUSION(S): These results indicate that considering visual quality, clipping yield, N uptake amount, and N recovery, the application rate of 2~3 N g/m²/month was suggested to be suitable for Z. matrella production.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.286-296
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• 2023

This study was conducted to evaluate the effects of soil microbial fertilizer (SMF) containing Saccharomyces cerevisiae HS-1 and Streptococcus thermophiles HS-2 on the growth of creeping bentgrass. For the pot experiment, the treatments were as follows: no fertilizer (NF), control (3 N g/m²/month), SMF-1 (control+SMF 2 mL/m²/time), and SMF-2 (control+SMF 4 mL/m²/time). For the plot experiment, the treatments were as follows: NF, control, SMFp-1 (control+SMF 1 mL/m²/time), SMFp-2 (control+SMF 2 mL/m²/time), and SMFp-3 (control+SMF 4 mL/m²/time). In the pot experiment, visual turfgrass quality and the uptake amount of nitrogen (N) and potassium (K) were increased under the SMF treatments, whereas the content of chlorophyll (a, b, and a+b) and clipping yield were not considerably different compared with the control. In the pot experiment, the amount of SMF positively correlated with visual turfgrass quality and uptake amount of N and K. In the plot experiment, turfgrass density was increased by 12.9-19.2% under SMFp treatments compared with the control. These results indicated that the application of SMF containing Sa. cerevisiae HS-1 and St. thermophiles HS-2 improved the quality, density, and growth of creeping bentgrass via prompting the uptake of N and K.

• 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.

• Asian Journal of Turfgrass Science
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• v.23 no.2
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• pp.345-352
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• 2009

Zoysiagrass (Zoysia japonica Steud) is a warm season turfgrass species widely used for sports field and golf courses. Many cultivars are propagated through vegetative methods. This study was conducted to develop an optimum culture medium and culture conditions for embryogenic callus induction and plant regeneration, and to establish a cell suspension culture system for use in zoysiagrass breeding and propagation. The results indicated that adding $Cu^{++}$ at 2.5 mg $L^{-1}$ to the induction medium was optimum for callus induction. Increasing the numbers of sub-culture cycles improved the quality of calli. The optimum dosage for cell suspension culture ranged from 2.5 to 10 mL. The embryogenic callus suspension used in this study had a plant regeneration rate of 58%.

• 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.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.94-99
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• 2011

This study was performed to investigate the effect of foliar feeding as the fertilization on creeping benrgrass green. Research results have showed that the visual quality of bentgrass as well as shoot density and chlorophyll index dramatically improved after foliar feeding. Shoot density of bent grass in foliar based fertilization was 2.8 ea/$cm^2$ higher than that of the liquid based fertilization during the experiment period, moreover that the foliar feeding is more effective to alleviate shoot density during the rainy season in summer. Results showed that foliar feeding was key role to achieve the stable visual quality, chlorophyll index and maintained Normalized Difference Vegetation Index (NDVI) throughout the year in addition to get fast recovery after aeration and dry spot. These were consistent with the previous research of foliar feeding which directly provided nutrient to the turfgrass leaf thus increased turfgrass growth within a short time. It is projected to be a especially adequate management program during the hot summer season in which the nutrition feeding is low. However, root growth was no significant difference between foliar based fertilization and liquid based fertilization. Golf Course managers also should consider about the number of frequent fertilizing. Lastly, it was no big change in chemical property by soil foliar based fertilization which is meaning of preventing the soil salinization, meanwhile, it is prone to reach the nutrient deficiency. It hopes to be settled as the general fertilization in golf course of Korea, since there are many advantages of foliar based fertilization program. It is suggested to study more practical process of foliar feeding through the further research.