Hydroseeding technique is a very popular method of revegetating slope areas through the control of soil erosion and stability by seeding grasses. This study was conducted to select turfgrass species and cultivars for hydroseeding. Experiment plots were established on various soil types and environmental conditions at Singar-Ansan high-way construction site. The investigation was designed in three cutting, one back-filling and other three spare sites with various seed mixtures. Results indicated that combinations of seed mixtures influenced seed germination and rates of surface cover. In a view of long term, vegetation shifts should be influenced by characters of slopes and micro-climate conditions. Hydroseeding did not show good results on rocky slope areas. Revegetation was only going on where there had soil. The combination of seed mixture with a higher rate of perennial ryegrass had relatively good revegetation with faster germination and seedling growth. Improved turf-type tall fescue Arid ⓡ and Falcon ⓡ seemed to have good environ-mental adaptation and drought tolerance. Wild or old type cultivars showed relatively slow green-up in spring and growth rates at the next year of seeding. For the harmonious landscaping with surrounding area, the combination of native grass mixture with cool-season grasses had good results. Slow and low revegetation rate at hack-filling site seemed to be caused by the poor development of capillary tubes in sub-soil. It was shown that a high correlation between seed germination and revegetation rate, and between three-month later coverage rate and final rate. The evaluation of coverage rate after three month seems to he acceptable to decide the accomplishment of hydroseeding results on rode side slopes.

The objective of this research was to produce sod by box seeding for zoysiagrass or by vegetative propagation for zoysiagrass and manilagrass.1 Various ratio of peatmoss to sand(v /v) were prepared to find idea[ medium for fast and light weight sod production. Then, the days required for sod formation, the effect of growth regulators on the growth of turfgrass, and the various storage methods for winter keeping of sods were also investigated. 1.The mixed medium of sand and peatmoss(v /v, 1 : 2) showed more biomass production than that of sand. 2.In comparison of seeding rate of zoysiagrass, the amount of log /$m^2$ was most effective in the fast and dense sod formation. The amount of 20g /$m^2$ also showed fast sod formation. But, it resulted in weak plant and less tillering. During April to June, about 100 days were required to form sod with seeding rate of 5g /$m^2$ regardless of seeding time. Whereas 80 days were required to form sod in the rate log /$m^2$, which was 20 days shorter than that of 5g /$m^2$. 3.More than 85% of shoots in sod stored in field or plastic house during the winter time resumed the growth in good appearance after transplanting. The whole covering of ground with sod resulted in less weeds and faster formation of lawn. 4.Vegetative propagation of manilagrass showed about 7 to 15 days faster formation of sod than that of zoysiagrass. Application of GA increased shoot growth and BA increased the total number of tillering. However, the effects of the combined application of GA and BA were negligable.

This study is aimed to clarify on the influence of cultivated conditions and fungicides on development of Rhizoetonia diseases of zoysiagrass and creeping bentgrass and results are as follows. Infection rates of disease were observed more serious when inoculum amounts were higher than low. Effects of the watering intervals on the severity of disease with artificial inoculating conditions, infection rates were higher when two days watering interval for creeping bentgrass and one day interval for zoysiagrass. Disease severity of creeping bentgrass incited by Rhizoetonia solani AG 1 (1A) was grater under conditions of double amounts of nitrogen fertilization. A posi- tive correlation was founded between the pH and disease development. The pots with pH 5 and 8 were significantly more diseased grass than those in which the pH was in 6.5. Mepronil and myclobutanil were extremely effective against brown patch of creeping bentgrass and large patch of zoysiagrass and followed by capro, and tebeonazole. Fenari was inferior effect to both diseases.

This experiment was conducted to investigate the effect of the nitrogen fertilization levels on the content of $NH_4^+$-N in soil of 'Suffolk' Kentucky bluegrass and zoysiagrass. The results obtained are summarized as follows : 1.According to the nitrogen fertilization levels, the content of $NH_4^+$-N in soil of Kentucky blue-grass and zoysiagrass was not significantly different. The content of $NH_4^+$-N in soil of Kentucky bluegrass and zoysiagrass was highest in June and December and lowest in March and September. 2.The content of $NH_3^-$-N in soil was increased by increasing the nitrogen fertilization levels in both Kentucky bluegrass and zoysiagrass. However, the deeper the depth of soil the less the content of $NO_3^-$-N in soil. In 40~60cm soil depth, the content of $NO_3^-$-N in soil was lower than 10ppm in average. Even in June, which was the highest month of the content of $NO_3^-$-N in soil, the content of $NO_3^-$-N in soil was not overpassed the degree of 20ppm.

The study is aimed to understand effects of ethephon(lmg/1), ABA(0.lrng/l), BA(0.lmg/l). and NAA (0.lmg /1) soaking treatment on the seed germination of perennial ryegrass 'Dandy', creeping bentgrass 'Penlinks', tall fescue 'Arid' and kentucky bluegrass 'Nasaw'. These experiments are carried in vitro and their results are summarized as the followings ; In case of ethephon (lmg /1) soaking treatment of seed, the early germination of tall fescue 'Arid' and perennial ryegrass 'Dandy' was good without the soaking times. creeping bentgrass 'Penlinks' and kentucky bluegrass 'Nasaw' obtained the best results at 12 hr. soking treatment, and the longer the soaking time, the higher the germination percentage. The early germination percentage of tall fescue 'Arid' and perennial ryegrass 'Dandy' increased more highly at ABA(0. tmg /1) soaking treatment than at the control. The germination percent-age of creeping loentgrass 'Penlink' and kentucky bluegrass 'Nasaw' had respectively the best results at 6hr. and l2hr. soaking treatment. The early germination percentage of tall fescue 'Arid' and kentucky bluegrass 'Nasaw'increased more highly at BA (0.lmg /1) soaking treatment than at the control, and especially had the best results in 6hr. soaking treatment. perennial ryegrass 'Dandy' had the best results at l0min. soaking treatment, and the longer the soaking time, the lesser the germination percentage. The early germination of perennial ryegrass 'Dandy'. creeping bentgrass 'Penlinks' and tall fes- cue 'Arid' increased more highly at NAA (0.lmg /1) soaking treatment than at the control, and especially had the best results at l2hr. soaking treatment. However, the germination of Kentucky bluegrass 'Nasaw' seeds inhibited at NAA (0.lmg /1) soaking treatment. Key words: Ethephon, ABA, BA, NAA, Soaking treatment, Seed germination.

The Widespread and most abundant grasses are Miscanthus sinensis and Pteridium aquilinum in the grassland of Cheju-Island. The vascular flora of the grassland are composed of 127 species in all. Those communities of Miscanthus sinensis Pteridium aquilinum Imperata cylindrica Themeda japon-ica and Zoysia japonica are relatively homogeneous. Standing crops of the mixed grass communities range from 657 g /$m^2$ to 2, 975 g /$m^2$ on August 30, and the value of daily net production is around 2.6~121 g/$m^2$. The standing crop of north facing slop showed higher than that of south facing slop. Relationship between the standing crop and water content, organic matter, total nitrogen and available phosphorus of soils in Cheju-Island showed high level of significant.

Turfgrass Rhizoctonia blight is a severe disease in golf courses in Korea. Attempts were made in 1989 to 1994 to identify the Rhizoctonia species associated with turfgrass blights and also to examine their epidemiology. A total of 120 Rhizoctonia isolates collected were identified as R. solani AG1, R. solani AG2-2, R. cerealis(AG-D) and R. oryzas from brown patch, large patch, yellow patch and white patch, re-spectively. R. solani AG1 was mostly associated with brown patch of cool-season grasses. and most frequently isolated in June through July and also in September. R. solani AG2-2 was isolated exclusively from zoysiagrasses from April to November, most frequently in June through July and October through November. R. cerealis was isolated frequently from both creeping hentgrass in March through April and in November, and zoysiagrass in April and July. Thermophilic R. oryzae was isolated only from creeping bentgrass in August, although with very low frequency. R. solani AG2-2 was strongly pathogenic specifically to Korean lawngrasses(Zoysia japonica, Z.matrella, Z. tenuifolia), but non-pathogenic to creeping bentgrass(Agrostis palustris), bermudagrass (Cynodon dactylon), Kentucky bluegrass(Poa pratensis), perennial ryegrass(Lolium prenne), and creeping red fescue(Festuca rubra subsp. ruhra L.). R. cerealis was strongly pathogenic to zoysiagrass and bentgrass only, but was isolate-specific i.e., from non-pathogenic to pathogenic, for other turfgrasses. The mycelial growth was optimum at relatively high temperature ranges of 25~30$^{\circ}C$ for R.solani AG1, AG2-2 and R. oryzae, while the mycelial growth of R. cerealis was initiated at $^{\circ}C$ and almost ceased at or above $^{\circ}C$.

This study is aimed to understand the effects of temperature, light and GA soaking treatment on the seed germination of perennial ryegrass 'Dandy', creeping hentgrass 'Penlinks', tall fescue 'Arid' and Kentucky hluegrass 'Nasaw'. These experiments are carried in vitro, and their results obtained are summarized as the followings ; The optimum temperature for seed germination of perennial ryegrass 'Dandy' was found to he ranged at 20~30$^{\circ}C$, and the optimum temperature for germination of creeping bentgrass 'Penlinks', tall fescue 'Arid' and kentucky bluegrass 'Nasaw' seeds was found to be ranged at 20~25$^{\circ}C$, whereas the germination percentage under the below or above temperature of this range decreased. The germination of perennial ryegrass 'Dandy' and tall fescue 'Arid' seeds showed no effect on light, and while the germination percentage of creeping hentgrass 'Penlinks' increased more highly under the dark condition than under the light condition. The germination percentage decreased according to the higher temperature. The germination of Kentucky bluegrass 'Nasaw' seeds increased more highly under the dark condition than under the light condition at 20~25$^{\circ}C$, whereas the germination percentage under the dark condition at 15$^{\circ}C$ and 30$^{\circ}C$ decreased. In case of GA soaking treatment of seeds, all the cool season turfgrasses tested showed their own promoting effects on seed germination. The early germination of tall fescue 'Arid' was good without the soaking times. Creeping bentgrass 'Penlinks' and perennial ryegrass 'Dandy' had re-spectively the highest germination percentage at 10min and 1hr soaking treatment, and the longer the soaking time, the lesser the germination percentage. Kentucky bluegrass 'Nasaw' obtained the best results at 24has soaking treatment, and the longer the soaking time, the better the ger-mination percentage.