To compare the vitality among cool-season turfgrasses under summer weather conditions and to obtain information to improve the management of turfgrasses in golf courses and sports fields., the chlorophyll fluorescence of three cool-season turfgrasses commonly planted on golf courses in the Jeju area was measured. The turfgrasses were perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), and creeping bentgrass (Agrostis palustris Huds.). In perennial ryegrass and Kentucky bluegrass, the chlorophyll index was low in early summer and high in late summer. In creeping bentgrass, it remained low throughout the study. Fo tended to be low in the early summer and high in late summer in the three turfgrasses. However, the difference in Fo between late summer and early summer was markedly higher in perennial ryegrass than in Kentucky bluegrass or creeping bentgrass. Fm tended to be low in early summer and high in late summer, without obvious differences among the three turfgrasses. Fv/Fm, a measure of photochemical efficiency, was also low in early summer and high in late summer in the three turfgrasses. However, Fv/Fm in late summer was mostly higher in Kentucky bluegrass and creeping bentgrass than in perennial ryegrass, indicating that the former are more resistant to the high temperature and humidity of late summer. Furthermore, Kentucky bluegrass had a high chlorophyll index in late summer and would be most resistant to the harsh conditions of late summer.

Abstract
1. 서 론
2. 재료 및 방법
    2.1. 조사 장소 및 기간
    2.2. 식물재료
    2.3. 기상자료의 수집
    2.4. 엽록소형광과 엽록소지수의 측정
    2.5. 통계 분석
3. 결과 및 고찰
    3.1. 기상요인 분석
    3.2. 엽록소지수의 변화
    3.3. 엽록소형광의 변화
4. 결 론
REFERENCES

• 고석찬(제주대학교 생물학과) | Seok Chan Koh (Department of Biology, Jeju National University) Corresponding author