Determination of the Optimum Dose Range for a Mutation Induction of Turfgrasses by a Gamma-Ray

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.

잔디류 돌연변이 유기를 위한 적정 방사선 선량범위의 결정

본 연구는 잔디종자에 감마선을 조사하였을 때 종자 발아율 및 초기 생육을 관찰하여 잔디 종류에 따른 방사선 감수성을 관찰하고 돌연변이 유기를 위한 적정 방사선 선량을 결정하고자 수행되었다. 난지형 잔디인 zoysiagrass, bermudagrass, seashore paspalum과 한지형 잔디인 Kentucky bluegrass, tall fescue, perennial ryegrass, creeping bentgrass를 실험에 사용하였다. 다양한 방사선 선량으로 24시간 처리한 후 발아율 및 신초, 뿌리 길이와 생체중을 조사한 결과 방사선 선량이 증가할수록 발아율 및 초기 생육이 감소하는 것으로 나타났다. 감마선에 의해 생육이 50% 억제되는 반치사선량을 조사한 결과 잔디 종류에 따라 다양하게 관찰됨을 알 수 있었다. 잔디 종류별 반치사선량 ($LD_{50}$)은 zoysiagrass, seashore paspalum, bermudagrass, Kentucky bluegrass, perennial ryegrass, tall fescue, creeping bentgrass 각각 300, 150, 600, 150, 200, 100, 200 Gy로 bermudagrass가 가장 높고, tall fescue가 가장 낮게 나타났다.