A Study on the Indices for Chilling Tolerance and Increasing Chilling Tolerance of Turfgrasses

• Main Authors: Hwi - Ching Lin, 林慧靜
• Other Authors: Yu-Sen Chang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/64344012980490039565

碩士 === 國立臺灣大學 === 園藝學研究所 === 89 === Summary Warm-turfgrasses is the main grasses for groundcovers of the parks in Taiwan. Low temperatures in winter always have harmful effects on physiological and morphological growth of warm-turfgrasses. The objectives of this study were to select the warm-turfgrasses with chilling resistance, to look for the index of chilling tolerance, and to research effects of Paclobutrazol (PP-333) and cold acclimation treatments on chilling tolerance of warm-turfgrasses. In the experiments for studying chilling tolerance of warm-turfgrasses, the relative growth rate of each grass (growth rate in low temperature (15/13℃) / growth rate in high temperature (30/25℃)) was used for comparing. In experiment 1(summer exp.), Zoysiagrass (Zoysia japonica.) had the best chilling tolerance, followed by Bahiagrass (Paspalum notatum cv. A33), Carpetgrass (Axonopus affinis), and Centipedegrass (Eremochloa ophuroides). Tropical Carpetgrass (Axonopus compressus) had the least chilling tolerance. In experiment 2(winter exp.), Bahiagrass ‘A33’ was the best chilling tolerance grass, next were Zoysiagrass, Bermudagrass ‘Sahara’, Centipedegrass, common Bermudagrass, and Carpetgrass. Tropical Carpetgrass was still the grass with least chilling tolerance. Hence, Zoysiagrass and Bahiagrass ‘A33’ were the warm-turfgrasses with better chilling tolerance, and Tropical Carpetgrass was the weakest grass under low temperatures. To research indexes for chilling tolerance, chlorophyll fluorescence, electrolyte leakage, and chlorophyll meter reading (CMR) values were measured for evaluating. From the results of measuring chlorophyll fluorescence in experiment 1(summer exp.), the PSII photochemical efficiency (Fv/Fm) of Centipedegrass decreased and recovered faster than other tested grass species, followed by, Zoysiagrass, Carpetgrass , and Bahiagrass ’A33’. The Fv/Fm value of Tropical Carpetigrass decreased very slowly and went down to the lowest level. In the experiment 2(winter exp.), the electrolyte leakage of Tropical Carpetgrass was the highest, followed by Carpetgrass, Common bermudagrass, Improved bermudagrass, Zoysiagrass, Centipedegrass, and Bahiagrass was the lowest. Except for Centipedegrass which value increased all the time, the CMR values of warm-turfgrasses under low temperature decreased in the beginning and then increased later. There were significant positive correlations between the relative growth rate and the relative Fv/Fm ratio which measured at the 6,8 days after chilling treatment beginning, and the r were 0.69**, 0.92***(n=15). There were significant negative correlations between the relative growth rate and the relative electrolyte leakage (%) which measured after chilling treatment beginning, the r were 0.86**(n=21). There were significant positive correlations between the relative growth rate and the relative CMR values (%) which measured after chilling treatment beginning, and the r were 0.80***(n=21). The results showed that PSII photochemical efficiency, electrolyte leakage, and CMR can be reliable tool to predict the growth rate of warm-turfgrasses under low temperature. To study the effect of PP-333 on chilling tolerance of Tropical Carpetigrass, 25 ppm PP-333 were applied to the shoots. The shoot length was shorter than control treatment. Both the PSII photochemical efficiency and the CMR value were higher than that of the control treatment, whereas the electrolyte leakage were lower than that of the control treatment. The results showed that PP-333 could inhibit the growth of Tropical Carpetigrass, increased photosynthesis efficiency, decreased the destruction of cell memberance and chlorophyll. In winter, 35 ppm or 70 ppm PP-333 were drenched to the soil or sprayed on the shoots of Tropical Carpetigrass. The results showed that the shoot length was the longest with 35 ppm by spraying, next were 35 ppm by drenching and 70 ppm by spraying. The shortest of shoot length was 70 ppm by drenching. However, the changes of Fv/Fm, electrolyte leakage and CMR value of PP-333 treatments were not identical with the PP-333 concentration or application methods. To study the effect of temperatures on the growth and development of Tropical Carpetigrass, that results showed that the growth (include shoot length and leaf number) of Tropical Carpetigrass in 30/25℃(day/night) was the best, followed by plants grown in 25/20℃ and 20/15℃. The worst was in 15/13℃. The Fv/Fm ratio of Tropical Carpetigrass grown in 30/25℃ was the highest, and then were the plants grown in 25/20℃ and 20/15℃. The lowest value appeared on the plants grown in 15/13℃.The condition of CMR value was similar to the Fv/Fm ratio, whereas the electrolyte leakage of plants grown in 30/25℃ was the lowest , followed by the plants grown in 25/20℃, 20/15℃, and the 15/13℃was the highest. The effects of transported temperature treatments on growth and development of Tropical Carpetigrass were that the treatment of reduced the temperature weekly had the highest level of Fv/Fm and without significantly fell down. Three-week high temperature treatment and two-week high temperature treatment were decreased to the lowest level and recovered fast at the 3rd day after chilling treatment beginning. One-week high temperature treatment fell down and recovered slowly. Electrolyte leakage was least on plants grown under the temperature reduced weekly, and then were the three-week high temperature treatment and two-week high temperature treatment. One-week high temperature treatment had the highest electrolyte leakage. The CMR values of the plants grown under the temperature reduced weekly and plants of the three-week high temperature treatment were higher. The CMR values of plants of two-week and one-week high temperature treatments decreased significantly, but the CMR values of plants of two-week high temperature treatment recovered faster than that of one-week high temperature treatment. The plant size (include shoot length and leaf number) after transported to low temperature was the highest on plants of three-week high temperature treatment. And then were that of two-week high temperature treatment and the plants under temperature reduced weekly. The growth rate of plants of one-week high temperature treatment was the lowest. The results showed that the cold acclimation can increase photosynthesis efficiency of Tropical Carpetigrass, and reduce the destruction of cell merbrance and chlorophyll.