Genetic Diversity of Miscanthus spp. in Photosynthesis

학위논문 (석사)-- 서울대학교 대학원 : 식물생산과학부 작물생명과학 전공, 2013. 2. 김도순.Miscanthus, a weed thriving in South-eastern Asia and some parts of Africa, is a well-known potential biomass grass due to its C4 photosynthesis and high biomass potential in temperate region. Its photosynthetic ability under low temperature and shaded condition when canopy closed is considered as an important trait in determining biomass yield potential. Thus, the objectives of this study were to investigate the photosynthetic ability under low temperature and shaded conditions and the photosynthetic diversity of different Miscanthus accessions with relation to its biomass yield. Three factors were examined: temperature effects when the plants were exposed to 25/20oC, 20/15oC, and 15/10oClight intensity effects when the plants are exposed to varying light intensities of 100%, 75%, 45%, 25%, and 5%and genotypic variation in photosynthetic ability and biomass yield using 53 three-year stands accessions measured in the field condition. Results show that lower temperature and shaded condition tend to limit the photosynthetic ability of the plant but the trends of declining with decreasing temperature and light intensity depend on species and accessions. Miscanthus lutarioriparius was most sensitive to low temperature in photosynthesis and biomass yield responses, while M. sacchariflorus was the second least sensitive in photosynthesis and M. sinensis in biomass yield response after M. x giganteus, which was most insensitive to low temperature in photosynthesis and biomass yield responses. Miscanthus sacchariflorus was most insensitive to low light intensity in photosynthesis, while M. sinensis was most insensitive in biomass yield. Therefore, it can be concluded that under low temperature and low light intensity, M. sacchariflorus can maintain stable photosynthesis and M. sinensis can maintain more stable biomass yield. The field study with 53 accessions showed diversity in physiological parameters including photosynthesis and biomass yield but no significant correlation between photosynthesis rate and biomass yield, suggesting that biomass yield may not solely explained by photosynthetic rate measured on a specific spot of a leaf but by whole plant photosynthetic ability comprised of whole leaf area and photosynthesis rate. Miscanthus lutarioriparius and some M. sinensis accessions, M-14, M-96, M-107 and M-177, showed high biomass yield even with low photosynthesis. They may be a good source for breeding a new variety as a biomass crop and for further study to understand the relationship between photosynthesis and biomass yield.1. INTRODUCTION....................................................................1 2. LITERATURE REVIEW.........................................................2 2.1 Miscanthus as a potential bioenergy crop...............................2 2.2 Photosynthetic ability of Miscanthus in relation with biomass production...............................................................................3 2.3. Effects of low temperature on photosynthesis and biomass yield.......................................................................................4 2.4 Developing a new Miscanthus variety for biomass production in temperate regions................................................................5 3. MATERIALS AND METHODS..............................................6 3.1 Plant material .........................................................................6 3.2 Photosynthetic responses under low temperature condition...6 3.3 Photosynthetic responses under low light intensity................7 3.4 Diversity of Miscanthus spp. in photosynthetic ability...........8 3.5 Statistical analysis...................................................................8 4. RESULTS AND DISCUSSIONS...........................................11 4.1 Effect of low temperature on photosynthetic responses of Miscanthus spp……………………………………….....11 4.2 Effect of low light intensity on photosynthetic responses of Miscanthus spp.................................................................23 4.3 Diversity of Miscanthus spp. genotypes in photosynthetic abilities..............................................................................36Maste