S-Space College of Agriculture and Life Sciences (농업생명과학대학) Dept. of Plant Science (식물생산과학부) Theses (Ph.D. / Sc.D._식물생산과학부)
Genetic Diversity and Biomass Yield Potential of Korean Miscanthus
- 농업생명과학대학 식물생산과학부(작물생명과학전공)
- Issue Date
- 서울대학교 대학원
- Agronomic trait; biomass yield; breeding; canopy structure; genetic diversity; Miscanthus; morphological trait
- 학위논문 (박사)-- 서울대학교 대학원 : 식물생산과학부(작물생명과학전공), 2015. 8. 김도순.
- Miscanthus is a potential bioenergy crop due to its C4 photosynthesis, perennial and rhizomatous growth, rapid growth and high biomass productivity, and broad environmental adaptability. Korea is known as a core region that has diverse Miscanthus genetic resources. Particularly M. sinensis and M. sacchariflorus, which are considered to be two most important parental candidates for developing high yield cultivars, are native to Korea. However, no study has been reported to evaluate genetic diversity and biomass yield potential of Korean Miscanthus. Therefore, this study was conducted to investigate genetic diversity by assessing morphological, phenological and agronomic traits of Korean Miscanthus and to evaluate biomass yield potential by determining the relationships between phenological, canopy structural and agronomic traits with biomass yield in a field located in Suwon and Yeoju, Korea for 5 years from 2010 to 2014.
To investigate genetic diversity by morphological traits, 280 Miscanthus accessions that consist of 184 M. sinensis and 93 M. sacchariflorus collected from Korea and other East Asian countries including China, Japan, and Russia were planted in the Miscanthus germplasm field located in Suwon, Korea in 2010. Three reference accessions, one M. × giganteus, one M. floridulus, and one M. lutarioriparius, were also planted. Twenty morphological traits in leaf, stem, and inflorescence were assessed and then used for phylogenetic analysis. Among these traits, the presence of awn in spikelet, stem growth habit, new autumn shoot emergence, and the ratio of callus hair to spikelet were the key traits to distinguish between M. sinensis and M. sacchariflorus, while the other traits were associated with genetic diversity among accessions within the same species or the same cluster. Both M. sinensis and M. sacchariflorus were individually clustered into five groups with M. floridulus belonging to M. sinensis IIa group, while M. lutarioriparius and M. × giganteus into M. sacchariflorus V group. Principal coordination analysis (PCoA) of morphological traits found 24 intermediate accessions, seven M. sinensis and 17 M. sacchariflorus, positioned between M. sinensis and M. sacchariflorus. Chromosome counting revealed that five accessions, one M. sinensis and four M. sacchariflorus, were triploid, suggesting natural hybrids between M. sinensis and M. sacchariflorus.
Traits associated with biomass yield such as phenological and agronomic traits were assessed in the four-year field trial in Suwon, Korea from 2010. Correlation analyses among phenological and agronomic traits, biomass yield and geographic latitude of collection site showed that heading date, leaf growth traits and stem growth traits were closely related with biomass yield. Latitude and heading date exhibited a significant negative correlation, and heading date showed a significant positive correlation with biomass yield. The presence of significant relationships between latitude and agronomic traits suggests that the accessions collected from different geographical latitudes can provide more genetically diverse materials for breeding. The growth of top three leaves (flag, the second and the third leaf) showed positive correlation with other agronomic traits such as stem diameter and stem dry weight, and then biomass yield. Agronomic traits assessed in the second year after planting also had a strong correlation with biomass yield assessed in the fourth year after planting. In particular, the leaf area, stem diameter and stem dry weight of the second year were significantly related with the fourth year biomass yield. It suggested that the earlier agronomic traits assessed in the s year can be used for screening Miscanthus genetic resources and lines with high biomass yield potential. Despite of general relationships between phenological and agronomic traits and biomass yield, poor relationships were often observed between traits and latitude collection sites. These diverse patterns of relationship with phenological and agronomic traits imply that the tested Miscanthus accessions possess high genetic diversity in their biomass yield potential.
For better understanding of biomass formation in Miscanthus and establishing an ideo-type with high biomass yield for future breeding, canopy structures of 17 Miscanthus accessions, 8 M. sinensis, 6 M. sacchariflorus, and 3 triploid Miscanthus, were assessed in the field located in Yeoju, Korea, for 3 years from 2012 to 2014. Canopy diameter, canopy height, canopy area and canopy volume of each plant were measured together with no. of stem and stem dry weight per plant every year, and then stem no. per canopy area, stem dry weight per canopy area, and stem dry weight per canopy volume were calculated. Annual canopy development rates in all the canopy-associated parameters were finally estimated by linear regression analyses. Canopy area and volume of M. sinensis were relatively slowly developed due to its rhizome growth habit as compared to M. sacchariflorus and triploid Miscanthus, which show rapid outwards rhizome growth. Regarding biomass accumulation per a unit area and volume of canopy, M. sinensis showed greater biomass density due to its compact growth habit than M. sacchariflorus, while triploid Miscanthus showed intermediate biomass accumulation. These results suggest that canopy developmental traits are dependent on Miscanthus species thus it can be used for discriminating Miscanthus species. Correlation analyses of canopy traits with agronomic traits and biomass yields revealed that canopy diameter, canopy height, canopy area and canopy volume are significantly related with biomass yield, but the extent of significance of these relationships depends on Miscanthus species. In M. sinensis, canopy volume followed by canopy diameter and canopy area were the most determinant for biomass yield, while canopy height followed by canopy diameter and canopy volume in M. sacchariflorus and canopy diameter followed by canopy area and canopy volume in triploid Miscanthus were the most important determinant. These results suggest that for biomass production, outwards expansion of canopy structure is important for M. sinensis and triploid Miscanthus, while vertical expansion of canopy structure is important for M. sacchariflorus. Therefore, canopy parameters provided a clue of desirable canopy structure of Miscanthus for future breeding toward greater biomass yield potential of Miscanthus cultivar.