Miscanthus has been considered as the most promising bioenergy crop for lignocellulosic biomass production. In Korea, M. sacchariflorus and M. sinensis can be found easily in all regions. It is a great advantage to utilize as important species with respect to genetic and cross-breeding programs materials for creation of novel hybrids. For successful breeding programs, it is important to precisely understand the variability of flowering traits among Miscanthus species as breeding parents materials. In this study, flowering traits were observed daily in 960 germplasms of two Miscanthus species (M. sacchariflorus and M. sinensis) for growing seasons over 2 years. The flowering process was divided into three stages. ST (sprouting time) was recorded when first leaf of the plant emerged on soil. FS1 (flowering stage 1) and FS2 (flowering stage 2) were recorded when flag leaf was firstly observed, and 1 cm of panicle was showing on at least one stem, respectively. For 2013 and 2014, the latest germplasms exerted flag leaf, i.e. September 30 (DOY of FS1 164.1) and September 4 (DOY of FS1 141.0) occurred M. sacchariflorus cv. Geodae 1 and M. sacchariflorus cv. Uram collected from Southern Korea (Jeollanam-do), while Miscanthus germplasms collected from northern Korea (Gyeonggi-do) which emerged the earliest flag leaf in July and August, significantly decreased DOY. For DOY from ST to FS2, M. sacchriflorus germplasms ranged from 140 to 190 days, and 110 to 170 days for 2013 and 2014. The highest frequency showed to 160 days for 2013, and 150 days for 2014. In M. sinensis germplasms, the highest frequency showed to 180 days for 2013, and 170 days for 2014. In the results of correlation between the day of years from ST to FS2 for 2013 and 2014, M. sacchriflorus and M. sinensis showed high coefficient of correlation (0.70 and 0.89). It can be supposed that flowering characteristics of Miscanthus are largely affected by the unique phenotypic characteristic of native habitat than environmental factors of the current planted site. This study for flowering traits of Miscanthus may provides an important information in order to expedite the introduction as breeding materials for creation of new hybrid.
This study was carried out to establish the optimal conditions for callus induction and plant regeneration using immature inflorescence of M. sacchariflorus cv. 'Wooram', a bioenergy crop selected in Korea. Callus induction rate was the highest (93.3%) in MS medium containing 3 mg L-1 2,4-D, and 86.7% in MS medium containing 3 mg L-1 2,4-D combined with 0.1 mg L-1 BA. Plant regeneration rate was high when the calli derived from the medium containing BA was used, as compared with those derived from the BA-minus medium. The results showed that the medium conditions containing 5 mg L-1 BA combined with 0.1 mg L-1 NAA was the most effective in plant regeneration of which the rate reached 86.7%. The regenerated shoots were separated from the calli and roots over 3 cm were developed from the shoots after 4 week culture on basal MS medium without supplementation. The plantlets were then transferred to soil and cultured in greenhouse. After 5 weeks, the plants with the height of at least 20 cm were successfully acclimatized.
This study was firstly conducted to investigate changes of vegetation and soil characteristics in reclaimed land applied with solidified sewage sludge for the cultivation of bioenergy crops. Each vegetation survey site was approximately 15 m × 3 m on the inside of each experimental plot that consisted of 50% (A-1), 30% (A-2), 15% (A-3), and 5% (A-4) mixture of solidified sewage sludge, and original reclaimed soil (ORS). After the application of solidified sewage sludge, we monitored the changes of vegetation and soil properties for three years. In first year, soil pH, electrical conductivity (EC) and exchangeable Ca 2+ content was 9.4 ~10.8, 9.10~14.41 dS m -1 , and 62.1~204.2 cmol kg -1 , respectively, while three years later, it decreased to 8.1~8.4, 1.65~5.98 dS m -1 , and 21.9~43.1 cmol kg -1 , respectively. These results indicated that several of soil chemical elements which have nagative impacts on the plant growth in the plots of mixtures of solidified sewage sludge, steadily declined as the years go by. The vegetations in each survey site were recorded as 6 families and 12 species in 2014, while the vegetations were not occurred at all survey sites in 2012, and only halophytes as Phragmites australis and Suaeda asparagoides were observed in 2013. Diversity of vegetation, which was calculated by shannon index (H'), increased as the season progressed at each experimental plot applied with solidified sewage sludge. In original reclaimed soil, however, there was showed the high community similarity of vegetation due to the fact that P. australis and S. asparagoides were only occurred for survey periods.
The rice stem borer (Chilo suppressalis Walker) was one of the most destructive pest of rice for the 1960s and 1970s in Korea. Recently, it is newly recognized as a potential risk factor to the biomass yield of bioenergy crops. The current research was firstly conducted to investigate overwintering larvae population density and pattern of rice stem borer attacking Miscanthus sacchariflorus cv. Geodae 1 which is referred to as an ideal lignocellulosic bioenergy crop in Korea. Population density of larvae per 1 m 2 in stems and rhizomes at the Miscanthus experimental plots and rates of damage (wormhole, abscission) of M. sacchariflorus cv. Goedae 1 were investigated from October 2012 to March 2013. The population of larvae per 1 m 2 in stems of Miscanthus were 23, 4, 1, and 1 in October, November, December 2012, and January 2013, respectively. Over the same period, the population of larvae in basal stem rots and rhizomes were increased, whereas decreased in stems. Interestingly, the positions of larvae for overwintering in Miscanthus were confirmed to 5~10 cm below the soil surface such as basal stem rot and rhizome, whereas the most common overwintering position known in rice is a part of stem on the ground such as rice straw and rice stubble. It would suggest that the larvae gradually moved to bottom of stems and rhizomes in soil in line with decline in temperature. Moreover, the damage rates of stems per 1 m 2 were up to more than 50% in some places. In conclusion, this might be the first report that rice stem borer could affect the productivity of biomass of Miscanthus in case of mass cultivation. Moreover, it should be necessary to make a decision in insect control management for this bioenergy feedstock and other related crops.
ABSTRACT.Miscanthus are perennial rhizomatous grasses and considered as an ideal cellulosic bioenergy crop. Recently, it was reported that Miscanthus was damaged by the larvae of rice stem borer, Chilo suppressalis Walker, one of the most destructive pests of rice in Korea since the 1960s. This study was thus conducted to evaluate the insecticidal effects against rice stem borer in the Miscanthus cultivation fields for two years. The experiment consisted of four chemical agent plots, one environment-friendly agent plot, and untreated plot. Untreated plot showed significantly high damage of 50%, while Buprofezin·Tebufenozide and Carbosulfan·Methoxyfenozide treatment plots showed low damage rate of 2% with low larvae density of 1 and 2.3 larvae m −2 , respectively. Damage rates of Tebufenozide, ChlorantraniliproleIndoxacarb, and environment-friendly agent(MatrineWood vinegar solution) were 15, 26, and 18%, respectively, which were lower than that of untreated plot but higher than those of Buprofezin·Tebufenozide and Carbosulfan·Methoxyfenozide. In conclusion, rice insecticides were effective against rice stem borer in Miscanthus field. In particular, the treatments with Buprofezin·Tebufenozide and Carbosulfan·Methoxyfenozide showed excellent control effects with control value of 93.3 and 95.2. However, further studies with different types of insecticides should be carried out for the selection of insecticides with more effective control of rice stem borer.
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