Background : Heat stress induced from high temperature are known to crucially affecting on physiological properties and yield in Cnidium officinale. Methods and Results : The effect of foliar application of mixture including a urea, ascorbic acid and calcium chloride on high temperature injury of Cnidium officinale. Photosynthesis and leaf temperature in Cnidium officinale were investigated after cultivating for 24 hours at 35℃. Net photosyntheis rate, transpiration was measured at 1,000 μmol m-2 s-1 of photon flux density and leaf temperature was analyzed by thermal image. Net photosyntheis rate, stomatal conductance and transpiration rate in mixture traetment were 2 times of higher than in control. Water use efficience was not different significantly. Leaf temperature was lower in mixture treatment (25.3℃) than in control (29.0℃). Conclusion : This result show that foliar application of urea, ascorbic acid and calcium chloride was reducing a high temperature injury through a improving photosynthetical capacity and decreasing leaf temperature of Cnidium officinale.

Background : Management of air temperature are known to primarily affecting on physiological properties and yield in plant. Methods and Results : The effect of air temperature on characteristics of photosynthesis and chlorophyll fluorescence in Cnidium officinal were investigated using growth chamber after cultivating for 24 hours under controlled condition. Net photosyntheis rate, transpiration was measured at 1,000 μmol m-2 s-1 of photon flux density and chlorophyll fluorescence was analyzed by OJIP method. Net photosyntheis rate was highest in treatment of 25℃. Although transpiration rate was lowest, water use efficience was also in treatment of 25℃. Stomatal conductance was mainly influenced from ambient climatric factors such as vapor pressure deficit. As results of chlorophyll fluorescence by OJIP analysis, maximum quantum yield (Fv/Fm) of photosystem II (PSII), PIabs and the relative activities per reaction center such as ABS/RC, DIo/RC were not changed at air temperature. Therefore, elevated air temperatue during short term influence the dark reaction in photosystem through controlling a water use efficience and transpiration. Conclusion : This result show that 25℃ of air temperature may be a adequate temperature to improving the efficiency of photosynthesis in Cnidium officinale.

Compared to wide ranges of genetic variation of natural populations, very limited Miscanthus cultivar has been released. This study was the first report on the development of Miscanthus cultivar by means of radiation breeding. Seeds of M. sinensis were initially exposed to gamma rays of 250 Gy for 24 h, generated from a 60Co gamma-irradiator. The irradiated seeds were sown and then the highly tiller-producing mutants were selected for this study. Biomass-related parameters including tiller number, plant height, stem diameter, and leaf number were measured. Ploidy level and internal transcribed spacer (ITS) were investigated to characterize the mutants compared to wild type (WT) Miscanthus. Plant height and tiller number were negatively related, where multi-tillering mutants were relatively short after 4 month growth. However stem diameter and leaf number were greater in mutants. All the materials used in this study were diploid, implying that the mutants with greater tiller numbers and stem diameter were not likely related to polyploidization. Based on the sequence of ITS regions, the mutants demonstrated base changes from the gamma irradiation where G+C content (%) was decreased in the ITS1, but increased in ITS2 when compared to WT sequence. ITS2 region was more variable than in ITS1 in the mutants, which collectively allows identification of the mutants from WT. Those mutants having enhanced tillers and allelic variations might be used as breeding materials for enhanced biomass-producing Miscanthus cultivars.