Young-Son Cho

Effect of Drying Methods on the Saponin and Mineral Contents of Platycodon grandiflorum Radix

This study was conducted to provide basic information about the drying methods (daylight, hot-air, and freeze drying) used for Platycodon grandiflorum radix. We investigated the mineral, free sugar, and saponin contents of dried P. grandiflorum. The potassium and calcium contents of hot-air-dried samples were the highest (22.6 and 9.2 mg%, respectively), when compared to those of daylightor freeze-dried samples. Glucose and sucrose contents were the highest in freeze-dried samples (1,552 and 145.0 mg%, respectively), while fructose content was the highest in hot-air-dried samples (611.9 mg%). Platycodin D content was the highest in hot-air-dried samples (622.0 mg%); however platycodin D3, polygalacin D, and deapioplatycodin D contents were the highest in daylight-dried plant (113.5, 756.6, and 109.2 mg%, respectively). Glucose content was highly negatively correlated (p<0.01) with platycodin D, platycodin D3, and deapioplatycodin D (−0.924, −0.957, −0.861, p<0.01, respectively). These results suggest that the drying method affects the saponin content of P. grandiflorum and daylight and hot-air drying methods are more suitable and beneficial than freeze-drying.

Diversity of Soil Microbial Communities Formed by Different Light Penetrations in Forests

The present study investigated variations in soil microbial communities and the chemical properties of forest soils by differing amounts of penetrating sunlight. The soil temperature was significantly higher in higher light-penetrated soils. Higher light-penetrated soils (LP70) showed significantly more fungal communities than the lower light-penetrated soils (LP40 and LP50) (p 4- N concentration in LP70 was significantly lower than those of LP40 and LP50, whereas the other chemical properties showed no significant difference among the soils. The cy19:0 to 18:1ω7c ratio was significantly lower in LP70 than in LP 40 and LP50 showing the negative correlation of light level with microbial stresses (p 4- N, actinomycetes, Gram-negative bacteria, and bacteria. Consequently, the amount of penetrating light was responsible for microbial compositions in the forest soils in correlation with the concentration of NH 4- N and soil temperature.

Differences of Soil Carbon by Green Manure Crops in Rotated Cropping System

This experiment was conducted to select winter-adaptable crop system or cropping systems for an enhanced carbon (C) fixation amount in plant biomass and soil. Single or mixed cropping systems of green manure crops, rye (R), triticale (TC), hairy vetch (HV), TC+HV, and control (fallow) were investigated during winter and spring. The amount and content of C and N in the above-ground biomass and soil C content by soil depth were measured under different green manure crops. The above-ground biomass was highest in TC+HV followed by R and TC with 664, 585, and 545 kg , which exceeded the biomass of control by 181, 160, and 149%, respectively. The amount of C accumulation was higher in soil surface than deep soil. which was a similar pattern to the above-ground biomass. Therefore, green manure cropping in winter and spring seasons will be very helpful of improve soil organic matter.

Effects of Planting Density and Mulching Method on Growth and Yield of Sorghum ( Sorghum bicolor L.)

This study was conducted to evaluate effects of planting densities (60 × 10 cm, 60 × 20 cm, 60 × 30 cm) and mulching method (polyethylene plastic (P.E.), open) for 2 years in sorghum field. In P.E. plots, culm length, culm diameter and fresh weight were higher than non-mulched plot. Additionally, spike length, seed weight per hill and thousand seed weight were also higher at P.E. plot than non mulched plot. The seed yield of sorghum were higher 116% and 132% at P.E. plot than non-mulched plot in 1 and 2 year, respectively. In mulched plot with 60 × 30 cm planting distance, culm length were 21.5 and 23.3 cm in 1 and 2 year which were higher than non-mulched plot, however culm diameter were higher in non-mulched plot than mulched plot without statistical significance. The growth characteristics were positively related with planting density, however, yield related characteristics, spike length, seed weight per hill and thousand seed weight, were negatively related with planting density. The seed yield was highest at 60 × 20 cm plot 451 and 357 kg 10 a− in 1 and 2 year, respectively. And it was followed by 60 × 10 cm plot and 60 × 30 cm plot.