Hak-Yoon Kim

P effects on N uptake and remobilization during regrowth of Italian ryegrass (Lolium multiflorum)

Abstract The influence of P deficiency on the utilization of two sources of N, mineral N (exogenous N) and reserved N (endogenous N), for regrowth of Italian ryegrass ( Lolium multiflorum ) was studied. P-sufficient (+P) or P-free (−P) nutrition solution was applied from 7 days before defoliation to 24 days of regrowth and the N flows derived from two different N sources within the plant were quantified by 15 N pulse-chase labeling. Shoot regrowth significantly reduced by 12 days of regrowth, while root growth was more in −P plants. Inorganic P (P i ) concentration was highly reduced by P deprivation more in the stubble and regrowing shoots and less in the roots. At defoliation, P deprivation had induced a higher accumulation for all N compounds in the stubble and for amino acids in the roots. The previously incorporated 15 N in stubble and roots as nitrate and amino acids was much decreased in −P plants especially for the first 6 days of regrowth. Total N content in the regrowing leaves was not significantly different between +P and −P plants, but percentage contribution of remobilized N for total leaf N formation was significantly higher in −P plants (78%) than in +P plants (69%) at 6 days of regrowth. From day 12, the utilization of both endogenous and exogenous N was apparently inhibited in −P plants.

Growth-inhibitory effects of a Bulnesia sarmienti aqueous extract on A549 Cells in vitro and S180 cells in vivo

The effects of Bulnesia sarmienti (BS) aqueous extract on the cell growth of A549 cell lines were investigated. BS has strong cytotoxic activity on the A549 cell lines (IC50; less than 100u2009μu2009g/mL) in MTT assay. HPLC confirmed that BS contains catechins as major compound. Cell cycle analysis by flow cytometry indicated that BS arrested the cell cycle in the sub-G1 phase. BS induced DNA fragmentation, and increased the expression of the p53 protein in immunoblot analysis. These results indicated that the anticancer effect of BS was mediated via the process of apoptosis and growth-inhibition.

Effect of proton beam irradiation on germination, seedling growth, and pasting properties of starch in rice

This study was carried out to determine the pretreatment effect of proton beam irradiation on germination and pasting properties of starches in two rices. Mature and healthy seeds irradiated with 10 doses (0, 50, 100, 200, 300, 400, 500, 600, 700, and 800 Gy) for determination of LD50 and characteristics of germination were recorded at 14 days after irradiation. The rice seeds irradiated with five doses (0, 50, 100, 200, and 300 Gy) were used to evaluate the irradiation effects of pasting properties of starches. It showed that a lower survival rate in germinated rice seeds was observed above 300 Gy showing 31 and 35% in Ilpum and Hanmaum, respectively. The higher plant height and root length were also recorded in 50 and 100 Gy. Amylose content in proton beam irradiated with 50, 100, 200, and 300 Gy was significantly decreased in two rice cultivars. Peak viscosity, hot peak viscosity, cooling peak viscosity, and setback viscosity decreased with increasing proton beam dose levels. The degree of crystallinity was significantly increased with increasing proton beam dose levels. Consequently, it might be deduced that proton beam irradiation causes changes of starch properties affecting crystalline regions of starch granules, especially at high dosage irradiation.

Fact-finding Survey on The Use of Paddy Field Herbicides at Farmer`s Level in Gyeongsangbuk-do Province

Field survey on the weed occurrence and the use of herbicides was carried out targeting 214 rice cultivating farmers at Gyeongsangbuk-do. 96.2% of farmers did machine planting in late May and this is 68.0% of total cultivating area. Spring plowing was first with 54.6%, followed by spring-fall and fall plowing with 24.8% and 15.0%, respectively. 75% of the farmers treated herbicide twice. 57.5% of them treated herbicide before transplanting and treated at post-emergence again. In case of only application, 84% of the farmers treated herbicide before transplanting. Twenty-three species were occurred at Gyeongsangbuk-do and Echinochloa spp. was the most dominant with 20.8%, Sagittaria trifolia was second with 10.4%, followed by Monochoria vaginalis and Sagittaria pygmaea with 9.9% and 9.7%, respectively. Sagittaria pygmaea was the most difficult to control followed by Echinochloa spp., M. vaginalis, and S. trifolia.

Physicochemical Properties of Starch in Water Chestnut (Eleocharis kuroguwai Ohwi)

The physicochemical properties of tuber starch in water chestnut have been studied. Peak viscosity, hot paste viscosity and cooling peak viscosity were 5679, 3146 and 4262 RVU, respectively. In three transition parameters, onset temperature (T o ), peak temperature (T p ), and conclusion temperature (T c ) were 64.1, 68.5 and 72.3℃, respectively. Gelatinization enthalpy (ΔH gel) was 4.48 J/g. A-type starch has a smaller proportion (11.4%) of short chains (DP≥12) and a larger proportion (57.2%) of short chains (13≤DP≤24). The tuber starch of water chestnut displayed an A-type X-ray diffraction pattern showing a strong diffraction peak at 2Θ values of 15.18°, 17.13°, and 23.1°, and a weak peak at 2Θ values of 18.1°, 20.06°, and 26.69°. Their crystallinity was 28.6% and the mean starch granule size was 21.5 μm.