Cell adhesion is used as a parameter to evaluate the biocompatibility of dental implant and also affected by the surface form of dental implant. Most study have showed different cell reaction by the composition and the surface morphology of implant. Therefore it is thought that the osteoblastic activity would be affected by the surface roughness and composition of implants. This study was performed to evaluate the biological activity and morphological change of normal human osteoblastic cells(NHost) depending on the variations of implant surfaces. We used grade 2 titanium disks which were being air-blasted with TiO2 50 ㎛, 110 ㎛, 250 ㎛ powder by 3psi compressed air and non-blasted as control. We evaluated and compared morphologic change, adhesion assay, and Ca, P, ALP concentration of NHost in vitro. The obtained results were as follows. 1. In the growth curve, although the growth of experimental groups were lower than that of the group of NHost only, there was no significant difference between each groups. 2. Inverted microscopic findings showed NHosts in early stage of each group were adherant perpendicular to the titanium disk and the multilayered NHosts were attached with various directions after 4 weeks. 3. Scanning electron microscopic(SEM) features showed that NHosts in all groups seemed to be attached multilayered and connected with each process after 2 weeks. 4. NHosts' processes were found by the SEM after one day culture. The cell adhesion of experiment group was higher than that of control group. 110 ㎛(the 3rd group) showed prominant process of NHost on the titanium disk surface. 5. Although the concentrations of Ca, P and ALP were gradually reduced, ANOVA analysis of each groups were partially different, and ANOVA analysis of 4th group were significantly different with others. From the aboving results, NHosts cultured on the titanium disks showed similar morphological change and cell proliferation. There were partially differences in each group except the 4th group, and the 4th group were significantly different with other's in biological activity. We thought that biological activity and adhesion of NHost cell on titanium had been affected by the variation of the titanium surface roughness.

Inweolbyeo is a japonica rice (Oryza sativa L.) variety developed by Unbong Substation, National Honam Agricultural Experiment Station, RDA in 1998. It was selected from progenies from a cross between Fukei 127 and Unbongbyeo by pedigree breeding method.

“Sobibyeo” is a new japonica rice cultivar developed from a cross betw een Hwayeongbyeo and YR13604Acp22 line by the rice breeding team of National Honam Agricultural Experiment Station (NHAES), RDA, in 1999. This cultivar has a large grain and about 119

This study was carried out to investigate the ef f ect of nitrogen level and planting density on panicle traits and to exam -ine the desirable panicle structure for better ripening and high yielding in rice. Four dif f erent panicle types of rice varietie

The object of this study was to determine the difference of the time course changes of transpiration, diffusion resistance and photosynthetic rate of rice at several different growth stages subjected to soil moisture stress (SMS) and recovery by irrigation. A japonica rice cultivar 'Dongjinbyeo', was grown under flooded condition in a plastic container filled with silty loam soil. At 5 main growth stages, the container was treated by SMS until initial wilting point (IWP) and then reirrigated. The duration of SMS until IWP were the longest, 13 days for tillering stage, and the shortest, 7 days for panicle initiation and meiosis stage. The transpiration rate rapidly decreased during SMS and the transpiration rate at IWP of the stressed plant showed 10∼20% compared with control, and the transpiration rate of stressed plant at most growth stages also recovered rapidly after irrigation and then reached 100% of control within a week. The shoot photosynthetic rate in all growth stages rapidly decreased by SMS, and the rates at IWP of stressed plants were de-creased nearly to 0%, beside the treatment at tillering stage. The recovery degree of photosynthetic rate by irrigation ranged from 20 to 90%, showed higher at early growth stages of SMS treatment than that of later stages. At all growth stages the leaf diffusion resistance of stressed plants was over 3 times that of the control resulting from a rapid increase at 3 to 5 days after draining for SMS, and showed quick recovery by irrigation within 3 days after drainage. The above physiological parameters changed in close relation with the decrease of the soil matric potential after SMS. These results indicate that at all main growth stages of rice plants the transpiration and photosynthesis reduction by stomatal closure reponded sensitively to the first stage of SMS closely related with decrease of soil water potential, while those recovery pattern and recovered degree by irrigation are little different by growth stage of rice.

To examine the seedling stand and growth as affected by early seeding dates of dry direct seeded rice in the Honam plain area of Korea, Dongjinbyeo was seeded at six seeding dates from early March to late April in rice fields of silty loam soil(Jeonbuk series) at the National Honam Agricultural Experiment Station (NHAES) for two years, 1996 and 1998. Seedling stand decreased slightly. with an early seeding date, but it produced more than the optimum seedling number except for the seeding of 25 March in 1996. Days to emergence was significantly longer, as seeding date was earlier, and days to emergence by early seeding was shortened only by 8 days because the mean air temperature was lower in 1996 than average, while in 1998, the reduction effect was nine to twenty five days because the mean air temperature was higher than average. In early seeding, various weeds occurred at the emergence date of rice and dominant weeds were Alopecurus aequailis, Ludwigia prostata and Rorippa islandica. NH4 + -N content in the soil at the 5th leaf stage and maximum tillering stage were lower, as the seeding date was earlier when nitrogen was split applied as basal and top dressed in 1996, while it was not significantly different among seeding dates when nitrogen was intensively applied as a top dressing in 1998. Tiller number at the maximum tillering stage and panicle number/m2 were more, as seeding date was earlier in 1996, while it was not different in 1998. Filled grain rate and 1,000 grain weight was not different among the seeding dates. Milled rice yield was significantly decreased in the seeding before the middle of March, but in the seeding after late March, it was not varied when compared with the normal seeding date in 1996, while in 1998, there was no difference among seeding dates. From the above results, in consideration of seedling stand, weed occurance, rice growth and milled rice yield, the critical optimum early seeding time in the southern plain area may lie in early April. But it was suggested that when soil moisture is proper for seeding practices, seeding amount is increased and nitrogen is applied after plumule emergence of rice, milled rice yield may not be reduced in the seeding of middle or late March, compared with the seeding in April.l.