This study was conducted to clarify the relation of the species of genus Sorbus in Korea based on multivariate analysis for the morphological characteristics and DNA polymorphism. Twenty-eight quantitative characters were assessed and analyzed by the principal component analysis and UPGMA cluster analysis. From the principal component analysis of 28 quantitative characters, three principal components (PC’s) explained the variation of inter-specific relations among the genus Sorbus. The first PC’s explained 58.95% of the variation with the Eigenvalue of 16.5, and the second and third PC’s showed the Eigenvalue of 8.3 and 3.1 and explained 88.74% and 100.0% of the variation, respectively. Especially, the first PC’s was related in order of the fruit width (FW) and length of terminal leaflet (LTL), petal length (PL), width of terminal leaflet (WTL), and diameter of winter bud (DWB). The second and third PC’s were involved in order of the No. of leaflet (NL), No. of fruit per fruiting lateral (NFL), length of upper rachis (LUR), and diameter of rachis (DR), No. of pistil (NP), respectively. Cluster analysis using them UPGMA method based on the principal components of four species of the genus Sorbus divided into two groups. Group Ⅰ comprises Sorbus commixta and S. sambucifolia var. pseudogracilis, and Group Ⅱ consists of S. amurensis and S. aucuparia. The pattern of DNA polymorphism of the 56 inter-simple sequence repeat (ISSR) markers revealed that different taxa shared different sets of bands, and DNA analysis is useful for taxonomic study on the genus Sorbus.

“Jinpumbyeo” is a new japonica rice cultivar developed from a cross between lodging tolerant semi-dwarf plant type, SR14703-60-5-GH1 and high eating quality cultivar Suweon353 by the rice breeding team of National Crop Experiment Station, RDA made in 1987

Rice plants segregating for opaque endosperm were selected and tested in every generation from F₅ to F₉ of a CB243/IR50 cross. Six near isogenic lines(NIL_s) showing difference in opaqueness, of which three lines have opaqu

Nineteen japonica and Tongil-type rices were selected from seventy nine Korean and Japanese rice cultivars grown in 1989 based on the water uptake behavior of milled rice under the room temperature and boiling conditions. The selected rice cultivars were investigated for water absorbability and some physicochemical characteristics of milled rice, proper water amount for cooking and sensory evaluation of cooked rice. The relationships among the tested grain properties were also examined. The highest varietal variation of water uptake rate was observed at twenty minutes after soaking in water. The maximum water uptake of milled rices at room temperature occurred mostly at about eighty minutes after soaking in water. Newly harvested rices showed a significantly lower water uptake rate of milled rice at 20 minutes after soaking, a relatively higher maximum water absorption ratio under the room temperature, and the less water uptake and volume expansion of boiled rice compared with the one-year old rice samples. The water uptake rate and the maximum water absorption ratio showed significantly negative correlations with the K/Mg ratio and alkali digestion value(ADV) of milled rice. The rice materials showing the higher amount of hot water absorption exhibited the larger volume expansion of cooked rice. The harder rices with lower moisture content revealed the higher rate of water uptake at twenty minutes after soaking and the higher ratio of maximum water uptake under the room temperature condition. These water uptake characteristics were not associated with the protein and amylose contents of milled rice ansd the palatability of cooked rice. The water/rice ratio(in w/w basis) for optimum cooking was averaged to 1.52 in dry milled rices (12% wet basis) with varietal range from 1.45 to 1.61 and the expansion ratio of milled rice after proper boiling was averaged to 2.63(in v/v basis). The water amount needed for optimum cooking was the lowest in Cheongcheongbyeo (Tongil-type rice) and the highest in Jinbubyeo, and the amount could be estimated with about 70% fittness by the multiple regression formula based on some water uptake characteristics, ADV and amylose content of milled rice as the independent variables. Nineteen rice cultivars were classified into seven groups based on scatter diagram projected by principal component analysis using eight properties related to water uptake and gelatinization of milled 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.