"Oraebyeo" is mutation of a high quality japonica cultivar, Ilpumbyeoa new japonica rice(Oriza sativa L.) cultivar developed from by N-methyl-N-nitrosourea(MNU) treatment on fertilized egg cell by the rice breeding team of Gangwon Provincial Agricultural Res. & Ext. Service in 2006. This variety heads 20 days earlier than Ilpumbyeo and similar to that of Odaebyeo an early maturing leading cultivar of northern plain area of Korea. Compared with Odaebyeo has a good semi-erect plant type with lodging tolerance due to much shortened plant hight(l2cm shorter than Odaebyeo). Oraebyeo has similar panicle number with Odaebye where as it has more spikelets per panicle. However, this variety less the ratio of ripened grains and 1,000 grain weight than those of Odaebyeo. The yield performance of this cultivar in milled rice was about 5.09MT/ha in local adaptability test conducted for three years 2002-2004 and 5.51MT/ha in the demonstration plot of farmer's field.

Sanggolbyeo is a new japonica rice cultivar developed from Ilpumbyeo mutation lines by N-methyl-N-nitrosourea(MNU) treatment on fertilized egg cell by the rice breeding team of Gangwon Provincial Agricultural Res.& Ext. Service in 2006. This cultivar has about 135 days growth duration from transplanting to harvesting. Sanggolbyeo has short and round grain and non-glutinous endosperm with very low phytate content, below 50% of Ilpumbyeo, implying it could help men to absorb Calcium from rice. This cultivar shows midium diseases tolerance to leaf blast, bacterial blight, virus and insect pest. The milled rice yield of Sanggolbyeo is about 4.98 MT/ha at ordinary transplanting culture in the local adaptability test. Sanggolbyeo would be adaptable for the mid-northern plain areas of Korea.

The effects of the transferred green rice leafhopper (GRH) resistant gene on yield and grain quality were analyzed by using 7 near-isogenic lines (NILs) with introgressed GRH resistance gene in rice cultivar "Ilpumbyeo". The genotype analysis using SSR markers indicated that all NILs were recovered more than 95% as compared with recurrent parent "Ilpumbyeo". All NILs showed no significant differences compared to recurrent parent for grain yield. No significant differences were observed between NILs and their recurrent parent for physicochemical traits (protein content, amylose content and alkali spreading value) and eating quality. But there were significant differences for appearance of brown and milled rice and pasting properties between some NILs and their recurrent parent. It means that these grain appearance and pasting traits of NILs were very similar or more improved compared to recurrent parent "Ilpumbyeo". Thus, it could be possible to develop GRH resistant variety with high ,quality in segregating populations.

Phenotypes of panicle, hull and seed of mutant rice (Oryza sativa L.) were characterized. Panicle mutants were classified in 4 groups with their internode length of main rachis, primary rachis, secondary rachis and pedicel. Hull and seed mutants were grouped into 12 based on their mutant characters in shape, size and color of seeds. These natural and spontaneous mutant collections showed distinct phenotypes to wild type rice. This might be useful for the identification of the functions of genetic factors in the Mendelian inheritance.