Knowledge of genetic diversity and of the genetic relationships among elite breeding materials has had a significant impact on the improvement of crops. In maize, this information is particularly useful in i) planning crosses for hybrid and line development, ii) in assigning lines to heterotic groups and iii) in plant variety protection. We have used the SSR technique to study the genetic diversity and genetic relationships among 76 Korean waxy corn accessions, representing a diverse collection from throughout Korea. Assessment of genetic diversity among members of this group was conducted using 30 microsatellite markers. Among these 30 microsatellite markers, we identified a total of 127 alleles (with an average of 4.2 and a range of between 2 and 9 alleles per locus). Gene diversity at these 30 microsatellite loci varied from 0.125 to 0.795 with an average of 0.507. The cluster tree generated with the described microsatellite markers recognized two major groups with 36.5% genetic similarity. Group I includes 63 inbred lines, with similarity coefficients of between 0.365 and 0.99. Group II includes 13 inbred lines, with similarity coefficients of between 0.45 and 0.85. The present study indicates that the 30 microsatellite loci chosen for this analysis are effective molecular markers for the assessment of genetic diversity and genetic relationships between Korean waxy corn accessions. Specifically, this study's assessment of genetic diversity and relationships between a set of 76 Korean waxy corn inbred lines will be helpful for such activities as planning crosses for hybrid and line development and association mapping analyses of maize breeding programs in Korea.

This study was done to understand the G x E interaction of rice blast reaction for Japonica high quality rice varieties and to observe blast pattern for high quality varieties. Twenty one percent of the total sum of squares (SST) in blast reaction data of high quality Japonica varieties is attributed to genotype (G) by environment (E) interaction variation. This portion of blast response is higher than 8～12% of G x E effect in blast severity data obtained from various ecotypes of rice varieties. Blast response scores obtained from high quality Japonica varieties group were more severely affected by environment condition than mixed groups with Japonica and Indica varieties. Interaction Principal Component Analysis (IPCA) scores obtained from AMMI analysis for the leaf blast response implied variation of G x E interaction. Correlation analysis suggested that IPCA1 was associated with latitude, maximum mean temperature, precipitation and mean cloud amount. IPCA2 was associated with mean relative humidity, and IPCA3 was associated with precipitation and minimum relative humidity. Pattern analysis generated nine genotype clusters according to blast reaction over 11 regions. Collectively, the A, B, C, and D groups were susceptible to rice blast, where as the E, F, G, H, and I groups were relatively resistant to rice blast through multi-location blast nursery test. Relationship between the identified genes of high quality varieties and blast scores at each test site in the level of group could be analyzed based on the results from G x E Interaction analysis.

Rice farmers can save labor and expenses by using expanded rice husk (ERH) as a seedling medium since ERH is lighter and cheaper than other commercial seedling media (CSM). This study was carried out to develop a method for rice seedling cultivation using ERH as a seedling medium. It is suggested that a mixture of 60~% of ERH and 40~% of a CSM could be used as a seedling medium; the planting densities would be 240g per tray for infant seedlings and 200 g for young seedlings; and nitrogen (N) would be applied at a rate of 1g per tray for infant seedlings prior to planting and 2g per tray for young seedlings with division. Great care should be taken to use CO(NH2)2 as an N-source fertilizer. These results would lay a foundation for the rice seedling cultivation with ERH as a medium.

A single cross hybrid, 'Heugjeomchal', is a white and black bicolor waxy corn (Zea mays L.) developed by the Maize Experiment Station (MES), Gangwondo Agricultural Research and Extension Services (GARES) in Hongcheon in 2000. 'Heugjeomchal' was made by cr