The direct use of mutation is a valuable approach to generate variability in crops. The electron beam, one of the ionizing radiations, has been applied to evaluate its effect on seed germination and early seedling growth of creeping bentgrass (Agrostis palustris Huds., cv Penn-A1). The mature dry seeds were irradiated with various electron beam energies (0.3, 1.0, 1.3, and 2 MeV) and current levels (0.03 and 0.06 mA). Although large variability was existed within each dose, distinct difference of germiability and seedling vigor were not found at 0.3 MeV / 0.03 mA and 0.3 MeV / 0.06 mA beam condition. However, 1.0 MeV / 0.06 mA application most effectively inhibited and retarded seed germination and most severely restricted cotyledon and root growth in early seedling growth. The direct use of electron beam would be a valuable supplementary approach to generate mutants suitable for breeding purposes.

Juhwangmi is a new sweetpotato variety developed from Mokpo Experiment Station, National Institute of Crop Sciencewasselected from seeds obtained by open polycros of SQ27 used as female in 1995, sedling and line selections were practiced from1996 to 1997,

This study was carried out to understand the genetic pattern of self-sterility, using a self-fertile variety Cheongyangnative 1 and nine self-sterile cultivars in cultivated boxthorn (Lycium chinense Mill., 2n=24). The inheritance of self-fertility (SF)wa

The rice straw managements are essential for maintaining soil fertility as well as reducing chemical fertilizer application in paddy field. A field experiment was conducted on moderately well draining alluvial paddy soil to investigate the decomposition pattern of rice straw. The mesh bags containing the rice straw harvested in the previous year were placed at soil surface and buried into around 10cm depth and recovered periodically for determining the straw decomposition. Pot experiments were conducted to investigate the fates of N released from 15 N-labeled rice straw under different levels of N fertilizer application. The overall decomposition patterns of rice straw were similar for the two incorporation depths in transplanted paddy field. The straw incorporated at transplanting date showed weight loss of about 50%, 70% and 90% after 2 months, 5 months, and 2 years, respectively. The decompositions of straw cell wall components showed somewhat different pattern. The decompositions of cellulose and silica were similar to that of dry weight while the decomposition of lignin was slower than that of cellulose and silica. N was released from rice straw 42% and 65 % of the initial N after one month and after five months, respectively. P release was faster than N release. Recoveries of rice straw-15 N by rice plants were 10.2, 13.4 and 14.9% in 0, 120 and 240 mg N pot-1 , respectively. Soil recoveries of rice straw 15 N were 17.3, 20.6 and 18.9% in 0, 120 and 240mg N pot-1 , respectively.