Heat shock pretreatment, dark culture period and washing medium could have marked effects on microspore embryogenesis. A heat shock pretreatment of microspores at 32.5°C for 48 hours gave high production rate of microspore-derived embryo (MDE) when compare to shorter and longer period. The yield of MDE increased significantly when microspore cultured for 15 days at 25℃ in dark condition followed by heat shock pretreatment. MDE were browned and lost vitality when dark treatment period extended longer than 15 days. This is caused by an insufficient oxygen and light for growing embryo which already formed during dark treatment period. The vitality of a microspore isolated from flower bud stored at 4℃ become decreased at the very first day and the vitality of microspore stored at 4℃ in the form of flower bud itself become decreased from the 5th day after storage. This shows the possibility of getting a certain period of storage for a suitable flower bud in MDE formation. The yield of MDE was most effective when isolated microspore was had with MS medium compared to B-5 and NLN medium and also showed most effective result with sucrose 130 g􀂂L-1 in additional sucrose concentration. The above result is thought to be very useful for the development of a new cultivar of radish and other many crops including Brassica using haploid breeding technology.

“Surabyeo” is a new japonica rice cultivar developed from a backcrossed combination between the F1 of “Suweon 345/ Kanto PL4” and “Suweon 345” of lodging tolerant, semi-dwarf, high-quality rice line by the rice breeding team of National Crop Experiment St