太空飞行对玉米种子的生物学效应

本试验对５００多粒太空飞行后回收的玉米种子的生长发育进行了观察。种子置于一个长期辐射照装置（ＩＤＥＦ）内，在低地球轨道飞行了６９月。结果表明，太空环境对玉米种子发芽率无影响。当代植株中发现矮化，株色和叶鞘色变化，叶片出现黄或白色条纹等形态变异。以叶片黄，白条纹出现率为变异率的指标，与加速重离子束对同一玉米品种辐照获得的数据相对比，可估算出种子在太空飞行期间受到辐射的平均剂量相当于６３５ｃＧｙ的γ射

BIOLOGICAL EFFECTS OF SPACE FLIGHT ON CORN SEEDS

The growth and development of more than 500 corn seeds flown on Long Duration EXposure Facility(LDEF),which 69 months in low-Earth orbit, were studied.The results of investigation indicated that the envionmental condition in spaee had no obvious effects on seed germination.Most of the germinated seeds from LDEF fight grew into plants normally,but with average height shorter than that of control.Variations,including White-yellow stripes on leaves,dwarfing,change of leaf sheath color or plant col-or,were observed in plants developed from these seeds.When the ferquency of white-yellow stripe formation was used as the endpoint and compared with data from ground based studies,the dose to which corn seeds might be exposed during this flight was estimated to be equiv alent to 635 cGy of gamma rays.Seeds from different holdere gave significant differentvariation frequency. White-yellow stripes on leaves were also found in some of the inbred progenies from plants displayed variation,Electron microscopy studies showed that the damage of chroloplast development in the white-yellow stripes on leaves was Similar between seeds flown on LDEF and that irradiated by accelerated heavy ions on ground.