辐射对蓖麻种子生长及生理指标的影响

通过研究高剂量率（10Gy／min）不同剂量^60Coγ射线辐照（200-1500Gy）对蓖麻种子萌发、生长、田间出苗及相关生理指标的影响，结果发现：辐射剂量对种子最终发芽率影响不明显，但对田间出苗率、胚根长度及幼苗高度存在极显著影响，1000Gy以上剂量时，种子及幼苗的生长明显受到抑制，胚根缩短变粗，幼苗高度明显下降，田间出苗率也急剧下降；随着辐射剂量的增加，MDA含量、SOD活性及POD活性都呈先升后降趋势，在1000Gy时，达到最高峰值。根据田间出苗率进行回归分析，得出高剂量率辐射诱变的半致死剂量和临界剂量分别为1048．83Gy和1134．21Gy。结合种子萌发、幼苗生长及实际出苗情况考虑，初步认为：高剂量率条件下（10Gy／min），“淄蓖5号”干种子的”Coγ辐射诱变以900Gy左右剂量（大于800Gy，小于1000Gy）较为适宜。

Effects of ^60Coγ-rays Irradiation on Seed Growth and Physiological Indexes of Castor Bean

The seeds of castor bean were used to investigate the effects of different doses of ^60Coγ-rays irradiation （200- 1 500 Gy） with 10 Gy/min high irradiation rate on seed germination, seedling emergence, seedling growth and physiological characteristics. The results showed that there were no obvious discrepancies in the last seed germination rate among the eight different dosages, however, the percentage of seedling emergence, radicle length and seedling height were signifi- cantly influenced by irradiation dosage. When the irradiation dosage was above I 000 Gy, the growth of seeds and seed- lings were distinctly suppressed, radicle became short and thick, seedling height decreased markedly, and the rate of seedling emergence also dramatically reduced. With the gradual enhancement of irradiation dosage, the content of malondialdehyde （MDA）, the activities of superoxide dismutase （SOD） and peroxidase （POD） were increased at first, and then declined, and the largest value was presented at the 1 000 Gy irradiation. The regression analysis between the seedling e- mergence rate and the irradiation dosage showed that the half lethal dosage （ LD50 ） and the critical dosage （ LD40 ） were 1 048. 83 Gy and 1 134. 21 Gy respectively. Combining with the consideration of seed germination, seedling growth and fac- tual seedling emergence, the appropriate dosage of ^60Coγ-rays irradiation-induced mutation for ＇ ZibiS＇ castor bean seeds was about 900 Gy （more than 800 Gy and less than 1 000 Gy） with 10 Gy/min irradiation rate.