在超低温(-196℃) 条件下对中籼南京11号干种子进行γ射线辐射,再以修复抑制剂咖啡因(Caffeine) 液浸种,其M_1代损伤效应在本刊1988年第2期上已报道.本文报告M_2代突变效应,结果表明,在超低温下辐射使M_2代突变效率显著降低.用咖啡因溶液作为后处理浸种可显著提高M_2代的突变频率.因超低温下辐射在生长后期表现保护作用,提出提高辐射剂量,以提高诱变效率. Under the conditions of ultra-low temperature (-196 ℃), the seeds of mid-indica rice Nanjing No.11 were irradiated with γ-rays and then soaked with Caffeine solution, the effect of M_1 generation damage was reported in the 2nd issue, 1988 Reported in this paper M_2 generation mutation effect, the results showed that in the low temperature radiation M_2 generation mutation efficiency significantly reduced with caffeine solution as a post-treatment soaking can significantly increase the frequency of M_2 generation mutation due to ultra-low temperature radiation in the late growth performance protection Role, proposed to increase radiation dose, in order to improve the mutagenesis efficiency.