^(60)Co-γ辐射对扁穗雀麦种子萌发及其幼苗生长的影响

Effects of ^(60)Co-γ radiation on the seed germination and seedling growth of Bromus catharticus

为探究不同^(60)Co-γ辐射剂量对扁穗雀麦(Bromus catharticus)种子萌发及其幼苗生长的影响,本研究比较和分析了不同辐射剂量^(60)Co-γ(0、50、100、150、200、250、300 Gy)处理下种子萌发指标、幼苗根系和叶片形态指标及幼苗生理生化指标。结果表明:在种子萌发和幼苗形态指标方面,种子发芽势随辐射剂量的上升呈现出先升高后降低的趋势,并在50 Gy处理下达到最大值,为32%。除50 Gy处理下的种子萌发率、幼苗苗高和根长与50和100 Gy处理下的幼苗叶长略高于对照(0)外,其余各剂量的上述指标均低于对照。除150 Gy处理下幼苗叶面积小于对照外,其余处理下叶宽、茎粗和叶面积均高于对照。幼苗根系表面积和体积与辐射剂量的变化呈反比。根系平均直径在^(60)Co-γ辐射处理下与对照间无明显差异(P>0.05)。当辐射剂量为250和300 Gy时,幼苗全部死亡。在幼苗生理生化指标方面,幼苗脯氨酸(proline,Pro)、丙二醛(malondialdehyde,MDA)和叶绿素(chlorophyll,Chl)含量以及过氧化氢酶(catalase,CAT)和超氧化物歧化酶(superoxide dismutase,SOD)活性均受^(60)Co-γ辐射的显著影响(P<0.05),并随着辐射剂量的上升呈现出先升高后降低的趋势。隶属函数综合评价表明,^(60)Co-γ诱变处理后的种子萌发和幼苗生长状况在辐射剂量为50和100 Gy时综合表现最优。经线性回归计算,扁穗雀麦种子在^(60)Co-γ辐射处理下的半致死剂量约为224 Gy。本研究结果可为创制扁穗雀麦新种质提供技术参考。

In order to investigate the effects of different doses of ^(60)Co-γon the seeds and seedlings of Bromus catharticus,we compared the seed germination index,root morphology index,seedling morphology,and physiological index of B.catharticus treated with different doses of ^(60)Co-γ(0,50,100,150,200,250,and 300 Gy).The main results obtained were as follows.In terms of seed germination and seedling morphological indices,we found that in response to an increase in radiation dose,the germination potential of seeds showed a trend of initial increase and subsequent decline,reaching a maximum value of 32%at a radiation dose of 50 Gy.In addition,percentage B.catharticus seed germination and seedling height and root length at 50 Gy radiation,and seedling leaf length at 50 and 100 Gy radiation,were slightly higher those of the control.In contrast,at all other radiation doses assessed,these indices were lower than those of the control group.Although the leaf width and stem diameter of seedlings exposed to 150 Gy radiation were higher than those of the control seedlings,the leaf area of seedlings at this dose was smaller than that of control seedlings.The root surface area and volume of seedlings were found to be inversely proportional to the radiation dose,although there were no significant differences in mean root diameter between seedlings subjected to ^(60)Co-γradiation and control treatments(P>0.05).At the higher radiation doses of 250 and 300 Gy,seedling mortality approached 100%.With respect to the physiological and biochemical indices of seedlings,the contents of proline(Pro),malondialdehyde(MDA),and chlorophyll(Chl),as well as the activities of catalase(CAT)and superoxide dismutase(SOD),were significantly affected by exposure to ^(60)Co-γradiation(P<0.05),showing a trend of initial increase and subsequent decline in response to exposure to an increasing radiation dose.Membership function analysis indicated that optimal seed germination and seedling growth were obtained in response to ^(60)Co-γradiation mutagenesis at doses of 50 and 100 Gy.Moreover,the semi-lethal dose of ^(60)Co-γradiation for B.catharticus was calculated to be approximately 224 Gy.The results obtained in this study will provide a theoretical basis and technical guidance for the innovative development of B.catharticus germplasm resources.