铀胁迫对5种牧草种子萌发的影响

Effect of the uranium stress on the seed germination of the five forage species

为进一步探究放射性重金属铀污染环境对植物种子萌芽及生长所产生的迫害,根据我国铀矿冶废水中铀的质量浓度(5 mg/L)选择不同质量浓度(0、1 mg/L、5 mg/L、10 mg/L、15 mg/L、20 mg/L)的铀溶液进行试验,用以胁迫5种1年生牧草(三叶草、苜蓿草、黑麦草、高丹草和苏丹草)种子,同时观察记录各自的萌发状况(发芽数和第7 d幼苗生长长度),计算其发芽率、发芽势、发芽指数(GI)、活力指数(VI)及耐性指数,并与对照组进行量化指标比较。最后比较各牧草种子所受到的危害并做出评价。结果表明:对于不同程度的铀污染,多数植物表现为低质量浓度促进其种子萌发,高质量浓度则严重抑制甚至致死。对于三叶草、苜蓿草和黑麦草种子,低质量浓度(1 mg/L)铀溶液促进种子的萌发,质量浓度升高则为抑制,其中黑麦草表现稍异常,质量浓度为5 mg/L时对种子萌发有促进作用,使最终发芽率较对照提升14%;对于高丹草,低质量浓度(5 mg/L)时促进种子萌发,而在质量浓度稍低于或超过5 mg/L时表现出明显的抑制现象,各指标低于对照13%左右;苏丹草则仅呈现抑制现象,铀质量浓度为5mg/L时抑制现象稍轻,最终发芽率较对照组仅降4%,小于或大于5mg/L时均受抑制,且质量浓度越高抑制现象越明显,最终发芽率最高仅28%。

To further explore the damage caused by the heavy radioactive metal（ uranium） contaminated environment to the germination of the plant seeds and the growth of newly prepared seedlings,the paper has chosen different concentrations of uranium solution（ 0,1 mg / L,5 mg / L,10 mg / L,15 mg / L,20 mg / L） based on the general content in the uranium mining sewage of 5 mg / L to affect the above-said five annual forage seeds,that is,those of Trifolium repens,Medicago sativa L.,Lolium perenne,Sorghum and Sorghum sudanense（ Piper） Stapf. In our research,we have been keeping on the observation and recording of the germination conditions of each group（ germination number and seedlings growth on the seventh day）. At the same time,we have made quantitative comparison with those of the control group. As a result,we have found that the damage thateach forage seed has its own individual germination rate,energy,index,vigor index and the tolerance index. Moreover,we have also discovered that the germination of the three forage seeds（ Trifolium repens,Medicago sativa L. and Lolium perenne） can be made promoted in the low uranium concentration of 1 mg / L,though inhibited by raising the concentration of U（ VI） except for the Lolium perenne seeds,whose final germination rate can only be made promoted by 14% as compared with the control group in the concentration of 5 mg / L,whereas the Sorghum seeds germination can be pushed up by the uranium concentration of 5 mg / L. because it tends to be inhibited obviously when the concentration turns to be lower or higher than 5mg / L,which make all its indicators less than 13% of the control group. On the contrary,when the uranium concentration stays at5 mg / L,the seeds of Sorghum sudanense（ Piper） Stapf proves to be inhibited just slightly,with its final germination only reduced by 4%. However,if the concentration tends to be lower or higher than 5 mg / L,it would also be inhibited,with the inhibition trend being more obvious in a higher concentration solution,when the highest final germination rate turns to be as high as up to 28%. Therefore,it can be concluded that faced with the uranium pollutants at different levels,it would be possible for the most seeds to be promoted in a lower concentration in germination were,and even to be inhibited or caused to die at high concentrations.