重金属铜铅对2种凤尾鸡冠花品种种子萌发的影响

以‘和服’、‘红塔山’2个品种凤尾鸡冠花(Celosia plumose‘Kimono’;Celosia plumose‘Hongta’)种子为研究对象,经2种重金属(Cu2+、Pb2+)不同质量浓度梯度(50、200、350、500 mg/L)的处理,测定各处理种子发芽率、发芽势、发芽指数、胚根长度,计算种子耐金属胁迫的适宜重金属质量浓度、半致死重金属质量浓度、极限重金属质量浓度;分析2种重金属胁迫对2种凤尾鸡冠花种子萌发的影响、凤尾鸡冠花适应重金属质量浓度范围。结果表明:(1)随着处理液Cu2+质量浓度的升高,凤尾鸡冠花的发芽率、发芽势、发芽指数逐渐呈降低趋势。处理液质量浓度为50 mg/L时,Pb2+的胁迫对凤尾鸡冠花种子的各项萌发指标有所升高,表现为低促高抑;Cu2+胁迫对凤尾鸡冠花种子的毒害作用较Pb2+更强。(2)在处理液质量浓度为500 mg/L时,经Cu2+、Pb2+胁迫的凤尾鸡冠花种子仍分别有60%、70%以上的发芽率,说明凤尾鸡冠花种子对2种重金属具有一定耐受性,‘红塔山’种子的耐受性略高于‘和服’种子的耐受性。(3)重金属Cu2+对种子胚根的抑制作用十分显著。处理液质量浓度为50 mg/L时,Cu2+胁迫使凤尾鸡冠花根尖受害显著。低质量浓度Pb2+胁迫时凤尾鸡冠花胚根子叶发育正常;处理液质量浓度为200 mg/L至更高,Pb2+胁迫时胚根的生长显著受到抑制,出现胚根停止生长、变黑、腐烂的现象。Cu2+对2种凤尾鸡冠花种子萌发的抑制较强,Pb2+在低质量浓度时表现出促进发芽的作用。

Effects of Cu2+ and Pb2+Stress on Seed Germination of Two Varieties of Cockscombs

We took the seeds of two varieties of cockscombs in ‘kimono’ and ‘Hongtashan’ as the research object to study the effects of two heavy metals Cu2+ and Pb2+ stress on the seed germination, and to investigate the adaptation range of cockscomb as potential heavy metal resistant plant. With the increase of Cu2+ concentration, the germination rate, germination vigor and germination index of cockscomb gradually decreased. Under the stress of 50 mg/L Pb2+, the germination indexes of the cockscomb seeds rose, showing that low concentration promotion and high concentration suppression. At the same concentration, Cu2+ stress is more toxic to the seeds than Pb2+. Cockscombs still have more than 60%-70% germination rate under 500 mg/L Cu2+ and Pb2+ stress. The results indicate that the seeds of cockscomb have a certain tolerance to two heavy metals mentioned above. The tolerance of ‘Hongtashan’ seeds is slightly higher than that of ‘Kimono’. The inhibitory effect of Cu2+ on seed radicle is very significant, and under 50 mg/L Cu2+ stress in particular, the root tip of cockscomb was damaged. The cotyledons and radicle of cockscomb developed normally under the stress of low concentration of Pb2+, and the growth of the radicle was significantly inhibited under the stress of Pb2+ at 200 mg/L and higher, showed that the radicle stopped growing, blackened and rotted. Cu2+ has a strong inhibitory effect on the seed germination of the two cockscomb species, however, low concentrations of Pb2+ exhibits promoting germination.