重金属铜铅对2种凤尾鸡冠花品种种子萌发的影响

Effects of Cu and PbStress on Seed Germination of Two Varieties of Cockscombs

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。

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.