Pb胁迫条件下狭叶香蒲种子的萌发特性及其幼苗的生理响应

对0、30、150、300、450和600μmol·L-1Pb胁迫条件下狭叶香蒲（TyphaangustifoliaLinn.）种子的萌发特性进行了研究，并分析了0、450、900、1800和2700μmol·L-1Pb胁迫对狭叶香蒲幼苗叶片及根系中部分生理生化指标的影响。结果表明：随Pb浓度提高，狭叶香蒲种子的发芽率、发芽势、发芽指数和活力指数以及下胚轴长度均逐渐下降且低于对照，而其下胚轴长度抑制指数则逐渐增大，但在30μmol·L-1Pb胁迫条件下各项萌发指标均与对照无显著差异。叶片叶绿素a、叶绿素b及总叶绿素含量随Pb浓度提高呈逐渐下降趋势，但在450和900μmol·L-1Pb胁迫条件下与对照无显著差异，而在1800和2700μmol·L-1Pb胁迫条件下显著低于对照。在Pb胁迫条件下叶片和根中SOD活性均显著高于对照但变化趋势不同；随Pb浓度提高，叶片SOD活性呈波动但整体上升的趋势，而根中SOD活性则呈逐渐降低的趋势。叶片和根中POD活性均随Pb浓度提高呈持续上升的趋势，其中，在450和900μmol·L-1Pb胁迫条件下叶片的POD活性低于对照、根的POD活性高于对照，但均与对照无显著差异；而在1800和2700μmol·L-1Pb胁迫条件下叶片和根的POD活性均显著高于对照。在Pb胁迫条件下叶片和根中AsA和MDA含量均高于对照。随Pb浓度提高，叶片的AsA含量总体上逐渐增加但在450和900μmol·L-1Pb胁迫条件下与对照无显著差异；而根的AsA含量则呈先增加后降低的趋势且均与对照差异显著。随Pb浓度提高，叶片的MDA含量先增后降但均与对照无显著差异；而根的MDA含量呈“高-低-高”的波动趋势且仅在450μmol·L-1Pb胁迫条件下与对照差异显著。综合分析结果显示：狭叶香蒲幼苗根系对Pb胁迫的敏感性可能强于叶片；狭叶香蒲种子可在轻度Pb污染水体中萌发和生长；其幼苗对Pb胁迫具有一定的耐性，可用于中度Pb污染水体的修复。

Seed germination characteristics and seedling physiological response of Typha angustifolia under Pb stress

Seed germination characteristics of Typha angustifolia Linn. under Pb stress with concentrations of 0, 30, 150, 300, 450 and 600 μmol·L-1 were studied, and effects of Pb stress with concentrations of 0, 450, 900, 1 800 and 2 700 μmol·L-1 on some physiological and biochemical indexes in leaf and root of seedling were analyzed. The results show that with rising of Pb concentration, germination rate, germination energy, germination index and vigor index and hypocotyl length of T.angustifolia seed all decrease gradually and are lower than those of the control, while inhibition index of hypocotyl length increases gradually, but under 30 μmol·L-1 Pb stress, there is no significant difference in each germination index with the control. Contents of chla, chlb and total chlorophyll in leaf appear the trend of decreasing gradually with rising of Pb concentration, but those under 450 and 900 μmol·L-1 Pb stress have no significant differences comparing with those of the control, while those under 1 800 and 2 700 μmol·L-1 Pb stress are significantly lower than those of the control. Under Pb stress, SOD activity in leaf and root is significantly higher than that of the control but their variation trend is different. With rising of Pb concentration, SOD activity in leaf appears a fluctuant but totally increasing trend, while that in root appears a gradually decreasing trend. POD activity in leaf and root appears a continually increasing trend with rising of Pb concentration. In which, under 450 and 900 μmol·L-1 Pb stress, POD activity in leaf is lower and that in root is higher than that of the control but with no significant difference to the control, while POD activity in leaf and root under 1 800 and 2 700 μmol·L-1 Pb stress is significantly higher than that of the control. Under Pb stress, contents of AsA and MDA in leaf and root are higher than those of the control. With rising of Pb concentration, overall, AsA content in leaf increases gradually but that under 450 and 900 μmol · L-1 Pb stress has no signif