铅胁迫对杨梅生理特性的影响

通过水培试验，研究了不同浓度的铅胁迫对杨梅（Myrica rubra Sieb. et Zucc.）叶片的叶绿素含量、可溶性蛋白质含量、可溶性糖含量、超氧化物歧化酶（SOD）活性、过氧化物酶（POD）活性、丙二醛（MDA）含量以及根系活力的影响。结果表明，在2 mmol·L^-1低铅条件下，杨梅叶片叶绿素含量和可溶性蛋白质含量在30 d内与对照相比无显著性差异；叶片可溶性糖和MDA含量在2 mmol·L^-1低铅处理第10 d即比对照显著增加；根系活力在2 mmol·L^-1低铅胁迫处理20 d后比对照显著降低；叶片SOD和POD活性在2 mmol·L^-1低铅胁迫下活性随着处理时间的延长而呈先升后降的变化趋势，在低铅处理第20 d SOD 和POD活性达到最大。在6 mmol·L^-1高铅胁迫下，杨梅叶片的叶绿素含量、可溶性蛋白质含量、SOD活性、POD活性、MDA含量以及根系活力均随着处理时间的延长而不断降低；而叶片可溶性糖含量在高铅处理30 d时比对照有所增加。综上所述，杨梅在低铅条件下可诱导活性氧清除系统以及叶片可溶性糖含量增加以减少由于铅胁迫带来的活性氧代谢失衡和缺水对植株的伤害。

Effects of Lead on Physiological Characteristics of Baylerry （Myrica rubra ） Seedlings

Phytoextraction is considered a cheap and green method to remove pollutants from the soil by plants. It was found that the lead （Pb） content in leaves of baylerry（Myrica rubra Sieb. et Zucc. ） seeding can reach 1 107 mg·L^-1 without observed injury. To understand the tolerance mechanism of baylerry to Pb, we investigated the effects of Pb treatments on the contents of chlorophyll, total soluble protein, soluble sugar and malondiadehyde（ MDA ）, root activity, activities of superoxide dismutase （ SOD ） and peroxidase （POD） in the leaves of baylerry seedlings in a period of 30 days. Three concentrations of lead, 2, 4, 6 mmol Pb^2·L^-1, were used in the treatments. Under the low concentration of Pb（2 mmol·L^-1 ）, the increasing soluble sugar and MDA content in leaves of Baylen-y seedlings were detected on the 10th day, while the decreasing root activity was detected on the 20th day. The SOD and POD activities in leaves of baylerry increased after the initiation of low Pb treatment, reached a peak on the 20th day, and then declined. The low Pd treatment showed no apparent effect on the contents of chlorophyll or total soluble protein. Under the high concentrations of Pb（6 mmol·L^-1 ）, the contents of chlorophyll, total soluble protein and malondiadehyde （MDA）, root activity, the activity of SOD and POD in the leaves of baylerry seedlings showed a decreasing trend during 30 days. In contrast, the contents of soluble sugar in the leaves showed an increase on the 30th day after the initiation of high Pb treatment. In conclusion, low Pb stress could induce antioxidant defense mechanism to prevent oxidative damage and increase soluble sugar contents to minimize the dehydration damage in Baylerry.