铅胁迫对金盏银盘的生长及其根系耐性的影响

Lead Stress on Growth and Root Tolerance of Bidens biternata

通过水培模拟试验，在不同质量浓度（5、10、20、50、100mg·L^-1）铅（Pb）处理下，研究沼生药用植物金盏银盘（Bidensbiternata）地上部与根系生物量、根系长度和根活力、根系的耐性指数、体内Pb的质量分数与分布。结果表明：Pb处理质量浓度≤20mg·L^-1时，对金盏银盘生长有促进作用。随着Pb处理质量浓度的升高，生物量和根长开始下降，当Pb处理质量浓度达100mg·L^-1时，其生物量和根长均极显著降低（P〈0．01）。各质量浓度处理下的金盏银盘根系活力均低于对照，且都随着处理时间的延长而降低.随着Pb处理质量浓度的升高，金盏银盘体内各部位Pb质量分数基本表现为先升高后降低，其中叶和茎的Pb质量分数在Pb处理质量浓度为20mg·L^-1时达到最大；而根系在Ph处理质量浓度为10n培·L^-1时Pb质量分数最大，对铅的积累显著，质量分数高达2080．89mg·kg^-1。在Ph处理同质量浓度下，Pb在各部位的质量分数由大到小的顺序是根系、茎、叶。各处理质量浓度下的转移系数均小于0．1。在Pb处理质量浓度为10～20mg·L^-1时，金盏银盘的根系耐性指数大于1．0；随着Ph处理质量浓度的增加，根系耐性指数降低。

Shoot and root biomass, root length, root activity, root tolerance index, content and distribution of Pb in Bidens biter- nata were studied by hydroponics simulation test under different Pb concentrations（5, 10, 20, 50, 100 mg · L^-1）. Result indicated that Pb solution could promote B. biternata growth when Pb concentration was less than or equal to 20 mg · L^-1. Biomass and root length decreased with the increase of Pb concentration, and they decreased dramatically when Pb concentration was 100 mg · L^-1（P〈0.01 ）. Root activity of B. biternata pretreated with various concentrations of Pb was lower than that of the control, and decreased with the prolonged treatment time. With Pb concentration increasing, Pb content in each part of B. biternata first increased and then decreased. Pb contents in the leaves and stalks reached their maximum values at Pb concentration of 20 mg · L^-1. Underground roots exhibited the highest Pb content at Pb concentration of 10 mg · L^-1 , and its accumulation reached 2 080.89 mg· kg^-1 （ P〈0.01 ）. At the same concentration, the Pb content in roots was the highest, followed by stems and leaves in order. Translocation factor of Pb for B. biternata was less than 0.1. When Pb concentration ranged from 10 to 20 mg· L^-1 , the root tolerance index of B. biternata was more than 1.0, and the index decreased with the increase of Pb concentration.