铅、锌、镉单一及复合胁迫对多年生黑麦草生长及生理特性的影响

【目的】探究铅（Pb）、锌（Zn）、镉（Cd）单一及复合污染对多年生黑麦草生长和生理特性的影响，为检验多年生黑麦草对土壤重金属污染的抗性能力提供科学依据。【方法】采用沙培法，研究CK（不加任何重金属盐）、Pb、Zn、Cd单一及复合胁迫对多年生黑麦草株高、叶宽、根长、生物量及光合色素含量、脯氨酸（Pro）、过氧化物酶（POD）、超氧化物歧化酶（SOD）、可溶性糖（SS）和丙二醛（MDA）等生理指标的影响，利用隶属函数对生长和生理指标进行综合评价。【结果】Pb-Zn-Cd处理对多年生黑麦草株高、叶宽、根长、分蘖数、地上生物量、地下生物量、根冠比、POD活性和SOD活性影响最大，其中株高、叶宽、根长、分蘖数、地上生物量、地下生物量和根冠比较CK分别下降61.9%、35.9%、66.5%、72.1%、92.8%、94.2%和20.1%，POD和SOD活性较CK分别增加64.6%和3.8倍。Zn处理对多年生黑麦草的叶绿素a含量、类胡萝卜素含量、叶绿素总量和光合色素总量的影响最大，较CK分别显著下降28.6%、31.9%、20.6%和22.9%（P<0.05，下同），而对叶绿素b含量抑制最大的是Cd处理，其次是Pb-Zn-Cd处理，较CK分别下降20.3%和20.0%；所有重金属处理均使多年生黑麦草Pro含量显著增加；SS和MDA含量受Zn-Cd处理抑制最明显，较CK分别显著增加56.4%和7.0倍；复合胁迫对多年生黑麦草各指标的影响存在交互作用。通过隶属函数综合评价可知多年生黑麦草对各处理的耐受性为:Zn > CK > Cd > Zn-Cd > Pb-Zn > Pb > Pb-Cd > Pb-Zn-Cd。【结论】多年生黑麦草对Zn胁迫存在一定的耐受性，而对Pb-Zn-Cd复合胁迫的耐受性最差。

Effects of single and combined stresses of lead,zinc and cadmium on growth and physiological characteristics of perennial ryegrass

【Objective】To explore the effects of single and combined pollution of lead(Pb), zinc(Zn), cadmium(Cd) on the growth and physiological characteristics of perennial ryegrass, and to improve the scientific basis for testing the resistance ability of perennial ryegrass to soil heavy metal pollution.【Method】Used sand culture method, the effects of single and combined stress of CK(no heavy metal), Pb, Zn and Cd on plant height, leaf width, root length, biomass, chlorophyll content, proline(Pro), peroxidase(POD), superoxide dismutase(SOD), soluble sugar(SS) and malondialdehyde(MDA) of perennial ryegrass were studied by pot experiment, and growth and physiological characteristics indexes were comprehensively evaluated by subordinate function method.【Result】Pb-Zn-Cd treatment had the greatest effect on plant height, leaf width, root length, tiller number, aboveground biomass, underground biomass, root-shoot ratio, POD activity and SOD activity of perennial ryegrass, plant height, leaf width, root length, tiller number, above ground biomass, underground biomass, root-shoot ratio decreased by 61.9%, 35.9%, 66.5%, 72.1%, 92.8%, 94.2% and 20.1% compared to CK, respectively. POD activity and SOD activity increased by 64.6% and 3.8 times compared with CK. Compared with CK treatment, Zn treatment had the greatest effect on chlorophyll a content, carotenoids content, total chlorophyll content and total photosynthetic pigment content, and they significantly decreased by 28.6%, 31.9%, 20.6% and 22.9% compared with CK(P<0.05, the same below). Cd treatment had the largest inhibition effect on chlorophyll b content, followed by Pb-Zn-Cd treatment, and they were decreased by 20.3% and 20.0% compared with CK. All heavy metal treatments resulted in significant increase in Pro content in perennial ryegrass. The contents of SS and MDA were most affected by Zn-Cd treatment, increased by 56.4% and 7.0 times compared with CK. The effects of combined stress on the indexes of perennial ryegrass were interactive. According to the comprehensive evaluation of membership function, the tolerance of perennial ryegrass was Zn> CK> Cd> Zn-Cd> Pb-Zn> Pb> Pb-Cd> Pb-Zn-Cd.【Conclusion】Perennial ryegrass has some tolerance to Zn stress, but it has the worst tolerance to Pb-Zn-Cd compound stress.