重金属离子对2种草坪草荧光特性及根系形态的影响

Impacts of heavy metals on the fluorescence characteristics and root morphology of 2 turfgrass species

以高羊茅和多年生黑麦草为试验材料,分别设置Cd2+、Cu2+、Zn2+、Pb2+不同浓度处理,研究4种重金属离子对其荧光特性及根系形态的影响。结果表明,高羊茅在4种重金属离子处理下,其最大量子产量(Fv/Fm)值均低于对照,说明高羊茅在受到重金属离子胁迫后,其PSⅡ活性受到伤害;多年生黑麦草在Cd2+不同浓度处理下,其Fv/Fm值均略高于对照,但差异不显著,说明Cd2+胁迫对多年生黑麦草的PSⅡ系统的活性影响不大;但是Cu2+和Zn2+浓度分别达到500mg/kg及以上时,对多年生黑麦草Fv/Fm值影响较大,均显著低于对照;同时,多年生黑麦草还表现出低浓度Zn2+促进PSⅡ系统活性的作用,但随着浓度升高,表现出对PSⅡ系统越来越强的抑制作用;在4种重金属离子不同浓度处理下,2种草坪草的光化学淬灭系数(qP)和电子传递速率(ETR)值均低于对照,说明其光合活性和电子传递效率均受到影响;经过4种重金属离子处理后,除部分离子低浓度处理外,高羊茅总根长、根表面积、总分叉数和总根尖数均显著低于对照,并且有随着离子处理浓度升高而逐渐降低的趋势;多年生黑麦草根系则表现出对低浓度重金属离子抗性较强,对高浓度重离子抗性较差,并且也有随浓度升高而不断降低的趋势。

The impacts of Cu^2＋ , Zn^2＋ , Pb^2＋ and Cd^2＋ stresses on fluorescence characteristics and root morphology of tall fescue （Festuca elata） and perennial ryegrass （Poa pratensis） were studied. The Fv/Fm of tall rescue under Cu^2 ＋ , Zn^2＋ , Pb^2＋ and Cd^2＋ stresses were lower than that in the controls suggesting that the activity of PSI was weakened. However, it was quite different for perennial ryegrass. The Fv/Fm, under Cd^2＋ stress was slightly higher than that in the controls indicating that the impact of Cd^2＋ was not significant. However, it was significantly reduced when the concentrations of Cu^2＋ and Zn^2＋ reached 500 mg/kg or more. Meanwhile, the lower concentrations of Zn2. resulted in an improving effect on the PS Ⅱ system. The qP and ETR of both species under the stresses of 4 heavy metals were lower than those in the controls suggesting that the photosynthetic activity and electron transformation efficiency were inhibited. Except at low concentrations, the root length, root area, numbers of root forks and tips of tall rescue were significantly lower than those in the controis when under stress from four heavy metals： there was a decreasing trend with increasing stress concentration. Perennial ryegrass showed a strong resistance to the stresses when heavy metals were at low concentrations and vice versa.