栾树和榉树对Pb、Zn的耐性和富集特征研究

发布时间：2018-05-01 12:16

  本文选题：木本植物 + 重金属　； 参考：《中南林业科技大学》2017年硕士论文

【摘要】：土壤重金属污染是一个日益严峻的环境问题,植物修复是一种环境友好的土壤重金属治理的方法,广义上植物修复还具有重建植被、修复景观、改良土壤性质等功能。在此意义上,木本植物以生物量大、生长周期长成为首选对象。重金属对植物的毒害作用表现在各个方面,其中植物光合作用受到抑制是重金属毒害的显著症状。为此,本文以阔叶树种栾树和榉树1年生幼树为对象,采用室内盆栽试验,通过连续4次分别将PbCl2、ZnCl2掺入盆栽土壤,研究连续Pb、Zn单一胁迫处理对栾树和榉树叶片的气体交换参数、叶绿素荧光参数和富集等方面的影响,对比分析2种植物对Pb、Zn耐性能力,试图找出2种植物光合生理参数与Pb、Zn浓度之间的定量响应关系。研究结果将为耐性木本植物的筛选提供数据支撑。主要研究结论如下:1、连续Pb、Zn处理下,栾树和榉树的最大净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和气孔阀值(Ls)均表现为处理组对照,且差异性显著(P＜0.05),胞间C02(Ci)则表现为处理组对照,出现了由非气孔限制引起的Pn下降。并且,随着Pb、Zn处理次数的增多,在处理组中,栾树和榉树的Pn、Tr、Gs、Ls呈下降趋势,Ci呈上升趋势。在Pb、Zn单一胁迫下,随着Pb、Zn处理浓度的升高,榉树表现出的光合能力高于栾树。重金属Zn对二者光合作用的抑制比Pb强。2、Pb、Zn处理下栾树和榉树PSII最大光化学效率(Fv/Fm)、实际光化学效率(ETR)低于对照,且ETR和对照相比差异显著(P＜0.05);二者的光化学猝灭(qP)均显著降低,非光化学猝灭(NPQ)显著升高,说明栾树和榉树在Pb、Zn胁迫下发生了明显光抑制现象,但可以通过热的形式将PSII的过剩光能耗散掉。随着Pb、Zn处理次数的增多,在处理组中,栾树和榉树的Fv/Fm、ETR、qP总体呈下降趋势,NPQ呈上升趋势。对比二者在Pb、Zn胁迫下的光保护能力,我们得出,在低浓度Pb处理下,栾树的qP和NPQ高于榉树,造成栾树的光合能力高于榉树,但随着处理次数的增多,栾树qP和NPQ低于榉树,使得榉树表现出更强的光合能力。在Zn处理下,栾树和榉树的Fv/Fm、ETR、qP、NPQ较对照而言,其变化幅度高于Pb处理,说明了 Zn对于这两种植物的伤害大于Pb;榉树在第1次Zn处理后,很快显示出了比栾树更好的光保护能力,在第2和第3次处理后,同对照相比,栾树qP的下降幅度高于榉树,这说明了榉树比栾树更耐Zn胁迫。3、在连续Pb、Zn处理下,栾树和榉树各部位Pb2+、Zn2+含量明显地高于对照相应部位。根是栾树和榉树吸收积累Pb2+的主要部位,Pb处理组的根吸收量比对照组高出6.42-32.89倍,茎的Pb含量小于根,Pb处理组比对照组高出2.95-11.67倍,Pb在叶的积累量比茎稍高,但从增加倍数来看,Pb处理组比对照组仅高出2.63-8.85倍,在整株中表现出来的富集能力均为:栾树榉树;而在吸收积累Zn2+的方面,根和茎的积累量相当,而叶对Zn2+的吸收量较少。在吸收富集Zn的能力方面栾树要优于榉树,但在Zn处理下,榉树对Zn的吸收富集更具持续性。不同的重金属在植物体内的分配率存在差异,栾树和榉树从土壤中吸收的Pb2+主要积累在根部,占了总吸收量的57.09%-76.68%;迁移至茎部的数量占总量的6.95%-15.98%;迁移至叶部的数量占了总量的10.36%-30.32%;Zn2+在榉树根茎叶部的分配率为表现为:42.99%、29.85%、27.16%,栾树为:37.17%、33.81%、29.02%,说明了 Zn2+在栾树和榉树中的分配率高于Pb2+。在富集系数方面,栾树和榉树对Pb、Zn的富集系数均随着处理次数的增多而减少,其中,栾树富集Pb、Zn的能力要高于榉树。4、基于Lake模型分析单一 Pb、Zn胁迫下栾树和榉树的耐性能力得出,随着Pb处理次数的增多,榉树耐Pb的能力逐渐表现为高于栾树;两种植物对Zn的耐性不强,相比之下,榉树对Zn的耐性高于栾树。5、由光合、荧光参数对Pb、Zn污染剂量的响应,可以得出栾树对土壤Pb污染的耐受范围在1.80-2.15g/kg之间,榉树为1.85-2.25g/kg;而连续Zn处理对栾树和榉树所造成的破坏使得二者在土壤中Zn含量(≤0.5g/Kg)时,光系统中的各参数下降明显,最终表现为对Zn的耐性均不高,但从试验周期来说,榉树比栾树更能存活在Zn污染更严重的土壤中。
[Abstract]:Heavy metal pollution in soil is an increasingly serious environmental problem. Phytoremediation is an environmentally friendly method of remediation of heavy metals in soil. In the broad sense, plant restoration also has the functions of reconstructing vegetation, restoring landscape and improving soil properties. In this sense, the woody plants are the first choice for the large amount of raw materials and long growth cycle. The toxic effects of plants are manifested in various aspects, among which plant photosynthesis is inhibited as a significant symptom of heavy metal poisoning. For this reason, the 1 year old trees of broad leaved tree and beech tree were used as the target, and PbCl2 and ZnCl2 were added into the potted soil by indoor pot experiments, and the single stress treatment of Pb and Zn was studied. The effects of the gas exchange parameters, chlorophyll fluorescence parameters and enrichment on the leaves of the trees and beech trees were analyzed. The tolerance ability of 2 plants to Pb and Zn was compared and analyzed. The quantitative response relationship between the photosynthetic physiological parameters of 2 plants and the concentration of Pb and Zn was tried to find out. The results will provide data support for the screening of resistant wood plants. 1, 1, under continuous Pb, Zn treatment, the maximum net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) and stomatal threshold (Ls) of the tree and beech were all compared with the treatment group, and the difference was significant (P < 0.05), and the intercellular C02 (Ci) was shown as the control of the treatment group, and the Pn decreased by the non stomatal restriction. And, with Pb, the Zn treatment times In the treatment group, the Pn, Tr, Gs and Ls of the tree and the beech showed a downward trend, and the Ci showed an upward trend. Under the Pb, Zn stress, with the increase of Pb and the concentration of Zn, the photosynthetic capacity of the beech tree was higher than that of the tree. The inhibition of the photosynthesis of the heavy metal Zn to the two was stronger than the Pb.2. Fm), the actual photochemical efficiency (ETR) was lower than that of the control, and the difference between ETR and photographic ratio was significant (P < 0.05); the photochemical quenching (qP) of the two groups decreased significantly, and the non photochemical quenching (NPQ) increased significantly. It indicated that the light inhibition of the tree and beech trees under the stress of Pb and Zn was obvious, but the excess light energy consumption of PSII could be dissipated through the form of heat. With the increase of the number of Pb and Zn processing, in the treatment group, the Fv/Fm, ETR and qP of the trees and the beech trees showed a downward trend, and the NPQ showed an upward trend. Compared with the light protection ability under the stress of Pb and Zn, we concluded that the qP and NPQ of the trees were higher than the beech trees under the low concentration of Pb treatment. The photosynthetic capacity of the tree was higher than that of the beech tree, but with the increase of the treatment times. More, the qP and NPQ were lower than the beech trees, making the beech stronger photosynthetic capacity. Under the Zn treatment, the Fv/Fm, ETR, qP, NPQ of the trees and beech trees were higher than the control of Pb treatment, which indicated that the harm of Zn to these two plants was greater than Pb, and the beech tree showed better light protection than the tree after first Zn treatment. After second and third treatments, the decrease of qP was higher than that of the beech tree, which showed that the beech tree was more resistant to Zn stress than that of the beech tree, and that the content of Zn2+ content was obviously higher than that of the photographing site. The content of Zn2+ was significantly higher than that of the photographic site. The root was the main part of the accumulation of Pb2+ in the root of the tree and the beech tree, and the root absorption of the Pb treatment group. The amount of Pb in the stem was less than that of the control group, the content of the stem was less than that of the root, the Pb treatment group was higher than the control group 2.95-11.67 times, and the accumulation of Pb in the leaves was slightly higher than that of the stem, but from the increase, the Pb treatment group was only 2.63-8.85 times higher than the control group, and the accumulation energy in the whole plant was all: the 6.42-32.89 beech tree; and the root of the accumulation of Zn2+. The accumulation of stems is equal, but the absorption of Zn2+ is less. In the capacity of absorbing and enriching Zn, the tree is better than the beech tree, but the absorption and enrichment of the beech tree to Zn is more persistent under the Zn treatment. The distribution rate of different heavy metals in the plant is different, and the Pb2+ of the tree and beech from the soil is mainly accumulated in the root. The total absorption of 57.09%-76.68%; the number of migrating to the stem accounted for 6.95%-15.98% of the total amount; the number of migrating to the leaves accounted for 10.36%-30.32% of the total amount; the distribution rate of Zn2+ in the root and leaf of the beech was 42.99%, 29.85%, 27.16%, and 37.17%, 33.81%, 29.02%, indicating that the allocation rate of Zn2+ in the tree and beech was higher than that of Pb2+. in the rich. In the aspect of set coefficient, the enrichment coefficient of Pb and Zn in Luan and beech decreased with the increase of the number of processing times. Among them, the ability to enrich Pb and Zn was higher than that of beech.4. Based on Lake model, the tolerance ability of Luan tree and beech under Zn stress was analyzed. With the increase of Pb treatment times, the ability of Pb to resist Pb was gradually higher than that of Luan. The tolerance of the two plants to the Zn was not strong. In contrast, the tolerance of the beech tree to the Zn was higher than that of the.5. In response to the photosynthesis, the fluorescence parameters to the Pb, Zn pollution dose, it could be found that the tolerance range of the Pb pollution in the soil was between 1.80-2.15g/kg and the beech was 1.85-2.25g/kg; and the damage caused by the continuous Zn treatment to the tree and beech tree caused two people. When the Zn content in the soil (less than 0.5g/Kg), the parameters of the optical system decreased obviously, and the endurance of Zn was not high, but from the test period, the beech tree was more able to survive in the more serious soil contaminated by the Zn.

【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;X173;S792.99
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本文编号：1829318