【作者】 吴惠芳；

【导师】 刘鹏；

【作者基本信息】 浙江师范大学 ， 生态学， 2011， 硕士

【摘要】 本试验以两种具有相对较强耐锰性及富集作用的植物品种龙葵和小飞蓬为材料,分别采用水培和土培法培养植物,探究锰胁迫下这两种植物的生长特性及锰在植物体内的运输赋存形态,探讨了锰胁迫下龙葵、小飞蓬根系分泌物对土壤根际微生态的影响,包括土壤微生物数量、土壤酶活性及土壤锰形态的影响。本研究结果总结如下：1.Mn胁迫下,随着Mn浓度的升高,龙葵和小飞蓬的叶面积、根长、存活率都有不同程度的下降,株高先略高于对照,而后逐渐下降。龙葵、小飞蓬叶中还原性抗坏血酸(ASA)含量随着锰浓度的升高显著增加,之后随着锰浓度的继续增加,ASA含量下降,但总体上还是大于对照。两者的脱氢抗坏血酸(DHA)含量随着锰浓度的增加显著增加,都在锰浓度为16 mmol/L时达到最大值。在各相应锰浓度下龙葵的ASA含量大于小飞蓬,且DHA含量增加幅度比小飞蓬小。两种植物总抗坏血酸含量呈上升趋势,还原型抗坏血酸含量在总抗坏血酸含量中的比例逐渐降低。2.叶绿素含量均随着培养液中Mn含量的增加显著降低。两种植物的最大光化学量子产量(Fv/Fm)、最大荧光(Fm)、同期光合量子产量(Yield)和表观光合电子传递速率(ETR)均随着Mn离子浓度的增加明显降低；两种植物的初始荧光(Fo)均呈下降上升趋势,而非光化学荧光淬灭系数(NPQ)有上升趋势,但处理之间NPQ变化差异不明显。试验表明在锰胁迫下两种植物的光合作用电子传递过程和电子传递速率被抑制。3.随着锰浓度的增加,龙葵和小飞蓬各组织内锰含量不断增加,达极显著水平。分别在8 mmol/L时达到最大值,其中组织吸收量大小顺序是：叶>茎>根。在各相对应的锰浓度下,龙葵各组织中单位锰含量大于小飞蓬。两种植物对锰的吸收能力虽没有达到超富集植物的要求,但均表现出较强的富集锰元素和耐锰的能力。4.锰胁迫下,诱导产生植物络合素(PCs)有上升后下降的趋势,但含量较少且与对照相比无明显变化,可能和诱导时间有关或者表明锰胁迫下植物组织并不能有效地产生PCs以螯合锰而缓解其毒害；而PCs产生的前体物质谷胱甘肽(GSH),及类金属硫蛋白(MTL)的诱导量和锰浓度之间存在一定相关性,两个品种的GSH、MTL含量随锰浓度变化分别呈现先下降后上升和先上升后下降的规律。实验表明GSH和MTL对不同锰处理浓度的响应都很敏感。所以二者的诱导量变化可作为植物耐锰胁迫的参考指标。随Mn处理浓度增大,龙葵受Mn胁迫的影响比小飞蓬小。5.随锰浓度的升高,龙葵和小飞蓬的植物多酚含量有上升趋势,但没有显著的剂量效应,之后呈下降趋势。两种植物中的单宁含量变化较大,叶片可溶缩合单宁(ECT)、叶片蛋白质缩合单宁(PCT)、纤维素缩合单宁(FCT)的含量均随着锰处理浓度的增大而增加。随着锰处理浓度的增高,ECT的浓度呈现下降的趋势。锰胁迫对ECT、PCT和FCT各组分在TCT中的比例分布没有显著影响。6.随锰浓度的增加,两种植物真菌数量逐渐减少,细菌、放线菌数量也均呈波动性变化。低浓度锰可刺激脲酶、磷酸酶的活性；高浓度锰不同程度地抑制脲酶、蛋白酶、转化酶、过氧化氢酶、磷酸酶活性；多酚氧化酶活性在高浓度下反而有增加。小飞蓬根际土壤中脲酶、多酚氧化酶、蛋白酶、磷酸酶、转化酶之间存在显著或极显著的正相关性,六种土壤酶的相关程度为转化酶>蛋白酶>多酚氧化酶>脲酶>磷酸酶>过氧化氢酶。龙葵根际六种土壤酶的相关程度为脲酶>转化酶>磷酸酶>蛋白酶>过氧化氢酶>多酚氧化酶,表明转化酶对锰污染最为敏感。7.随着锰处理浓度的增加,根际土壤各形态锰含量都有所增加。植物根际锰形态分布特征与6种土壤酶活性之间的线性回归相关性分析表明,两种植物中6种土壤酶均与某一种形态的锰或几种形态的锰的含量呈显著直线相关。两种植物各形态锰含量与土壤酶活性的相关关系优于总量锰,因此可将锰各形态含量关系作为评价红壤锰污染程度的主要生物学指标。更多还原

【Abstract】 Manganese (Mn) is a necessary element for plant growth, but excess Mn cause serious chlorosis and inhibite the plants growth, and dramatically increase accumulation of Mn in both shoots and roots, furthermore, inhibite the absorption of Ca, Mg and Zn. Mn toxicity is a serious agricultural problem in acid-soil area. In addition to aluminum (Al), manganese toxicity in acid soil become one of the most important factors which can limit plant growth. We used two kinds of relatively strong accumulation of manganese and manganese-resistant varieties of plants--Conyza canadensis and Solanum nigrum as materials in this test. The pot and hydroponic culture experiment was conducted under different Mn stress to explore plant growth characteristics and transport of manganese, to study the effects of root exudates on soil and rhizosphere micro effects, including soil microorganisms, soil enzyme activity and morphology of soil manganese, to reveal the resistance to manganese toxicity and manganese enrichment process of reconciliation of the two enrichment plants. Further more, it could provide a theoretical basis for the applications of manganese and promote further research of phytoremediation of contaminated soil.The results were summarized as follows:1. Leaf area, root length and survival rate of the two plants significantly decreased in various degree with the increase of Mn concentration, and plant height first increased compared with control(0.005 mmol/L) and then decreased gradually. Ascorbic Acid(ASA) concentrations in leaves of Solanum nigrum and Conyza canadensis significantly increased in low manganese concentration, then ASA contents had a reduced trend with the increasing manganese concentration, but were still greater than control. Dehydro ascorbate(DHA) content significant increased in manganese concentration of 16mmol/L The ASA content of Solanum nigrum was more than that of Conyza canadensis in various corresponding concentration of manganese, and the rate of increase levels of DHA was smaller than Conyza canadensis. Total ascorbic acid content of two plants was rising, the proportion of reduced ascorbic acid content of the total content ascorbic acid was decreased with the increasing manganese concentration.2. The Chlorophyll contents remarkably decreased with increasing Mn content. The responses of chlorophyll fluorescence parameters in leaves of these two species indicated that maximum quantum yield(Fv/Fm), maximum fluorescence(Fm), effective quantum yield of photosystem II(Yield), electron transfer rate(ETR) also obviously decreased with an increase of Mn. On one hand, their minmal fluorescence(Fo) first decreased and then increased with the increment of Mn concentration at the medium level, and on the other hand, there was an upward trend in non-photochemical quenching(NPQ)of these two species,but it did not show significant difference among various Mn concentrations. The results above indicated that electronic transmition process was inhibited and electronic transmition rate was decreased in Photosynthesis of these two species. Growth and development of Solanum nigrum and Conyza canadensis were influenced to different degrees by Mn toxicity, and Solanum nigrum showed stronger tolerance to Mn toxicity than Conyza canadensis, so it was more suitable for phytoremediation of Mn polluted areas.3. Mn concentration in the leaves stems roots of Conyza canadensis and Solanum nigrum significantly increased with increased Mn concentration (P<0.01) and Mn was preferentially accumulated in the leaf. With the increase of the concentration of manganese, Mn content in the organization of Solanum nigrum and Conyza canadensis significantly increased and reached the maximum at 8 mmol/L. The order of Mn absorption in tissue was:leaves>stems>roots. Mn contents in the organizations of Solanum nigrum was more than those of Conyza canadensis in various corresponds Mn concentrations. The absorption capacity of Mn of these two plants did not meet the requirements of being hyperaccumulator, but they showed good metal-enrichment of Mn and have good tolerant ability of Mn.4. Little Phytochelatins(PCs) could be detected in roots and leaves of these two plants under Mn stress, which could be caused by shorter inducing time or PCs were not responsive to Mn stress. The content of Glutathione(GSH) and Metallothionein-like(MTL) were more sensitive to Mn stress, and they presented in similar change patterns. MTL and GSH increased rapidly first and then dropped rapidly with the increase in the concentration of manganese and it indicated that there were some correlation between the physiochemical values and Mn concentrations in plants’s tissues due to increasing the supply of Mn2+. The contents of Totle Non-protein SH(TNP-SH) and GSH were significantly (P<0.05)promoted in 8mmol/L Mn2+ when compared to the control respectively. The content of MTL in Solanum nigrum significantly increased under 8 mmol/LMn2+, while this of Conyza canadensis was promoted significantly under 2 mmol/L Mn2+ and 4 mmol/L Mn2+. The MTL and MTL were maintained at a higher level in Solanum nigrum in comparison with Conyza canadensis under the corresponding concentration. GSH and MTL could be effective response index to Mn stress. Solanum nigrum showed stronger tolerance to Mn toxicity than Conyza canadensis,so it was more suitable for phytoremediation of Mn polluted areas.5. Plant polyphenol content in leaves of these two plants increased under low manganese concentration, but it didn’t have significant dose effect, and then the polyphenol content gradually decreased with increasing manganese concentration. There was a little change of tannin contentin in leaves of these two plants. Extractable Condensed Tannin(ECT), Protein bound Condensed tannin(PCT) and Fibre bound Condensed tannin(FCT) content in leaves increased with increasing concentration of manganese. With the increase of Mn concentration, ECT concentration showed a downward trend. The the proportion of ECT, PCT and FCT in the TCT were not significantly affected under Mn stress.6. The fungi quantity decreased gradually and a fluctuation in the population of bacteria and actinomyces was noticed with increasing Mn conten. Lower Mn concentration could stimulate the activities of urease and phosphatase, the higher Mn concentration could inhibit the activities of urease, protease, invertase, catalase and phosphatase to varying degrees and raise polyphenol oxidase activity. The correlation analysis of Conyza canadensis showed that there was a very significant negative correlation between different Mn stress and the activities of soil enzyme and the correlation degree was invertase> protease>polyphenol oxidase>urease>phosphatase>catalase.There was a significant positive correlation (P<0.05)in the activities of urease, polyphenol oxidase, protease, phosphatase, invertase, so these enzymes were of the similar adaptability to Mn stress. On the other hand, the activities of soil enzyme and the correlation degree of Solanum nigrum was urease> invertase> phosphatase> protein> catalase> polyphenol oxidase. There was a significant or very significant positive correlation among urease, protease, phosphatase, invertase of Solanum nigrum, while there was a significant correlation between catalase and urease, invertase, phosphatase. Activities of urease and invertase was mostly sensitive to Mn stress among these six soil enzymes, indicating that the invertase can be used as a biological index of manganese pollution.7. With the increase of Mn concentration, various forms of Mn content significantly increased.There was a significant or very significant negative correlation between different Mn chemical forms and 6 kinds of soil enzyme activity.There was not a significant negative correlation between total Mn content and soil enzyme activity, but there was little negative correlation between urease activity and total Mn content. Over all, there was a significant negative or positive correlation between urease, acid phosphatase, catalase activity and weakly adsorbed Mn, specific adsorption Mn. Because the correlation between the contents of different Mn forms and soil enzyme activities was higher than the correlation between total Mn content and soil enzyme activities, the relationship between the contents of different Mn forms can be used as the main biological index for evaluating Mn pollution degree of red roam.更多还原