【作者】 周晓星；

【导师】 孙振元；

【作者基本信息】 中国林业科学研究院 ， 园林植物与观赏园艺， 2012， 博士

【摘要】 重金属作为最常见的不可降解的污染物，对生物的危害日益受到全世界的关注。镉污染范围广、毒性较强，这主要是因为镉具有易被植物吸收与积累的特点，可造成植物的生理过程受到抑制，甚至死亡。柳树（Salix spp.）是Cd²⁺高积累型速生树种，对修复镉引起的环境污染有极大潜力。因此研究柳树对镉胁迫下的生长与生理响应有意义。主要结果如下：1.采用沙培法，研究Cd²⁺胁迫对旱柳、银芽柳、杞柳根系形态的影响。在Cd²⁺处理6天、9天时，旱柳根系长度显著低于对照；在处理9天时，杞柳根系长度显著低于对照；在处理9天时，银芽柳根系长度也低于对照，但差异不显著，说明在Cd²⁺处理下，银芽柳对镉的耐性较旱柳、杞柳强。在Cd²⁺处理6天、9天时：旱柳根系的表面积、体积在较对照无明显差异，但是根系中起主要吸收功能的直径≤0.5mm的根系长度、表面积、体积明显低于对照。可能因为直径≤0.5mm的根系吸收能力强，被动吸收Cd²⁺多，富集的镉浓度大，进而受到镉的伤害严重。杞柳根系长度、表面积、平均直径、根尖数量以及直径≤0.5mm的根系长度、表面积、体积，在Cd²⁺处理3天、6天时，与对照无显著差别；在处理9天时，则显著低于对照，印证了Cd²⁺处理强烈抑制根尖的产生的现象。2.以沙培条件下浇灌Cd²⁺处理液的方法研究镉在旱柳、杞柳、银芽柳中的积累特性及Cd²⁺处理对钙、镁、钾三种元素分配的影响。结果表明，随着Cd²⁺处理时间的延长，三种柳树根、茎、叶中的镉浓度逐渐升高，在处理9天时，三种柳树地上部的镉浓度均超过了100mg/kg。镉处理9天时，三种柳树的地上部、地下部生物量均未受到显著影响，三种柳树对镉表现出较强的抗性，具备了镉修复植物的潜在特性。Cd²⁺处理下，三种柳树根中的镉浓度远大于茎和叶片，镉在植物体内被限制运输到茎、叶，这在一定程度上降低了镉对植物地上部的毒害。Cd²⁺处理下，三种柳树根中的钾浓度显著降低，且处理9天时茎、叶中的钾浓度较3天降低，三种柳树根系对钾的吸收能力和钾向地上部的转运能力均受镉的抑制。Cd²⁺处理9天，旱柳根、茎、叶中的镉浓度较3天分别提高了3.04、2.36和21.56倍，旱柳地上部对镉的富集能力随着处理时间的延长持续增加。Cd²⁺处理3、6天时，镉的分布比例以地上部为主，处理时间延长至9天时，镉向地上部的转运能力受到了抑制，根中镉的分布比例超过了地上部。Cd²⁺胁迫下，旱柳根系加速了对钙的吸收，并将其转运到地上部，处理9天时旱柳茎中的钙浓度较3、6天分别显著上升了21.73%、23.66%。旱柳茎、叶对镁的转运能力受Cd²⁺的抑制。Cd²⁺胁迫下，旱柳根系对钾的吸收能力和钾向地上部的转运能力均受镉的抑制，处理9天时旱柳根中的钾浓度较3、6天分别显著下降了51.98%和66.79%。Cd²⁺胁迫下，旱柳根中镁的分布比例显著升高，处理9天时较3、6天显著提高了80.22%和77.57%。Cd²⁺处理下，三种柳树中，除旱柳根中镉的分布比例与镁的分布比例显著正相关、杞柳茎中钾的分布比例与镉的分布比例显著正相关外，矿质元素的其他分配格局均未受到镉的显著影响。旱柳、杞柳、银芽柳对矿质元素的分配具有较强的调节能力。3.以盆栽银芽柳为材料，利用Mini-Imaging-PAM荧光成像测定系统，研究了Cd²⁺胁迫下叶片叶绿素荧光参数的变化及其光响应曲线。结果表明，初始荧光Fo与最大荧光Fm随着Cd²⁺浓度的增大而呈现先升后降的趋势，Fo与Fm在200mg/L的Cd²⁺处理4周时达到最高值，400mg/L的Cd²⁺处理则显著下降；PSⅡ最大光化学效率（Fv/Fm）与PSⅡ潜在光化学效率（Fv/Fo）显著受Cd²⁺胁迫抑制，但随Cd²⁺浓度的增加呈先降后升的变化趋势。Cd²⁺胁迫下各叶绿素荧光参数的光响应结果表明，PSⅡ实际光量子效率Y（Ⅱ）、荧光淬灭系数（qP）随光化光强度的增加呈下降趋势，而同光强下高浓度Cd²⁺使Y（Ⅱ）与（qP）显著降低；PSⅡ调节性能量耗散的量子产额Y（NPQ）、非光化学淬灭系数（qN）与表观电子传递速率（ETR）则随着光强增加呈上升趋势，同光强下高浓度Cd²⁺处理显著提高Y（NPQ）、qN与ETR。Cd²⁺胁迫下，PSⅡ非调节性能量耗散的量子产额Y（NO）稳定在较低水平，同光强下Y（NO）随Cd²⁺浓度增加略有提高。说明，银芽柳通过调节PSⅡ反应中心开放程度与活性，对Cd²⁺胁迫表现出较强的耐性，高浓度Cd²⁺胁迫导致PSⅡ反应中心关闭或不可逆失活，表现出光抑制。基于以上研究结果，旱柳、杞柳、银芽柳对高浓度Cd²⁺胁迫均有较强抗性，可用于重度镉污染地区的植物修复，并且是选育用于重金属植物修复的柳树品种的良好材料。4.利用分类统计分析和Fisher判别分析，对银芽柳、垂柳、旱柳、蒿柳、杞柳、沙柳、苏172、苏799、垂爆柳9种柳属植物的叶长、叶宽、叶最宽处距叶尖距离、叶柄长、腋芽长、叶片密度和叶序比等7个指标进行分析，得出这9种柳属植物的判别函数，构建判别模型，再将这9种柳属植物的形态指标数据代入相应判别模型，检验其判别效果。结果表明，判别模型对柳属植物的识别正确率高于95%。更多还原

【Abstract】 As the most common non-degradable pollutants, heavy metal is harmful to organisms,which have caused an increasing concern around the world. Cadmium is a common, highlytoxic heavy metal. There is a cause that cadimium is easily absorbed and accumulated by plants,and thus it is easy to suppress the physiological processes in plants. It leads to inhibit theplants’ normal growth and development, even to death. Willow（Salix spp.） is a kind ofcadmium high-accumulation-type fast-growing tree, which has great potential forenvironmental cadmium pollution repair. There is academic significance to study physiologicalchanges in Salix under cadimium stress. Main results obtained are as following:1. Studied on the effect of Cd²⁺solution on morphology in root of Salix matsudana, Salixintegra, Salix leucopithecia under sand culture condition. The results showed that, under Cd²⁺stress for6days,9days, Salix matsudana root length was significantly lower than CK; treated9days, Salix integra root length was significantly lower than CK; treated9days, Salixleucopithecia root length was lower than CK without significantly difference. This showed thatSalix leucopithecia had stronger cadmium tolerance than Salix matsudana and Salix integraunder Cd²⁺stress.Under Cd²⁺stress for6days,9days, Salix matsudana root surface area, volume had nosignificant difference on CK; but roots （diameter≤0.5mm） which take leading role inabsorption, their length, surface area, volum were significantly lower than CK. It was probablycaused by their strong absorption, which passive absorpted and enriched more cadmium. UnderCd²⁺stress for3days,6days, in Salix integra, there was no significant difference betweentreatment and CK in root length, surface area, average diameter, root tip number androots（diameter≤0.5mm） length, surface area, volum; treated9days, there were significantdiffernces. This confirmed that the Cd²⁺stress strongly inhibited the growth of apical cell,resulted that root tip number was significantly lower than CK. 2. Studied on the cadmium accumulation characteristics and effect on the distribution ofmineral elements in Salix matsudana, Salix integra, Salix leucopithecia under highconcentration of Cd²⁺solution treatment with sand culture. The results showed that, with theprolonged Cd²⁺stress, concentration of cadmium in the three kind of willow roots, stems,leaves gradually increased. Treated9days under Cd²⁺stress, the cadmium concentrations inshoots of the three kind of willow were more than100mg/kg respectively; the shoots and rootsbiomass of the three kind of willow were not significantly affected; the three kind of willowhad strong resistance to cadmium, with the potential for cadmium phytoremediation plant.Under Cd²⁺stress, the concentration of cadmium in roots of the three kind of willow weremuch higher than stems and leaves. cadmium in plants was limitedly transported to the stems,leaves to reduce the poisoning of cadmium in shoots. Under Cd²⁺stress, the potassiumconcentration was significantly decreased in roots of the three kind of willow, and treated9days under Cd²⁺stress, potassium concentration in stems and leaves were lower than3days.Capacities of absorb potassium and transport potassium to aboveground in root of the threekind of willow were suppressed by Cd²⁺stress.Treated9days under Cd²⁺stress, the concentration of cadmium in root, stem, leaf of Salixmatsudana, increased3.04,2.36,21.56times respectively than treated3days; ability ofcadmium accumulation in shoot of Salix matsudana continued to increase with prolongedtreatment. Treated3,6days under Cd²⁺stress, the cadmium content in shoot of Salixmatsudana was more than root; treated9days, capacity of transport cadmium was suppressed,it resulted that cadium content in root was more than shoot. Under Cd²⁺stress, Salix matsudanaroot accelerated the absorption of calcium, and transported to shoot. Treated9days, theconcentration of calcium in stem of Salix matsudana significantly increased21.73%,23.66%than3days,6days respectively. The capacity of transport magnesium of Salix matsudana stem,leaf was suppressed by Cd²⁺stress. Treated9days, the concentration of potassium in Salixmatsudana root significantly decreased than3,6days by51.98%,66.79%respectively. UnderCd²⁺stress, the distribution ratio of magnesium in Salix matsudana root significantly increased, compared with treated3,6days, treated9days significantly increased80.22%,77.57%respectively.Under Cd²⁺stress, in the three kind of willow, the proportions of distribution of themineral elements were not significantly affect by Cd²⁺stress except that the proportions ofdistribution of magnesium and cadmium in root of Salix matsudana were significantlypositively correlated, and the proportions of distribution of potassium and cadmium in stem ofSalix integra were significantly positively correlated. Salix matsudana, Salix integra, Salixleucopithecia had strong abilities to regulate the distribution of mineral elements.3. The efects of Cd²⁺stress on rapid light-response curves of photochemical andnon-photochemical chlorophyll fluorescence quenching parameters including darkfluorescence yield （Fo）, maximal fluorescence yield （Fm）, maximal PSⅡ quantum yield（Fv/Fm）, and latent PSⅡ quantum yield （Fv/Fo） of Salix leucopithecia were investigatedunder different concentrations of Cd²⁺solutions （0,50,100,200,400mg/L） byMini-Imaging-PAM Chlorophyll Fluorometer.The results showed that Fo and Fm present trend of first increased and then decreased, andthe two parameters reached the maximum when Salix leucopithecia were subjected to200mg/L Cd²⁺solution after four weeks. The Fv/Fm declined significantly under cadmium-bearingsolution, but it was higher in the same Cd²⁺solution after four weeks than after two weeks. TheFv/Fm rebounded slightly in200mg/L Cd²⁺condition after two weeks and then dropped tothe minimum in the same condition after four weeks. Fv/Fo was also inhibited significantly byCd²⁺stress, and showed the similar trend with the changes of Fv/Fm.The rapid light-response curves of chlorophyll fluorescence parameters were alsomeasured at various light intensities （0,20,60,100,300,500,600,800,1000, and1200μmol·m-2·s-1）. The effective PSⅡ quantum yield（Y（Ⅱ）） and coefficient of photochemicalquenching（qP） decreased with the increase of light intensity. The Y（Ⅱ） and qP declinedsignificantly subjected to high concentration of Cd²⁺solution compared with low concentrationunder the same light intensity. The parameters of quantum yield of regulated energy dissipation（Y（NPQ））, coefficient of nonphotochemical quenching （qN）, and electron transportrate （ETR） increased with elevation of light intensity. The Y（NPQ）, qN, and ETR increasedsharply subjected to high concentration of Cd²⁺solution compared with low concentrationunder the same light condition. Quantum yield of non-regulated energy dissipation（Y（NO））kept a lower level, although Y（NO） increased slightly with the aggrandizement of light intensity.The results indicate that Salix leucopithecia has strong tolerance to Cd²⁺stress by irreversibleinactivation of PSⅡreaction centers. However, under high concentration of Cd²⁺solution forprolonged stress, PSⅡreaction centers were closed or irreversible inactivated with showing thephenomenon of photoinhibition.Therefore, Salix matsudana, Salix integra, Salix leucopithecia have strong tolerance tohigh concentration Cd²⁺stress. They can be used for phytoremediation of severe cadmiumpolluted area, and they are good material for breeding of willow varieties for heavy metalphytoremediation.4. Using classification statistical function and Fisher discriminate function, analyzed7indexes （leaf length, leaf width, distance from the widest to the tip, petiole length, axillary budLength, leaf density, phyllotaxis ratio） of9species of Salix （Salix gracilistyla, Salix babylonica,Salix matsudana, Salix viminalis, Salix integra, Salix psammophila, Salix JiangsuensisCL.‘172’, Salix Jiangsuensis CL.‘799’, Salix babylonica×Salix fragilis）. It resulted thediscriminate function equation of the9species of Salix and constructed identification model,then put morphological indexes data of the9species of Salix into the correspondingidentification model to test its discriminate results. The results indicated that precision of the9species of Salix recognition was higher than95%.更多还原