The clonal growth characteristics of Zoysia japonica in response to the levels and orders of habitat resource gradient were studied in the current experiment. The treatments consisted of high, low nutrient level gradients, and a whole range nutrient level gradient; every gradient consisted of a series of micro-habitats whose nutrient level increased or decreased, respectively. The results showed that the total biomass of Z. japonica clones changed with the gradient in the following order: high nutrient level gradient>low nutrient level gradient>whole range nutrient level gradient, and in every nutrient level gradient. The total biomass of Z. japonica clone was higher at decreasing order habitat than that at increasing order habitat, which suggested that both increasing the nutrient level in habitat and matching the nutrient supply in a micro-habitat with the growth requirement of each ramet could significantly improve the clonal growth of Z. japonica . The ratios of root/shoot of Z. japonica changed with the gradient in the following order: low nutrient level gradient>whole range nutrient level gradient>high nutrient level gradient, which suggested that the ramets of Z. japonica tended to be independent, and plastically responded to each micro-habitat and less affected by the neighbor ramets within the clone. In every gradient and habitat with various nutrient level and order, the growth of ramet A was superior to ramets B. The biomass allocation in the stolon was the largest in the whole range nutrient level gradient habitat whose total nutrient was at moderate level. The response of clonal growth of Z. japonica to the levels and orders of habitat resource gradient reflected the adaptation of its morphological plasticity.

以克隆植物结缕草( Zoysia japonica )为研究对象,探究了其克隆整合的生长收益对生境资源梯度水平和次序的响应。试验设置了高养分水平、低养分水平和高低水平贯通3个梯度,且在每个梯度内设置养分浓度呈增长和降低次序的两类生境。结果表明,结缕草总生物量在高养分水平梯度生境>低养分水平梯度生境>高低水平贯通梯度生境,且在同一梯度降低次序生境的总生物量均高于增长次序生境,表明提高生境中的养分水平能显著增加结缕草克隆整合的生长收益,当小生境养分供应与分株生长的需求相匹配时,结缕草克隆整合的生长收益更大。根冠比在低养分水平梯度生境>高低水平贯通梯度生境(相当于中等养分水平)>高养分水平梯度生境,表明结缕草克隆分株具有较强的独立性,分株倾向于在自身所处小生境内发生可塑性反应,而受相邻分株的影响不大。在不同养分水平梯度和次序生境中,结缕草植株A分株的生长明显优于B分株的。对匍匐茎的生物量投资比例在高低养分水平贯通梯度生境(相当于中等养分水平)中最大。结缕草克隆生长对于生境资源梯度水平和次序的响应反映了其形态可塑性的生态适应意义。

To further explore the water regulation mechanism of clonal plant and its effects on carbon assimilation and excitation energy distribution under water stress, the pair of strawberry (Fragaria×ananassa) ramets was utilized (the elder ramet was referred as mother and the other as daughter), in which the stolons between ramets was either cut (unconnected group) or left intact (connected group). At first, the daughter ramet in each pair was well watered and the mother ramet was exposed to soil water deficit. Four days later, the connected group was further subdivided into two groups, and part irrigated daughters were continually watered, and the other daughters began to suffer from soil water shortage gradually. Our results reveal that soil drying caused leaf dehydration in mother ramets and significantly decreased its photosynthetic rates and stomatal conductance. The well-watered daughter ramets in connected groups alleviated the water stress in mother ramets effectively. When the well-watered daughter ramets in the connected group began to dry gradually, the water stress of their connected mother ramets was significantly aggravated. Water uptake of stressed mother ramet was dependent on the decrease in water potential and enhancement of osmotic adjustment of its own. Though soil drying resulted in a substantial accumulation of ABA in water stressed ramets, but there was no ABA increasing in connected ones. And the stomatal conductance had the similar changing tendency with leaf ABA content. Accordingly, we concluded that: (1) Water translocation between the connected ramets may be determined by the gradients in water potential; (2) ABA produced in water-stressed ramet could not be delivered to the adjacent and connected ramet and affect its stomatal behavior; (3) Under heterogeneous wet conditions, water physiological integration between clonal ramets would significantly improve the carbon assimilation of entire clonal system and excited energy utilizing efficiency of PSⅡ.

以盆栽草莓(Fragaria×ananassa)为材料研究了水分胁迫下克隆植物草莓母株和子株间的水分调控机制及其与碳同化、光系统Ⅱ激发能分配的关系。实验材料分为匍匐茎连接和剪断两个大组，进行两步实验。第1步实验，对连接组和剪断组的所有母株控水，子株充分供水；4d后进入第2步实验，把连接组分为两小组，对其中一组充分供水子株开始控水，另一组保持不变。结果表明，土壤干旱引起母株叶片失水，并使其净光合速率和气孔导度显著降低。但是连接组中供水良好的子株能有效缓解缺水母株的水分胁迫。当供水良好的子株也开始受到干旱处理的时候，则会加剧与之相连母株的水分胁迫。受胁迫母株可以通过加强渗透调节能力和降低水势从相连子株获取水分。虽然土壤干旱会造成受胁迫母株叶片脱落酸（abscisic acid, ABA）含量的大幅度增加，但是与之相连子株的叶片ABA含量并没有增加；并且气孔导度与ABA变化趋势一致。(1)草莓母株和子株间的水分运输是由二者的水势差驱动的；（2）ABA不会通过匍匐茎在母株和子株间传递并影响相邻子株气孔导度；（3）在水分异质性较大情况下，生理整合可明显提高克隆系统的碳同化能力和光系统Ⅱ激发能利用效率。

Aims A pot experiment to examine the effects of clonal integration on growth of the stoloniferous herb Centella asiatica suffering from heterogeneous heavy metal Cd 2+ stress was conducted to address two questions: (1) does clonal integration alleviate the negative effects on growth of clonal plants suffering from heterogeneous heavy metal stress; and (2) do the ramets growing in unfavorable microhabitats incur increased photosynthetic efficiency in the connected ramets? Methods Relatively young, distal ramets of C. asiatica were assigned to normal or Cd 2+ stressed soil, and the stolon connections between the relatively old proximal ramets and the young distal ramets were either severed or left intact. The net photosynthetic rate ( P n ), chlorophyll fluorescence (maximum quantum yield of PSII, F v / F m ) and chlorophyll contents of distal ramets and P n of proximal ramets were measured. The growth performance of distal and proximal ramets was investigated at the end of the experiment. Important findings Cd 2+ stress treatment significantly decreased the P n , F v / F m , chlorophyll contents and growth of distal ramets. Clonal integration significantly alleviated the negative effect of Cd 2+ stress to distal ramets in terms of P n , F v / F m , chlorophyll contents and biomass of distal ramets. There was no significant cost to the connected proximal ramets, and clonal integration did not incur increased photosynthetic efficiency in the proximal ramets. In addition, clonal integration significantly decreased root to shoot ratio of distal ramets suffering from Cd 2+ stress, and reduced the uptake of the heavy metal. Petiole length of proximal and distal ramets was not significantly affected by stolon severing and Cd 2+ stress. It is suggested that clonal integration may enhance growth of clonal plants suffering from heterogeneous heavy metal stress.

采用盆栽试验研究了异质性重金属镉胁迫下, 克隆整合对匍匐茎草本植物积雪草( Centella asiatica )生长的影响。将远端分株(相对年幼的分株)分别置于对照和镉胁迫处理下, 并对远端分株与近端分株(相对年长的分株)之间的匍匐茎进行切断或保持连接处理。研究结果显示: 镉胁迫处理显著降低了积雪草远端分株的净光合速率( P n )、最大光量子产量( F v / F m )、叶绿素含量、叶面积、分株数和生物量; 克隆整合缓解了镉胁迫对远端分株生长的不利影响; 克隆整合不仅未导致相连近端分株的损耗, 而且相连近端分株的光合效率也没有表现出补偿性增加; 克隆整合降低了远端受胁迫分株的根冠比, 从而使之减少了对土壤中重金属镉的吸收; 匍匐茎切断和镉胁迫处理对近端分株、远端分株的叶柄长没有显著的影响。结果表明: 克隆整合提高了积雪草遭受镉胁迫的远端分株的生长, 改变了其生物量分配格局, 并有助于整个克隆片段在异质性重金属胁迫下的生长。该研究对于丰富和发展异质性环境胁迫下克隆整合的生态适应对策具有重要意义。

Clonal integration, allowing resource to be shared between ramets, is a unique biological characteristic for clonal plants. Ramets of stoloniferous and rhizomatous species internally translocate resources from sites of high supply to sites of high demand via physical connections among them, resulting in enhanced performance of ramets and/or ramet system under environmental stresses. On the other hand, environmental stresses always induce accumulation of reactive oxygen species (ROS), which attack membrane integration, deactivate protein function and subsequently interrupt normal metabolism process. Although there is a large body of knowledge on how clonal integration improves the performance of clonal plants, its effect on the activity of enzymes responsible for scavenging ROS, remains unknown. Here we investigated the influence of clonal integration on ROS of Cynodon dactylon ,a stoloniferous clonal herb commonly found in riparian areas of reservoirs, subjected to waterlogging stress. Clonal fragments with 4 ramets were placed in pots divided into 2 chambers. The 2 apical (relatively younger) ramets of each fragment were submerged in water at depth of 0(control) or 15 cm, with the stolons connecting to the basal (relatively older) ramets under normal condition either severed (preventing clonal integration) or not (allowing integration). The activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) from root tissue of apical and basal ramets of C. dactylon were measured. Meanwhile, the biomass of apical and basal ramets after 20 days' treatments was also measured to investigate whether clonal integration executed "enhancing effect" on performance of C. dactylon . Compared to 41.4% reduction of apical biomass under connection and waterlogging treatment, severing significantly decreased apical biomass by 58.8% under waterlogging stress, suggesting that clonal integration could improved the performance of apical ramets of C. dactylon . However, such effect was not found in terms of basal biomass. Under waterlogging stress, physical connection greatly increased root SOD activity of apical ramets up to control level, while disconnection significantly decreased it to 41.7% of the value of the control treatment. Furthermore, disconnection combined with waterlogging treatment also drops root APX and CAT activity of apical ramets to some extents. On the other hand for basal ramets, physical connection induced significant reduction of root SOD and CAT activities to 35.8% and 51.3% of the control level under waterlogging stress. These results illuminated that clonal integration could ameliorate the balance between regeneration and scavenging of reactive oxygen species under waterlogging stress imposed to apical ramets, which probably was one of the key biochemical processes responsible for the enhanced performance of clone plants. To our knowledge, this is the first report that clonal integration affects the activities of SOD, APX, and CAT, the three key enzymes responsible for scavenging reactive oxygen species which would commonly accumulate and subsequently interrupt plants' normal metabolism under environmental stresses. Therefore, we suggested that clonal integration could not only adjust anatomic/structural/physiological processes, but also ameliorate the balance between regeneration and scavenging of reactive oxygen species, to improve the performance of stressed ramets. Furthermore, we also thought that resource transport between apical and basal ramets was the main mechanism attributed to the variation of ROS scavenging enzyme activity.

虽然国内外已开展大量关于克隆整合影响植物抗逆生理的研究,但迄今未见克隆整合是否会影响逆境下不同分株清除活性氧过程的报道。以河岸带适生克隆植物狗牙根( Cynodon dactylon )为例,研究克隆植物的抗氧化生理响应,检测了狗牙根在先端淹水/不淹水、先端与基端匍匐茎连接/切断两个因素的交互作用下的根部主要抗氧化酶:超氧化岐化酶(Superoxide dismutase, SOD)、抗坏血酸过氧化物酶(Ascorbate peroxidase, APX)、过氧化氢酶(Catalase, CAT)的活力以及生物量的变化。结果显示,淹水环境中狗牙根先端的生物量和根部SOD酶活力在匍匐茎连接处理下显著高于切断处理组,同一处理的生物量以及根部APX、CAT酶活力总体上表现出不同程度的提高趋势;与受淹先端连接的基端分株根部抗氧化酶活力均低于切断处理组,且SOD和CAT受连接处理影响显著;淹水和切断处理显著降低先端分株的生物量,但对基端和克隆片段影响不明显。这表明淹水胁迫下克隆整合提高了其根部活性氧清除能力,显著改善了先端分株的表现。

Results of the study on available nutrients to linked two-ramets of buffalograss (Buchloë dactyloides) indicate that the first-growing ramets are benefited immensely from the next-growing ramets, but the latter are not repaid by the former which are the unidirectional beneficiary. The root biomass and height of the later-growing ramets apparently rise faster than those of the earlier-growing ramets. Contrarily, the tiller node biomass, 1 st stolon biomass, 1 st stolon node number, and 1 st stolon length of the first-emerging ramets grow quicker than those of the later-growing ramets. However, the next-growing ramets can be benefited from the first-growing ones in the tiller node biomass and the longest 1 st stolon.

野牛草分株对养分异质性反应的研究表明:姊株能显著地从妹株分株生物量获益,但妹株并不能从姊株获益,属于单向获益;妹株株高、根系生物量显著地比姊株增长快;姊株1级匍匐茎总长、总节数、生物量及分蘖节生物量显著比妹株增长快;妹株能显著从姊株最长1级匍匐茎和分蘖节生物量获益。

碳素整合是克隆植物生理整合过程中非常重要的一部分,是克隆植物生存、生长、繁殖的物质基础.克隆植物碳素整合的基本机制具有一定的共同性或相似性,但克隆植物的种类不同、所处生境以及发育阶段不同或所受到的干扰、胁迫的程度不同,其碳素整合的范围、强度、方向、过程等也有所差异.本文对克隆植物碳素生理整合的基本特征、生态效应以及主要的影响因素进行了详细分析,并对迄今有关克隆植物碳素整合的最新研究进展进行了系统总结.同时,对碳素整合的主要研究方法进行了评价与展望,认为在今后研究中,应加强对克隆植物碳素整合的遗传学基础的研究,同时对于碳素整合的生理学、解剖学和生态学机制的研究也亟待深入.参65

Bromus inermis Leyss. is a dominant rhizomatous grass in the Otindag Sandland of North China, where the environment is heterogeneous, and non-saline, low-saline, and high-saline patches form a mosaic of habitats. Ramets of B. inermis simultaneously inhabit many patches at different salinity levels. We hypothesized that clonal fragments in high- saline patches benefit from clonal integration. A factorial greenhouse pot experiment with salinity and rhizome- severing as main effects was conducted in which each clonal fragment consisted of two interconnected ramets. In one treatment, the proximal part of the clonal fragment received a salt treatment (300 mmol/L NaCl solution), and in another treatment the distal part received a salt treatment. Rhizome connections between neighboring ramets were severed or left intact. Rhizome severing dramatically decreased survival of salt-treated ramets. A cost-benefit analysis based on biomass production, number of shoots, number of rhizome nodes, and total rhizome length showed that untreated ramets supported connected ramets treated with salt by clonal integration but did not incur any cost from resource export. We speculate that clonal integration may be an important adaptation of B. inermis to heterogeneous saline environments that increases its growth and survival, and thus fitness, in semiarid sandy lands.

无芒雀麦是浑善达克沙地植物群落中占优势的多年生根茎禾草。研究了克隆整合特性对无芒雀麦在异质性盐分环境中存活和生长的影响。结果表明，克隆整合显著提高了无芒雀麦分株在高盐环境中的存活能力，耗-益分析表明无芒雀麦在高盐斑块中分株的生物量、分株数、根茎节数和根茎总长显著受益于克隆整合，而与之相连的非盐分斑块中的分株却没有产生显著的损耗。因而，克隆整合特性是无芒雀麦对异质性环境形成的重要适应对策，它使无芒雀麦能够扩展到不适合植物生长的高盐分斑块中，从而增加了无芒雀麦在浑善达克沙地中的存活和生长，提高了其在半干旱沙化地区的适合度。

Phenotypic responses of ramets of the stoloniferous clonal plant Buchloe dactyloides in homogeneous nutrient and under three scales of heterogeneous nutrients were studied by measuring the growth, morphological characters of clonal ramets and the chlorophyll fluorescence characteristics of mother ramets. Compared with other nutrient treatments, the number of ramets, clumps and stolons, biomass, F v / F m and Φ PSⅡ were higher in plots of heterogeneous nutrient at 25 cm×25 cm spacing. However, different nutrient conditions did not prompt significant differences in internode and root length. These results suggested that physiological integration modifies phenotypic plasticity of clonal ramets for efficient absorption and utilization of nutrients, and increases the chlorophyll fluorescence of mother ramets in heterogeneous nutrient. These effects were more pronounced when the spacing was 25 cm×25 cm.

本实验以匍匐茎型克隆植物野牛草为材料,通过测定其在同质营养和3个斑块尺度的异质营养条件下生长指标、形态指标和叶绿素荧光参数的变化,研究野牛草对异质营养的表型可塑性反应。野牛草在尺度为25 cm×25 cm异质营养条件下会产生更多的分株、丛和分枝,积累更多的生物量,具有较高的 F v / F m 和 Φ PSⅡ ,生长状况要好于其他营养条件,但根系长度和间隔子长度并没有明显的变化。结果表明,生理整合调控了野牛草的表型可塑性,提高了母株的叶绿素荧光特性,增加了克隆分株对养分的吸收、利用能力,使野牛草在异质营养条件下的生长状况好于同质营养条件,特别是在尺度为25 cm×25 cm的异质营养条件下效果更为明显。