大气CO2浓度升高对红桦碳水化合物含量和分配的影响

碳水化合物按其存在的形式可分为结构性碳水化合物和非结构性碳水化合物两种。前者主要用于植物体的形态建成；后者是参与植物生命代谢的重要物质。迄今为止，有关CO2浓度升高对植物叶片中的碳水化合物含量的研究较多，而对其它器官中碳水化合物含量以及碳水化合物在植物体内的分配响应研究较少。碳水化合物含量在植物各器官中的变化能够反映光合同化产物在叶和茎、枝和根中的转运情况；碳水化合物的分配与植物的生长模式相关，它的变化会对植物的生长情况产生影响。因此，为全面认识植物生理生化与生长过程对大气CO2浓度升高响应情况，需要对CO2浓度升高条件下植物体内碳水化合物的含量及分配变化进行深入的研究与探讨。本文应用自控、独立、封闭的生长室系统，研究了红桦幼苗根、茎、叶和枝的碳水化合物含量以及分配格局对大气CO2浓度升高(环境CO2浓度+350 µmol·mol-1) 的响应。研究结果表明：1) CO2浓度升高使红桦幼苗叶片中的非结构性碳水化合物含量显著增加。这可能会对光合作用造成反馈抑制，降低光合速率。2) CO2浓度升高使红桦幼苗根、茎和枝中的还原糖、蔗糖、总可溶性糖、淀粉和总的非结构性碳水化合物(TNC) 含量显著增加。说明CO2浓度升高促进了碳水化合物由叶片向枝、茎和根中的运输转移，支持了Finn和Brun的假设。3) 在总的非结构性碳水化合物(TNC) 中，淀粉所占比例最大。同样地，CO2浓度升高使TNC含量增加的部分中，淀粉所占的比例也最大。在叶片、枝、茎和根中淀粉含量增加部分占TNC含量增加部分的91.45%、88.23%、83.23%和82.01%。4) CO2浓度升高使红桦幼苗根、茎、叶和枝内的纤维素含量有增加的趋势，但未达到显著水平。需要进一步研究长期CO2浓度升高下，纤维素含量的响应程度。5) CO2浓度升高使碳水化合物在红桦幼苗体内的分配发生了改变。红桦幼苗体内碳水化合物分配变化的一致趋势是由地上部分向地下部分分配转移。其中，测定的所有碳水化合物均向根中分配增多。同时，CO2浓度升高使红桦幼苗的根冠比显著增大；根系干重显著增加。这些结果支持了Gorissen 和Cotrufo的假设，即碳水化合物向根中分配增多是根冠比增大的主要原因。6) CO2浓度升高使红桦幼苗体内的氮含量显著下降。氮含量的下降可能主要是由生长的加快和TNC (主要是淀粉) 含量的增加对氮的稀释造成的。Carbohydrates found in plants are frequently grouped into two different classes:structural carbohydrates and non-structural carbohydrates. The former mainlyconstruct the plant basic framework, while the latter are essential for plant growth andmetabolism. As yet there is lack of information on the effects of elevated CO2concentration on carbohydrate contents in stem, branch and root of plant, and oncarbohydrate allocation in organs of plant although there have been many reports onthe responses of carbohydrate contents to elevated CO2 concentration in plant foliages.A shift of carbohydrate contents in plant reflects a change in transporting ofphotosynthetic production from leaf to stem, branch and root of plant. The allocationof carbohydrates that is correlated to plant growth patterns affects plant growth. Thus,in order to understand the influences of elevated CO2 on biochemical process,physiological change and plant growth well, the response of carbohydrate contentsand allocation in plant to elevated CO2 should be further investigated. In our study, theeffects of elevated CO2 on carbohydrate contents and their allocation between leaf,stem, branch and root tissue of Betula albosinensis seedlings were determined. Theseedlings were grown in independent and enclosed-top chambers. Chambers werecontrolled to reproduce ambient (CK) and ambient + 350 µmol·mol-1 CO2 (EC)concentration for 1 year. The results here showed that,1) Elevated CO2 significantly increased non-structural carbohydrate contents in leafof red birch seedlings. This will reduce photosynthetic rate.2) Elevated CO2 also significantly increased non-structural carbohydrate contentsin root, stem and branch of red birch seedlings. These findings supported thehypothesis that elevated CO2 accelerated carbohydrates from leaf to branch, stem androot.3) Starch makes up the largest parts of total non-structural carbohydrate. In thesame way, the increase of starch plays a main role in the increase of totalnon-structural carbohydrate under elevated CO2. In leaf, branch, stem and root, theincrements of starch contents comprised 91.45%, 88.23%, 83.23% and 82.01% of theincrements of total non-structural carbohydrate contents.4) Under elevated CO2 the cellulose contents have an increasing tendency in redbirch seedlings. It is needed to investigate the effects of long-term elevated CO2 oncellulose contents in plant.5) There are significant CO2 effects on the allocation of carbohydrate in organs ofred birch seedlings. Under elevated CO2 more carbohydrates were allocated to root.Moreover, CO2 enrichment significantly increased the root to shoot ratio of red birchseedlings and the dry weight of roots. These results supported Gorissen and Cotrufo ‘shypothesis that increase of carbohydrate allocation to root mostly contributed to theincrease of root to shoot ratio.6) Elevated CO2 brought about a reduction in the nitrogen contents of leaf, stem,branch and root. The decline of nitrogen contents under elevated CO2 is mainlycaused by the dilution effects of increasing starch level and growth of red birchseedlings.

遮荫与外源脱落酸喷施对青杨(Populus cathayana Rehd.)不同种群抗旱性的影响

杨树具有分布广、适应性强的特征，在生态环境治理和解决木材短缺方面均占有重要位置。青杨(Populus cathayana Rehd.)是青杨派树种的重要成员之一，也是生长较迅速、易繁殖的重要杨树资源。本研究选取了来自不同气候地区的青杨两种群为材料，采用植物生态学、生理学和生物化学的研究方法，系统地研究了青杨对干旱与遮荫、干旱与外源脱落酸(ABA)喷施的生长、形态、生理和生化响应及种群间差异，研究成果可为我国干旱半干旱地区的造林以及生态恢复提供理论依据和科学指导。主要研究结论如下：1.青杨在干旱胁迫下的适应机制为：生长性状及生物量的分配变化：干旱胁迫下虽然植株生长受抑，株高、基茎及各部分生物量都显著减小，但有相对较多的生物量向根部分配，根/冠比以及细/粗根比增加。青杨对干旱胁迫的光合作用表现为：干旱胁迫降低了青杨的净光合速率、蒸腾速率、气孔导度以及光合氮利用效率，提高了瞬时用水效率。干旱还引起了活性氧的产生，使得膜脂过氧化产物丙二醛(MDA)增加，同时也增强了植物抗氧化酶系统(如超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性的增加)及非酶系统的能力(如抗坏血酸(AsA)含量的增加)。干旱降低了植物叶片的相对含水量，而促进了渗透调节物质(游离脯氨酸及可溶性糖)的积累，增加了植物的渗调能力。干旱下青杨两种群的内源ABA含量显著增加，碳同位素组分(δ13C)也显著提高。这些结果证明植物遭受干旱胁迫后发生一系列的形态、生理和生化响应，这些变化能提高植物在干旱下的存活和生长能力。2.青杨两种群对干旱胁迫反应的种群差异：与来自湿润地区的汉源种群相比，来自干旱地区的乐都种群在干旱条件下生物量向根系分配的可塑性更强，同时具有更强的抗氧化系统能力，所受到活性氧的伤害也更少，并且累积更多的脯胺酸和ABA，具有更高的δ13C。这些都说明了乐都种群对干旱的适应性比汉源种群更强。两种群对干旱的响应差异应归于它们的用水策略的不同：汉源种群来自湿润地区，采用了耗水型的用水策略，抗旱能力较弱；而乐都种群，来自干旱地区，通常采用节水型的用水策略，有更强的抗旱能力。3.遮荫对青杨两种群抗旱性的影响：遮荫对青杨抗旱性的影响决定于遮荫程度的不同，我们的结果表明中度的遮荫可以有效的提高干旱下植物的生长，对干旱胁迫有明显的缓解作用，具体体现在中度遮荫下受旱植物的叶片相对含水量得到提高，使得植物体内水分状况得到了改善；光合速率并未降低，植物光合氮利用效率增加，说明中度的遮荫并未明显限制植物的碳获得；抗氧化酶活性与膜脂过氧化产物MDA含量的同时降低，说明中度遮荫下所受到的活性氧伤害减少；中度遮荫下的ABA及δ13C的变化也不如在全光下变化明显，这也说明中度遮荫缓解了干旱胁迫。但是重度的遮荫却对干旱胁迫有明显的加剧作用，主要表现在重度遮荫降低了植物的光合速率，严重抑制了植物的生长；同时重度遮荫下脯胺酸含量和抗氧化酶活性的急剧下降，导致了植物渗调能力的下降及膜脂过氧化产物MDA的显著升高；重度遮荫还显著降低了内源ABA的累积和δ13C，降低了植物的抗旱能力。此外，青杨两种群在对干旱和遮荫的响应中，也表现出种群差异。汉源种群，来自湿润且年日照辐射较少的地区，表现出相对更强的耐荫性和需水性。而乐都种群，来自干旱且年日照辐射丰富的地区，表现出相对更强的耐旱性和需光性。这说明了植物对环境胁迫的耐受性是其长期适应原生境的结果，并且来自不同气候地区的两种群在面临环境胁迫时会采取不同的生存策略。4. 外源ABA喷施对青杨两种群抗旱性的影响：外源ABA的喷施可以提高两种群的抗旱性，具体表现为外源ABA喷施促进了青杨根系的生长，显著提高了干旱下植物的根/冠比和细/粗根比，减少了比叶面积；在生理生化方面，外源ABA降低了干旱下植物叶片的气孔导度，降低了蒸腾速率和净光合速率，但提高了瞬时用水效率，提高了叶片的相对含水量，增加了干旱下植物的保水能力。外源ABA进一步增加了干旱下植物内源ABA的积累，促进了植物渗调物质如脯胺酸和可溶性糖的积累，增加了抗氧化酶系统(如SOD、APX、CAT)的活性和非酶系统AsA的含量，降低了活性氧(如超氧阴离子(O2和过氧化氢(H2O2))对植株的伤害。此外，外源ABA还进一步提高了干旱下植物的δ13C，提高了植物的长期用水效率，由此提高了植物的抗旱能力。另一方面，两种群对外源ABA和干旱的响应也有所差别。来自湿润地区的汉源种群，对干旱较为敏感，所受干旱的影响也较大，而外源ABA的喷施对汉源种群抗旱性的提高作用也更为突出。乐都种群，由于其长期适应干旱地区的生长，本身已具有较强的抗旱能力，因此外源ABA喷施对其抗旱性的提高不如对汉源种群的效果明显。由此我们可以得出对于一些抗性弱或干旱敏感的物种或者种群，可以采用外施ABA的方法来提高其抗性。Poplars play an important role in lumber supply, and are important component ofecosystems due to their wide distribution and well adaptation. Populus cathayana Rehd.,which belongs to Populus Sect. Tacamahaca Spach, is one of the most important resources ofpoplars for its fast growth and reproductive. In this study, different populations of P.cathayana were used as experiment material to investigate the adaptability to drought stressand population differences in adaptability, and the effects of shade and exogenous abscisicacid (ABA) application on the drought tolerance. Our results could provide a strongtheoretical evidence and scientific direction for the afforestation, and rehabilitation ofecosystem in the arid and semi-arid area, and provide a strong evidence for adaptivedifferentiation of different populations, and so may be used as criteria for species selectionand tree improvement. The results are as follows:1. A large set of parallel response to drought stress: Drought stress caused pronouncedinhibition of the growth and increased relatively dry matter allocation into the root. For thetwo populations, the shoot height, basal diameter and total biomass were decreased but theroot/shoot ratio and fine root/coarse root ratio were increased under drought conditions；Drought stress caused pronounced inhibition of photosynthesis, decreased the stomatalconductance, transpiration rate, and photosynthetic nitrogen-use efficiency (PNUE) butincreased the instantaneous water use efficiency. Drought significantly improved the levels ofreactive oxygen species and malondialdehyde (MDA) and to induce the entire set ofantioxidative systems including the increase of activities of superoxide dismutase (SOD),ascorbate peroxidase (APX), catalase (CAT) and ascorbate (AsA) content. Drought decreased the leaf relative water content (RWC) but improved the capability of osmotic adjustmentindicated by the higher proline accumulation. Drought also increased the ABA content andcarbon isotope composition (δ13C), which indicating the long period water use efficiency wasimproved under drought. These results demonstrate that there are a large set of parallelchanges in the morphological, physiological and biochemical responses when plants areexposed to drought stress; these changes may enhance the capability of plants to survive andgrow during drought periods.2. Difference in adaptation to drought stress between contrasting populations of P.cathayana: Compared with the Hanyuan population (wet climate), the Ledu population (dryclimate) showed higher root/shoot ratio and water use efficiency, exhibited higherantioxidative systems capability thus resulting in less oxidative damage, accumulated moreABA and free proline content under drought conditions. The results suggested that there weredifferent water-use strategies between the two populations. The Ledu population, whichcomes from dry climate region, with higher drought tolerance, may employ a conservativewater-use strategy, whereas the Hanyuan population, which comes from wet climate, withlower drought tolerance, may employ a prodigal water-use strategy. These variations indrought responses may be used as criteria for species selection and tree improvement.3. The effects of shade on the drought tolerance: The reduction in the availability of lightand water affected the morphological and physiological responses of the two P. cathayanapopulations. In addition, the light environment modified the growth responses of P.cathayana seedlings to varying water environments in different ways depending upon theintensity of the light levels considered. There is an apparent alleviation to drought effects bymoderate shade in P. cathayana seedlings, as indicated by the higher leaf RWC, and unchanged net photosynthesis and PNUE, as well as by the lower antioxditative enzymeactivity, MDA, ABA and δ13C levels, which implied moderate shade did not significantlylimited the carbon acquisition or inhibited the plant growth, but ameliorated the detrimentaleffects of drought. On the other hand, an apparent aggravation to drought effects by severeshade was also observed, as indicated by the pronounced decrease of plant growth and net photosynthesis, the lower total biomass, ABA level, δ13C, free proline content andantioxditative enzyme activity and higher MDA accumulation. By contrast, the twopopulations showed different responses to shade and drought. The Hanyuan population,which comes from a riparian basin having a relatively wet climate and less annual solarradiation, is more sensitive to drought but more tolerant to shade. The Ledu population, whichcomes from a mountainous plateau with less rainfall and with more annual solar radiation, ismore tolerant to drought but more sensitive to shade. The results demonstrated that theendurance of plants to stress is a result of long-term evolution and adaptation to theenvironment, as suggested by the different strategies employed by the P. cathayanapopulations originating from contrasting habitats when they were exposed to drought andshade.4. The effects of exogenous ABA application on the drought tolerance: For bothpopulations under drought conditions tested, exogenous ABA application significantlyimproved the root/shoot ratio, fine root/coarse root ratio, and decreased the specifical leaf area.On the physiological and biochemical traits, exogenous ABA application significantlydecreased stomatal conductance, transpiration rate and net photosythesis but increased theinstance water use efficiency and leaf RWC. On the other hand, exogenous ABA applicationsignificantly increased endogenous ABA, proline, solube sugar and AsA content, as well asSOD, APX and CAT activities, thus reduced the damage of reactive oxygen species. Moreover,the long period water use efficiency as indicated by δ13C was also improved by exogenousABA application. In additionally, there was different responsive between the two populationsto drought and exogenous ABA application. The Hanyuan population, which comes from wetclimate region, is more sensitive to drought, and the effect of exogenous ABA is moreobviously than that in the Ledu population, which comes from dry climate region and is moredrought-responsive. Therefore, we can use exogenous ABA application to improve theresistance of plants, especially for the drought- sensitive species or populations.

克隆植物东方草莓对异质生境的适应对策

克隆植物被认为比非克隆植物更宜于利用异质性环境。在复杂的空间异质环境中，克隆植物可能形成了各种有效利用环境异质性的适应对策。对于克隆植物适应机制的研究，前人已做了大量的工作，特别是从形态和生物量分配等方面对简单异质生境下克隆植物的克隆整合和克隆分工进行了详细的研究。本研究以分布广泛的克隆植物东方草莓（Fragaria orientalis）作为研究对象，应用野外调查和实验生态学方法，采用多对比度单资源模型和不同向双资源模型，从形态和生理生态的角度，研究复杂异质生境下克隆植物的整合和分工及其耗益问题，分析不同类型的生境对克隆植物整合和分工的修饰作用，进而探讨克隆植物对异质生境的适应策略。克隆构型和分株种群特征是植物克隆生长及其生态适应对策研究的基本内容。本文通过野外调查，研究在不同光照条件下东方草莓克隆构型、分株种群特征以及点分布格局。结果表明：东方草莓的克隆构型随光照发生相应的变化，低光照下其匍匐茎节间长和分枝角度均增大而分枝强度减小；随光照减弱，东方草莓分株种群的生物量、根冠比和分株种群密度显著降低；不同光照下东方草莓分株均以随机分布为主但不同尺度下有所差异，其分布格局强度依次为旷地<林缘<林下。结合克隆植物对资源的利用对策，探讨了克隆构型和分株种群特征以及分布格局随环境条件变化的生态适应意义。不同生境斑块条件下克隆植物可能采取不同的适应对策。采用盆栽实验，研究不同水分对比度下克隆整合及其生理生态特征，并对单向和交互资源中东方草莓的克隆整合做了对比研究。结果显示：高的水分对比度能够促进东方草莓的克隆整合，并能刺激相连分株增加光合作用，东方草莓体内的氧化—抗氧化系统也II随对比度做出相应的反应。耗-益分析表明胁迫分株的受益是以供给分株的损耗为代价的，但从克隆片段总体来说是受益的。单向资源中东方草莓生长的绝对值高于交互资源，但耗-益分析表明生长于交互资源下东方草莓的克隆整合获益大于生长于单向资源下东方草莓的克隆整合获益。长期生长于特定生境的克隆植物，在进化过程中其克隆整合和克隆分工在对资源异质性的适应策略方面可能有所侧重。采用盆栽实验对来自不同海拔梯度的东方草莓的克隆整合和克隆分工对异质资源的适应对策进行了研究。实验结果表明，来自高海拔的东方草莓可塑性较差。来自两个海拔的东方草莓对切断匍匐茎的表现有所差异，总体上切断匍匐茎对来自高海拔的东方草莓影响更大些。另外，来自高海拔的东方草莓表现出更高的克隆分工。IIIClonal plants are known to be more suitable for the habitats of heterogeneousresources than nonclonal plants, perhaps due to their well developed adaptivestrategies to environmental heterogeneity. Many studies have been done on theadaptive mechanisms of clonal plants, especially on the clonal integration anddivision of labor with morphology and biomass allocation under simpleheterogeneous habitats. Based on field surveys, laboratory experiments, multi-contrastunidirectional resource model and reciprocal resource model, Fragaria orientalis, aRosaceae stoloniferous herb that widely distributes in China, was used to study thisplant’s morphological and physiological responses to complicated heterogeneoushabitats in terms of its clonal integration, division of labor and cost-benefit, as well astheir modifications by different habitats, so as to better understand the adaptivestrategies of clonal plants under heterogeneous environments.Clonal architecture and ramet population characteristics are of the major concernin the studies on growth and adaptive strategies of clonal plants. Clonal architecture,ramet population characteristics and spatial point pattern of F. orientalis underdifferent light intensity were studied with field observations. The results showed that,clonal architecture changed with light availability: Internode-lengths and branchangels of stolons were larger while branch intensities were smaller under lower lightintensity than those under higher light intensity; Biomass of ramet population,root-shoot ratio and density of ramet population decreased significantly with reduce oflight intensity; Under all light intensities, spatial pattern of ramets was mainlyrandomly distributed but it changed with different scales, with pattern intensity as:open space < forest edge < understory. Adaptation significance of the clonal architecture, the ramet population characteristics and the spatial pattern changing withdifferent environments was discussed according to these results.Clonal plants may take different adaptive strategies under different patches. Withpot culture, clonal integration and physiological parameters of F. orientalis underdifferent water contrasts were studied, and clonal integration under unilateralresources and reciprocal resources were also compared. The results suggested that,high water contrast improve the clonal integration of F. orientalis and increase thephotosynthesis of connected ramets. Oxidative and antioxidative system of F.orientalis also responded with changing water contrasts. According to cost-benefitanalysis, the drought-stressed ramets obtained benefits from the connectedwell-watered ramets, and as a whole, the clonal fragment could also get benefits.Growth of F. orientalis in homogeneous resources was better than that inheterogeneous resources, but the whole plant got more benefit through clonalintegration in heterogeneous resources than in homogeneous resources.Pot culture experiments were also used to study the adaptive strategies inutilizing heterogeneous resources by the plant populations from different altitudes.The results showed that, F. orientalis from alpine zones were shorter and lessexpanded with poorer clonal plasticity than those from middle mountains. F.orientalis from two different altitudes showed different responses to stolon severing,and as a whole, stolon severing had more influence on F. orientalis from alpine zones.In addition, F. orientalis from alpine zones exhibited higher division of labor, whichsuggested that clonal plants from different habitats develop their own adaptivemechanisms in their clonal integration and division of labor in response toenvironmental heterogeneity.

干旱胁迫与施N条件下白刺花（Sophora davidii）幼苗生长及其适应机制

干旱环境常常由于多变的降水事件和贫瘠土壤的综合作用，表现出较低的生产力和较低的植被覆盖度。全球性的气候变暖和人类干扰必将使得干旱地区缺水现状越来越严竣。贫瘠土壤环境中已经很低的有效养分含量也将会随着干旱的扩大而越来越低。干旱与半干旱系统中不断加剧的水分与养分的缺失将严重限制植物的生长和植被的更新，必然会使得已经恶化的环境恶化速率的加快、恶化范围的加大。如何抑制这种趋势，逐步改善已经恶化的环境是现在和将来干旱系统管理者面临的主要关键问题。了解干旱系统本土植物对未来气候变化的适应机制，不仅是植物生态学研究的重要内容，也对人为调节干旱环境，改善干旱系统植被条件，提高植被覆盖度具有重要的实践意义。 本研究以干旱河谷优势灌木白刺花（Sophora davidii）为研究对象，通过两年大棚水分和施N控制实验和一个生长季野外施N半控制实验，从植物生长－生理－资源利用以及植物生长土壤环境特征入手，系统的研究了白刺花幼苗生长特性对干旱胁迫和施N的响应与适应机制，并试图探讨施N是否可调节干旱系统土壤环境，人工促进干旱条件下幼苗定居，最终贡献于促进植被更新实践。初步研究结论如下： 1）白刺花幼苗生长、生物量积累与分配以及水分利用效率对干旱胁迫和施N处理的适应白刺花幼苗株高、基径、叶片数目、叶面积、根长、生物量生产、相对含水量和水分利用效率随着干旱胁迫程度的增加而明显降低，但地下部分生物量比例和R/S随着干旱胁迫程度的增加而增加。轻度施N处理下幼苗株高、基径、叶片数目、叶片面积和生物量生产有所增加。但重度施N处理下这些生长指标表现出微弱甚至降低的趋势。严重干旱胁迫条件下，幼苗叶面积率、R/S、相对含水量和水分利用效率也以轻度施N处理为最高。 2）白刺花幼苗叶片光合生理特征对干旱胁迫和施N处理的适应叶片光合色素含量和叶片光合效率随着干旱胁迫程度的增加而显著降低，并且PS2系统在干旱胁迫条件下表现出一定程度的光损害。但是比叶面积随着干旱胁迫程度的增加而增加。在相对较好水分条件下幼苗净光合速率的降低可能是因为气孔限制作用，而严重干旱胁迫条件下非气孔限制可能是导致幼苗叶片光合速率下降的主要原因。叶片叶绿素含量、潜在光合能力、羧化效率、光合效率以及RUBP再生能力等在施N处理下得到提高，并因而改善干旱胁迫条件下光合能力和效率。虽然各荧光参数对施N处理并无显著的反应，但是干旱胁迫条件下qN和Fv/Fm在轻度施N处理下维持相对较高的水平，而两年连续处理后在严重干旱胁迫条件下幼苗叶片光合效率受到重度施N处理的抑制，并且Fv/Fm和qN也在重度施N处理下降低。 3）白刺花幼苗C、N和P积累以及N、P利用效率对干旱胁迫和施N处理的适应白刺花幼苗C、N和P的积累，P利用效率以及N和P吸收效率随干旱胁迫程度的增加而显著降低，C、N和P的分配格局也随之改变。在相同水分处理下，C、N和P的积累量、P利用效率以及N和P吸收效率在轻度施N处理下表现为较高的水平。然而，C、N和P的积累量和P利用效率在重度施N处理下不仅没有表现出显著的正效应，而且有降低的趋势。另外，在相同水分条件下白刺花幼苗N利用效率随着施N强度的增加而降低。 4）白刺花幼苗生长土壤化学与微生物特性对干旱胁迫和施N的适应白刺花幼苗生长土壤有机C、有效N和P含量也随干旱胁迫程度的增加而明显降低。干旱胁迫条件下土壤C/N、C/P、转化酶、脲酶和碱性磷酸酶活性的降低可能表明较低的N和P矿化速率。尽管微生物生物量C、N和P对一个生长季干旱胁迫处理无显著反应，但微生物生物量C和N在两年连续干旱胁迫后显著降低。土壤有机C和有效P含量在轻度施N处理下大于重度施N处理，但是有效N含量随着施N强度的增加而增加。微生物生物量C和N、碱性磷酸酶和转化酶活性也在轻度施N处理下有所增加。但是碱性磷酸酶活性在重度施N处理下降低。 5）野外条件下白刺花幼苗生长特征及生长土壤生化特性对施N的适应植物生长、生物生产量、C的固定、N、P等资源的吸收和积累、其它受限资源的利用效率（如P）在轻度施N处理下均有所增加，但N利用效率有所降低。幼苗生物生产量及C、N和P等资源的分配格局在轻度施N处理下也没有明显的改变。白刺花幼苗叶片数目、生物生产量和C、N、P的积累量在重度施N处理下虽然也相对于对照有所增加，但幼苗根系长度显著降低。生物量及资源（生物量、C、N、P）在重度施N处理下较多地分配给地上部分（主要是叶片）。另外，土壤有机C、全N和有效N含量随外源施N的增加而显著增加，土壤pH随之降低，但土壤全P含量并无显著反应。其中有机C含量和有效P含量以轻度施N处理最高。微生物生物量C、N和P在轻度施N处理下也显著增加，而微生物生物量C在重度施N处理下显著降低。同时，转化酶、脲酶、碱性磷酸酶和中性磷酸酶活性在施N处理下也明显的提高，但酸性磷酸酶和过氧化氢酶活性显著降低，其中碱性磷酸酶和中性磷酸酶活性以轻度施N处理最高。 综合分析表明，干旱河谷水分和N严重限制了白刺花幼苗的生长。施N不能完全改变干旱胁迫对白刺花幼苗的抑制的作用，但是由于施N增加土壤N有效性，改善土壤一系列生物与化学过程，幼苗的生长特性也对施N表现出强烈的反应，表现为植物结构与资源分配格局的改善，植物叶片光合能力与效率的提高，植物生长以及利用其他受限资源（如水分和P）的效率的增加，致使植物自身生长及其生长环境在干旱环境下得到改善。但是过度施N不仅不能起到改善干旱胁迫下植物生长环境、促进植物生长的作用，反而在土壤过程以及植物生长过程中加重干旱胁迫对植物的伤害。因此，建议在采用白刺花作为先锋种改善干旱河谷系统环境的实践中，可适当施加N以改善土壤环境，调节植物利用与分配资源的效率，促进植物定居，得到人工促进种群更新的目的。但在实践过程中也要避免过度施N。 Arid regions of the world are generally noted for their low primary productivity which is due to a combination of low, unpredictable water supply and low soil nutrient concentrations. The most serious effects of global climate change and human disturbances may well be those which related to increasing drought since drought stress has already been the principal constraint in plant growth. The decline in total rainfall and/or soil water availability expected for the next decades may turn out to be even more drastic under future warmer conditions. Nevertheless, water deficit is not the only limiting factor in arid and semiarid environments. Soils often suffer from nutrient (especially N and P) deficiencies in these ecosystems, which can also be worsened by climate change. How to improve the poor soil quality and enhance the vegetation coverage is always the problem facing ecosystem managers. The adaptive mechanisms of native plant to future climate change is always the focus in plant ecology, it also plays important roles in improving vegetation coverage by manual controlled programmes. Sophora davidii is a native perennial shrub of arid valleys, which is often predominant on eroded slopes and plays a vital role in retaining ecological stability in this region. It has been found that S. davidii was better adapted to dry environment than other shrubs, prompting its use for re-vegetation of arid lands. A two-years greenhouse experiment and a field experiment were conducted in order to understand the adaptation responses of Sophora davidii seedlings to different water and N conditions, and further explore if additional N supply as a modified role could enhance the adaptation ability of S. davidii seedlings to dry and infertile environment. Two-month old seedlings were subjected to a completely randome design with three water (80%, 40% and 20% water field capacity (FC)) and three N supply (N0: 0, Nl: 92 and Nh: 184 mg N kg-1 soil) regimes. Field experiment was arranged only by three N supplies in the dry valley. 1) The growth, biomass partitioning and water-use efficiency of Sophora davidii seedlings in respond to drought stress and N supply Seedlings height, basal diameter, leaf number, leaf area, root length, biomass production, relative water content (RWC) and WUE were decreased with increase of drought stress. An increase in below-ground biomass was observed indicating a higher root/shoot ratio (R/S) under drought stress conditions. Low N supply increased seedlings height, basal diameter, leaf number, leaf area, and biomass production, but decreased root length. In contrast, these growth characteristics showed little or negative effect to high N supply treatment. Leaf percentages increased with increase of N supply, but fine root percentages decreased. In addition, Low N supply rather than the other two N treatments increased leaf area ratio (LAR), leaf/fine root mass ratio (L/FR), R/S and RWC under severe drought stress (20%FC), even though these parameters could increase with the high N supply treatment under well-watered condition (80%FC). Moreover, Low N supply also increased WUE under three water conditions, but high N supply had little effect on WUE under drought stress conditions (40%FC and 20%FC). 2) Leaf gas exchange and fluorescence parameters of Sophora davidii seedlings in respond to drought stress and N supply Leaf area (LA), photosynthetic pigment contents, and photosynthetic efficiency were decreased with increase of drought stress, but specific leaf area (SLA) increased. Photodamage in photosystem 2 (PS2) was also observed under drought stress condition. The decreased net photosynthetic rate (PN) under relative well-watered water conditions might result from stomatal limitations, but the decreased PN under other hand, photosynthetic capacity by increasing LA, photosynthetic chlorophyll contents, Pnmax, CE, Jmax were increased with increase N supply, and photosynthetic efficiency was improved with N supply treatment under water deficit. Although N supply did a little in alleviating photodamages to PS2 caused by drought stress, low N supply enhanced qN and kept relative high Fv/Fm under drought stress condition. However, high N supply inhibited leaf photosynthetic efficiency, and declined Fv/Fm and qN under severe drought stress condition after two year continues drought stress and N supply. 3) Carbon accumulation, nitrogen and phosphorus use efficiency of Sophora davidii seedlings in respond to drought stress and N supply C, N and P accumulation, NUE , N and P uptake efficiency (NUtE and NUtE ) P N P were decreased with increase of drought stress regardless of N supply. On the other hand, the S. davidii seedlings exhibited strong responses to N supply, but the responses were inconsistent with the various N supply levels. Low N supply rather than the other two N treatments increased C, N and P accumulation, improved NUEP, NUtE and NUtE under corresponding water condition. In contrast, high N supply N P did few even depressed effects on C, N and P accumulation, and NUEP, although NUtEN and NUtEP could increase with high N supply under corresponding water conditions. Even so, a decrease of NUEN was observed with increase of N supply under corresponding water conditions. 4) Soil microbial and chemical characters in respond to drought stress and N supply The content of soil organic C, available N and P were decreased with increase of drought stress. Decreases in C/N and C/P, and invertase, urea and alkaline phosphatase activity were also observed under drought stress conditions, indicating a lower N and P mineralization rate. Although microbial biomass C, N and P showed slight responses to drought stress after one growth period treatment, microbial biomass C and N were also decreased with increase of drought stress after two year continuous treatment. The content of soil organic C and available P showed the stronger positive responses to low N supply than which to high N supply, although than the other two N treatments increased microbial biomass N and invertase activity under severe drought stress condition, even though invertase activity could increase with high N supply treatment under relative well-water conditions. Moreover, low N supply treatment also increased C/P and alkaline phosphatase activity which might result from higher P mineralization, but high N supply did negative effects on alkaline phosphatase activity. 5) The growth characteristics of Sophora davidii seedlings and soil microbial and chemical characters in respond to N supply under field condition Low N supply facilitated seedlings growth by increasing leaf number, basal diameter, root length, biomass production, C, N and P accumulation and absorption, and enhancing the use efficiency of other limited resources as P. Compared to control, however, low N supply did little effect on altering biomass, C, N and P portioning in seedlings components. On the contrary, high N supply treatment also increased leaf number, biomass and C, N and P accumulation relative to control, but significantly decreased root length, and altered more biomass and resources to above-ground, which strongly reduced the ability of absorbing water under drought condition, and thus which might deep the drought stress. In addition, N supply increased soil C, N and available N content, but declined pH and showed little effects on P content. Low N supply showed higher values of soil C and available P content. Low N supply also increased microbial biomass C, N and P, although high N supply decreased microbial biomass C. N supply significantly enhanced soil invertase, urea, alkaline and neutral phosphratase activity, while declined acid phosphratase and catalase activity. Low N supply exhibited higher alkaline and neutral phosphratase activity compared to the others. The results from this study indicated that both drought and N limited the growth of S. davidii seedlings and their biomass production. Regardless of N supply levels, drought stress dramatically reduced the seedlings growth and biomass production. Although plant growth parameters, including basal diameter, height, leaf number, and biomass and their components were observed to be positive responses to low N supply, N supply alone can not alter the diminishing tendency which is caused by drought. available N content increased with increase N supply. In addition, low N supply rather These findings imply that drought played a primary limitation role and N was only the secondary. Even so, appropriate N supply was seemed to enhance the ability that S. davidii seedlings adapted to the xeric and infertile environment by improving soil processes, stimulating plant growth, increasing recourses accumulation, enhancing use efficiency of other limited resources, and balancing biomass and resources partitioning. Appropriate N supply, therefore, would be recommended to improve S. davidii seedling establishment in this region, but excess N supply should be avoided.

鞑靼荞麦（Fagopyrum tataricum Gaertn.）离体再生与遗传转化研究

鞑靼荞麦是我国特有的农业产品，具有抗寒耐旱特性和较高的营养保健功能。荞麦的开花习性及遗传特点导致其人工杂交授粉难以成功，这成为荞麦杂交育种难以获得突破的重要原因。因此利用转基因技术导入有益基因有可能成为荞麦遗传改良的新途径，而再生及转化体系的建立是开展转基因研究的基础。 本文研究了苗龄、外植体、几种激素配比对鞑靼荞麦（Fagopyrum tataricum Gaertn.）离体培养的影响，初步建立了鞑靼荞麦离体再生体系。结果表明，鞑靼荞麦离体再生的最佳取材时间为苗龄6-8d；诱导愈伤组织的最适培养基为MS＋2.0 mg/L 2,4-D＋1.5 mg/L 6-BA，子叶诱愈率达75％左右，下胚轴的可高达86.62％；愈伤组织分化的最适培养基为MS 0.1mg/L IAA＋2.0mg/L 6-BA＋1.0 mg/L KT＋0.5mg/L TDZ，下胚轴的分化率可达9.52%。下胚轴的诱愈率与分化率均高于子叶，更适于离体再生培养。培养基中加入AgNO3后，能有效降低褐化率。生根最适培养基为含有0.5mg/L NAA的1/2MS培养基，生根率在50％左右。TDZ在诱导鞑靼荞麦的愈伤组织分化出芽的过程中起到明显的促进作用，可提高分化率约20%。 在上述研究基础上，本文还对鞑靼荞麦的遗传转化体系进行了探索性研究。分别利用根癌农杆菌（Agrobacterium tumefaciens）介导法和微粒轰击法（基因枪法）对黑水苦荞下胚轴进行遗传转化。 在农杆菌介导的方法中，携带有质粒pCAMBIA2301的农杆菌菌株EHA105用于转化。载体质粒pCAMBIA2301包含有gus和npt-II 基因, 并受35s启动子驱动。研究结果表明，在侵染方式选择上，浸泡方式比吸打方式更有效，根癌农杆菌侵染的较适浓度为OD600＝0.5，共培养3天，恢复培养7天，能检测到gus基因的表达。 基因枪法使用质粒pBI121，同样包含有gus和npt-II基因, 并受CaMV35s 启动子驱动。轰击距离为9cm较合适，甘露醇前处理在本研究中未表现出明显优势。 两种转化方法比较，基因枪法比农杆菌介导法更快速有效。 本研究为进一步的遗传操作研究打下基础。 Tartary buckwheat (Fagopyrum tataricum Gaertn.), the traditional and unique agricultural product of China, is a kind of crop with strong drought and cold tolerance, abundant nutrition and high medical value. Artificial hybridization is hard in buckwheat because of its flowering habits and genetic characteristics, which leads to no breakthrough in tartary buckwheat breeding. However, biotechnological approaches, especially genetic transformation for the direct introduction of good genes into tartary buckwheat for quality improvement, hold great promise. In this study, we established tartary buckwheat regeneration system in vitro. It is the foundation for genetic manipulation of this crop. The effects of seedling age, hypocotyl and cotyledon as explants, and proportions of several growth regulators were tested in tissue culture of tartary buckwheat for establishing its in vitro regeneration system. The results showed that the best seedling age for callus induction was 6 to 8 days. On the MS medium containing 2.0mg/L 2, 4-D and 1.5mg/L 6-BA, the induction rate of callus from hypocotyls was up to 86.62%, while from cotyledons was about 75％. The suitable shooting medium was the MS medium+0.1mg/L IAA+2.0mg/L 6-BA+1.0 mg/L KT+0.5mg/L TDZ, and the shooting rate from hypocotyls was 9.52%. The callus induction and shooting rates were higher from hypocotyls than from cotyledons. Browning reduced when the medium mixed with AgNO3. Half strength MS supplemented with 0.5mg/L NAA was the best for rooting, the rate was around 50% after 30 days culture. TDZ can accelerate the shoot differentiation distinctively, and it could improve the shooting rate nearly 20%. On the base of above, the explorative research of the genetic transformation in tartary buckwheat was done. In the study, hypocotyls from Heishui tartary buckwheat were transformed by Agrobacterium-mediated method and microprojectile bombardment method (gene-gun), comparatively. In Agrobacterium-mediated method, a disarmed Agrobacterium tumefaciens strain EHA105 harboring plasmid pCAMBIA2301 was used. The vector pCAMBIA2301 contains gus and npt-II genes, driven by CaMV35s promoter. The results showed that the appropriate concentration of Agrobacterium tumefaciens for infecting was OD600＝0.5, and co-culture time was 3d. Seven days later after coculture, GUS expression could be tested. In particle bombardment transformation, plasmid pBI121 was used. pBI121 also contains gus and npt-II genes, driven by 35s promoter. Hypocotyls pretreated with mannitol, no effect was observed, and the suitable distance of bombardment is 9cm. Comparing with Agrobacterium-mediated method, gene-gun method is more convenient and effective. All above results could be a basic work for further study in tartary buckwheat transformation.

An efficient in vitro method for mass propagation of Potentilla potaninii wolf

This study reports a method for high-frequency shoot organogenesis and plant establishment of Potentilla potaninii Wolf. Hypocotyl and cotyledon explants of P. potaninii were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of benzyladenine (BA) and alpha-naphthaleneacetic acid (NAA) to induce adventitious shoot formation for micropropagation. The highest frequency of adventitious shoot regeneration was achieved from hypocotyl and cotyledon explants grown on MS medium supplemented with 5.0 mg l(-1) BA and 1.0 mg l(-1) NAA. The regenerated shoots rooted most efficiently on half-strength MS medium supplemented with 1.0 mg l(-1) NAA and 0.5 mg l(-1) indole-3-acetic acid or indole-3-butyric acid. The acclimatized plants with normal morphology and growth characters flowered and set seeds in the following year.

Decomposition of emergent macrophyte roots and rhizomes in a northern prairie marsh

Dry mass, nitrogen and phosphorus content in belowground litter of four emergent macrophytes (Typha glauca Godr., Phragmites australis (Cav.) Trin., Scolochloa festucacea (Willd.) Link and Scirpus lacustris L.) were followed for 1.2 years in a series of experimental marshes, Delta Marsh, Manitoba. Litter bags containing roots and rhizome materials of each species were buried in unflooded soil, or soil flooded at three water depths (1–30, 31–60, > 60 cm). There were few differences in dry mass loss in unflooded or flooded soils, and depth of flooding also had little effect on decomposition rates. In the flooded sites, Scolochloa and Phragmites roots lost more mass (48.9–63.8% and 59.2–85.5%, respectively) after 112 days than Typha and Scirpus (36.3–43.6 and 37.0–47.2%, respectively). These differences continued through to the end of the study, except in the shallow sites where Scirpus roots lost more mass and had comparable mass remaining as Scolochloa and Phragmites. In the unflooded sites, there was little difference between species. All litters lost nitrogen (22.9–90.0%) and phosphorus (46.3–92.7%) during the first 112 days, then levels tended to remain constant. Decay rates for our belowground root and rhizome litters were comparable to published literature values for aboveground shoot litter of the same species, except for Phragmites roots and rhizomes which decomposed at a faster rate (−k = 0.0014−0.0032) than shoots (−k = 0.0003−0.0007, [van der Valk, A.G., Rhymer, J.M., Murkin, H.R., 1991. Flooding and the decomposition of litter of four emergent plant species in a prairie wetland. Wetlands 11, 1–16]).

vertical growth of thalassia testudinum seasonal and interannual variability

The vertical growth of shoots of the seagrass Thalassia testudinum Banks ex Konig in four meadows, along a range of exposure to waves, in the Mexican Caribbean was examined to elucidate its magnitude and its relationship to sediment dynamics. Average internodal length varied between 0.17 and 12.75 mm, and was greatest in the meadow which experienced the greatest burial by sand waves moved by Hurricane Gilbert (September 1988). Internodal length showed annual cycles, confirmed by the flower scars always preceding or coinciding with the annual minimum internodal length. These annual cycles on the shoot allowed estimation of annual leaf production, which varied, on average, between 14.2 and 19.3 leaves per shoot year-1. High vertical shoot growth was associated with long internodes and high leaf production rate, which increased with increasing vertical shoot growth to a maximum of approximately 25 leaves per shoot year-1, with vertical growth of about 30 mm year-1 or more. Average internodal length showed substantial interannual differences from perturbations derived from the passage of Hurricane Gilbert. The growth response of the plants surviving moderate burial and erosion after the hurricane involved enhanced vertical growth and increased leaf production, and reduced vertical growth, respectively, after 1988. The variability in shoot vertical growth of T testudinum can be separated into seasonal changes in plant growth, and long-term variability associated with episodic perturbations involving sediment redistribution by hurricanes.

Seed germination and seedling morphology of the seagrass, Halophila engelmannii (Hydrocharitaceae)

Seeds of Halophila engelmannii Aschers., that were collected in Redfish Bay, Texas, at weekly intervals from mid-May to mid-June 1986, began to germinate 3–4 weeks after collection. Most of the collections subsequently showed an increase in the rate of germination under increased light intensity and all had a stoppage of germination after transfer to darkness, indicating a light requirement to break endogenous seed dormancy. During the 5 weeks after seeds germinated, seedlings in soil culture produced a rosette of six leaves before the appearance of a rhizome bud in the axil of the third leaf. The first node of the rhizome produced a root and an upright shoot with a pseudowhorl of three to five leaves.

黄土丘陵区生态修复地不同抗侵蚀植物的消长变化过程

依据黄土丘陵区生态修复过程中植被演替阶段与植物生长型,将抗侵蚀植物分为一年生草本植物,多年生根茎禾草植物,多年生根蘖性草本和半灌木植物、灌木植物和乔木植物5类。一年生草本植物、多年生根茎禾草植物适应土壤侵蚀环境的能力比较强,同时具有一定程度的防止土壤侵蚀的作用;灌木和乔木植物适应土壤侵蚀环境的能力比较弱,而防止土壤侵蚀的作用很强;多年生草本和半灌木植物适应土壤侵蚀环境的能力适中,而防止土壤侵蚀作用的能力优于一年生草本和多年生根茎禾草群落,但不及乔灌木群落。并提出了在天然草本植被恢复的基础上进行人工造林的相关建议。

氮磷营养对小麦水分关系的影响

比较研究了氮磷营养对春小麦水分关系影响的差异。结果表明 ,土壤干旱情况下 ,氮磷营养虽然皆增强了春小麦的渗透调节能力 ,但由于氮磷营养对作物地上地下部生长的不同进促作用而对作物的水分状况产生了完全相反的影响。氮营养增强了作物对干旱的敏感性 ,使其水势和相对含水量大幅度下降 ,蒸腾失水减少 ,自由水含量增加而束缚水含量减少 ,并使膜稳定性降低 ;而磷营养则明显改善了植株的水分状况 ,增大了气孔导度 ,降低了其对干旱的敏感性 ,增加了束缚水含量 ,并使膜稳定性增强

原子吸收光谱法测定膜荚黄芪不同器官矿质元素含量

应用混合酸HNO3-HClO4(4∶1)在常压微沸条件下对膜荚黄芪根系及茎叶样品进行消解,采用原子吸收光谱法测定了膜荚黄芪不同器官即根及茎叶中五种人体必需矿质元素K,Fe,Zn,Mn和Cu含量,并对结果进行了统计分析与比较。该方法标准曲线相关系数为0.997 3~0.999 9,加标回收率为92.88%~109.25%,相对标准偏差(RSD,n=5)为0.393 5%~3.175 2%。方法简单,结果可靠。结果显示,膜荚黄芪根及茎叶中5种矿质元素含量顺序均为K>Fe>Zn>Mn>Cu。膜荚黄芪不同器官矿质元素含量不同,根中富含Fe,Zn,Cu元素,根内Fe含量是茎叶的1.54倍。茎叶中也含有丰富的矿质元素,特别是K和Mn元素。茎叶中K含量是根的1.63倍,这与黄芪的药效相符合。试验结果将为研究矿质元素在黄芪植株中的分布以及矿质元素含量与黄芪药效相关性提供理论依据。

土壤水分与氮肥对玉米根系生长的影响

利用田间小区试验研究了不同土壤水分条件下N肥对根系生长(根长、根重和根冠比)的影响。结果表明,玉米拔节期和开花期无论水分条件如何,施N肥可增加其总根长、表层根长和根重并使根冠比下降;灌浆期施N肥可增加总根长和表层根长,但正常水分条件下N肥使根重和根冠比下降,而干旱条件下N肥对根重和根冠比则无影响。不同处理根冠比大小与N吸收和分配有很大关系。

水肥空间组合对冬小麦生物学性状及生物量的影响

目的】研究水肥空间组合对冬小麦形态指标及生物量的影响,对指导旱地施肥具有一定理论和实践意义。【方法】以肥熟土垫旱耕人为土为供试土壤,在全生育期遮雨和人工控制土壤水分条件下,采用分层隔水土柱试验法研究与田间土层分布相同土柱不同土层水分、氮、磷组合对冬小麦叶面积、株高、分蘖数、生物量、根冠比和收获指数等指标的影响。【结果】与整体湿润水分处理相比,上干下湿水分处理(0～30cm土层干旱胁迫,30～90cm土层湿润)下,抽穗期小麦旗叶面积、株高分别降低7.03%和3.77%;小麦地上部和根系生物量及收获指数也不同程度降低,但根冠比增加。从肥料处理看,单施磷和氮磷配施处理,小麦叶面积、株高、有效分蘖数和总生物量均极显著高于单施氮和CK,这与供试土壤各土层严重缺磷,而氮素供应相对丰富有关。从不同土层施肥看,在两种水分处理下,单施氮时,以均匀施入0～90cm土层小麦叶面积、株高、有效分蘖数、地上部生物量和根系生物量最高,施入0～30cm土层最低;单施磷和氮磷配施时,0～90cm与0～30cm土层施肥间总叶面积、旗叶面积、株高、有效分蘖数以及总生物量差异不显著,但均显著高于30～60cm和60～90cm土层相应施肥处理。【...

Formation and early development of tetraspores of Polysiphonia urceolata (Rhodomelaceae, Rhodophyta)

Polysiphonia urceolata is one type of potential commercial red seaweeds used for breeding and cultivation, because of its significant biochemical and biomedical application. However, the information of breeding and seedling incubation for cultivation is limited, especially the early development. In this study, tetrasporohyte and gametophyte of P. urceolata were taken as the study materials in Huiquan Bay, Qingdao, China. The cleaned and sterilized tetrasporophytes and gametophytes were pre-cultured in sterilized seawater, then nurtured at 18A degrees C, 25 mu mol photons m(-2) s(-1) in 12:12 h (light:dark) photoperiod. Continuous observation under microscope showed that the early development consists of bipolar division stage and seedling stage. In the division stage, tetraspores germinate into bipolar sporelings that further differentiate into a colorless rhizoidal portion and a lightly pigmented upright shoot. The lightly pigmented rhizoidal cell develops to a rhizoid and the larger pigmented cell transforms to an erect axis. In the seedling stage, several quasi-protuberances appear on the erect axis and form juvenile seedlings. The results demonstrate the culture of P. urceolata from tetraspores under laboratory conditions.