金线兰种子萌发及其原球茎的增殖培养

研究了影响金线兰种子非共生萌发的因素,并应用正交试验研究基本培养基、6-BA、ZT、NAA四种因素对原球茎增殖的作用。结果表明:授粉类型对金线兰种子非共生萌发影响较大,异株异花、同株异花以及同株同花授粉所得的种子的萌发率分别为78.53%、69.62%、39.87%;蒴果成熟度以生长150d为宜,采收后萌发率可达78.59%;冷藏影响种子的活力,种子的萌发率随冷藏时间的延长而降低;使用次氯酸钠浸泡后的种子与对照相比,其萌发率无明显差异;NAA对原球茎增殖作用显著,适宜于原球茎增殖的培养基为1/2MS+ZT0.5mg/L+NAA1.0mg/L。     

溶氧、pH及其他理化因子对蓖齿眼子菜种子萌发的影响

研究了溶氧、pH、光强、冷处理、温度、营养以及激素处理等条件对蓖齿眼子菜种子萌发的影响。结果表明:溶氧对种子的最终萌发率有影响,缺氧条件下比正常条件和氧饱和条件下的萌发率高,但缺氧条件下萌发的幼苗为白化苗,不能正常生长发育;光照和pH对种子萌发的影响不显著。4℃冷处理能够使种子萌发时间提前和提高种子的萌发率;在15—27℃之间,提高温度能够加快种子的萌发速度,但温度过高则萌发率降低,在15℃、20℃和27℃下的最终萌发率分别为90.0%、90.0%和56.7%;不同的营养水平对种子萌发影响不显著。生长素NAA(0.1—5.0mg/L)、细胞分裂素6-BA(0.1—5.0mg/L)、赤霉素GA3(0.1—5.0 mg/L)不能加快蓖齿眼子菜种子萌发的速度和提高萌发率。     

白及种子萌发与快速繁殖技术的研究

将不同胚龄的白及种子接种到不同培养基中进行培养,对白及种子萌发率、萌发时间、丛生芽增殖、生根等方面进行了研究。结果表明:白及种子萌发率与其胚龄及有胚率成正相关,萌发时间则与胚龄及有胚率成负相关;胚龄16周的种子在1 g/L花宝1号 2 g/L花宝2号的培养基上萌发率可达84%;胚龄等于或大于20周的种子萌发率不受培养基成分的影响,均可达100%,萌发时间只需7 d;丛生芽增殖的最佳培养基为1/2 MS 4.0 mg/L6-BA 0.2 mg/L NAA 100 g/L CM,其增殖倍数达4.41倍;诱导生根较好的培养基为1/2 MS 0.2 mg/L NAA,生根率达90%。     

水深、基质、光和去苗对菹草石芽萌发的影响

通过野调查,研究了水深对菹草石芽萌发率的影响,比较了梁子湖与湖北省其他四个不同水深的湖泊间菹草石芽明发率月动态;并通过萌发实验探讨了基质、光和去苗对菹草石芽萌发的影响。结果如下：无光环境下菹草石芽的萌发率较有光下的小,基质的有无及其类型对萌发率影响不大,去苗能使其萌发第二苗和第三苗的百分离分别从自然状态下的3．2％和1．0％提高至96．8％和64．0％（12月初）;五个湖泊的石芽均于7月初即开始萌发,相同月份不同湖泊石芽的平均萌发率基本与其平均水深成负相关关系,但12月初各湖泊的平均萌发率相近（＞95％）;同一湖泊水深越大,相同月份的萌发率越低,水深的增加能显著推迟萌发起始时间,但不改变其最终萌发率（12月初＞95％）。菹草石高萌发率的特征和极高的萌发第二、第三苗的潜力可能是其成为许多湖泊优势种的两个极其重要的维持机制。     

胡萝卜人工种子包衣材料的筛选

以胡萝卜SK4-316种子苗下胚轴为外植体诱导培养的体细胞胚,进行人工种子的制作。结果表明,海藻酸钠包埋体系制作的人工种子萌发率较稳定,PEG体系的萌发率高于前者,但萌发后成苗率较低。以MS液体培养基作包埋培养基,4%海藻酸钠、2% CaCl₂·2H₂O、0.1 mg/L GA₃、0.2%活性炭组成的海藻酸钠复合包衣剂制作的人工种子,在1/16MS培养基、24℃下培养萌发率最高,可达97.02%。     

鹤顶兰种子萌发及原球茎增殖培养研究

以鹤顶兰成熟蒴果的种子为实验材料,研究影响种子非共生萌发的因素和种胚发育途径,并采用正交设计研究了原球茎增殖的影响因素。结果表明:冷藏影响种子的活力且其萌发率随冷藏时间延长而降低;0.5%NaClO溶液浸泡种子可提高萌发率,缩短初始萌发时间;种胚发育途径为种胚转绿后从种子侧面突破种皮而形成原球茎,随后分化出具根芽结构的完整植株;6-BA对原球茎增殖作用显著,原球茎增殖的最适培养基为1/2MS+3.0mg/L6-BA+1.0mg/L KT+1.0mg/L NAA,增殖倍数为6.67。     

富营养底质对沉水植物的胁迫研究 Ι.乙酸对伊乐藻和菹草萌发与幼芽生长的影响

湖泊底质中有机物的厌氧代谢产生多种有机酸,其中主要成分是乙酸。研究了暴露于不同浓度的乙酸溶液后伊乐藻(Elodea nuttallii)和菹草(Potamogeton crispus)无性繁殖体的萌发和幼芽的生长状况。1 mmol/L的乙酸能显著抑制伊乐藻幼芽的生长(p<0.05),但对其繁殖体的萌发无明显影响。在4 mmol/L的乙酸影响下,菹草幼芽仍有明显的生长;菹草繁殖体的萌发受到显著抑制(p<0.05),但在随后的培养中可全部萌发。4 mmol/L以上的乙酸暴露3 d或6 d导致伊乐藻全部死亡,8 mmol/L的乙酸处理6 d或16 mmol/L的乙酸处理3 d或6 d导致菹草全部死亡。研究表明厌氧底质中的乙酸可能是阻碍沉水植物生长的重要因素之一,菹草比伊乐藻能耐受较高强度的乙酸胁迫,更适合作为先锋物种用于富营养化湖泊中的沉水植物恢复。     

矮沙冬青种子特性和萌发影响因素的研究

 对矮沙冬青(Ammopiptanthus nanus)种子的特性和萌发影响因素进行了初步研究,结果表明：种子不易传播;虫蛀率高,室温贮藏60 d的种子虫害率为38%;易形成硬实,含水量为7.68%的种子在30 ℃温水中浸泡90 h,只有33.33%能吸水膨胀。种子萌发时不需光,在15～30 ℃和室温（18～32 ℃）条件下,经9 d的萌发,发芽率均可达80%以上,30℃时萌发最快;在1～2 cm深的沙壤中,种子出苗率可达75%以上,超过3 cm显著降低,超过6 cm则低于20%;种子在沙壤中萌发时,沙壤的适宜湿度为19.35%～28.75%,高于32.43%或低于3.85%,很少有种子萌发;含水量分别为19.36%、10.64% 和7.68%的种子发芽率无显著差异,在-10 ℃和5 ℃下贮藏7个月,发芽率也无显著降低,但在室温和35 ℃下贮藏7个月则显著下降,发芽率下降的速度与种子本身的含水量和贮藏温度正相关;在湿度分别为7.41%、13.79%和28.57%的沙壤中播种育苗,幼苗死亡率高达77.49%、81.25%和89.49%,即使用三唑酮拌种,死亡率亦高达50.27%、69.53%和76.03%,幼苗死亡率与沙壤湿度正相关。     

富营养底质对沉水植物的胁迫研究 Ι.乙酸对伊乐藻和菹草萌发与幼芽生长的影响

湖泊底质中有机物的厌氧代谢产生多种有机酸,其中主要成分是乙酸。研究了暴露于不同浓度的乙酸溶液后伊乐藻(Elodea nuttallii)和菹草(Potam ogeton crispus)无性繁殖体的萌发和幼芽的生长状况。1 mmol/L的乙酸能显著抑制伊乐藻幼芽的生长(p<0.05),但对其繁殖体的萌发无明显影响。在4 mmol/L的乙酸影响下,菹草幼芽仍有明显的生长;菹草繁殖体的萌发受到显著抑制(p<0.05),但在随后的培养中可全部萌发。4 mmol/L以上的乙酸暴露3 d或6 d导致伊乐藻全部死亡,8 mmol/L的乙酸处理6 d或16 mmol/L的乙酸处理3 d或6 d导致菹草全部死亡。研究表明厌氧底质中的乙酸可能是阻碍沉水植物生长的重要因素之一,菹草比伊乐藻能耐受较高强度的乙酸胁迫,更适合作为先锋物种用于富营养化湖泊中的沉水植物恢复。     

青霉素对老化香瓜种子萌发和酶活性的影响

以人工老化的香瓜种子为材料,用浸种预处理的方法,研究不同浓度青霉素对老化香瓜种子萌发及酶活性的生理生化效应,摸索了种子吸涨时间,萌发时间,萌发率,可溶性糖,可溶性蛋白含量及POD和SOD活性随青霉素浓度变化的特点和规律,结果表明：200～300mg/L青霉素可显著促进种子吸胀,缩短萌发时间：300～400mg/L青霉素处理可显著提高发芽率,发芽率和发芽指数的提高均达到极显著水平;300mg/L浓度对膜系统的稳定性最强,300～400mg/L浓度范围内,SOD,POD活性最高,故300mg/L青霉素是促进老化香瓜种子萌发和幼苗生长的最佳处理浓度。     

Wave exposure related growth of epiphyton: implications for the distribution of submerged macrophytes in eutrophic lakes

The distribution of submerged macrophytes in eutrophic lakes has been found to be skewed towards sites with intermediate exposure to waves. Low submerged macrophyte biomass at exposed sites has been explained by, for instance, physical damage from waves. The aim of this study was to investigate if lower biomass at sheltered sites compared to sites with intermediate exposure to waves can be caused by competition from epiphyton.Investigations were performed in eutrophic lakes in southern Sweden. Samples of submerged macrophytes and epiphytic algae on the macrophytes were taken along a wave exposure gradient. The amount of epiphyton (AFDW) per macrophyte biomass decreased with increased exposure. Biomass of submerged macrophytes, on the other hand, increased with increased exposure until a relatively abrupt disappearance of submerged vegetation occurred at high exposures. Production of epiphytic algae was monitored on artificial substrates from June to September at a sheltered and an exposed site in three lakes. It was higher at sheltered sites compared with exposed sites.We suggest that epiphytic algae may be an important factor in limiting the distribution of submerged macrophytes at sheltered sites in eutrophic lakes.     

Germination Requirement of Vallisneria natans Seeds: Implications for Restoration in Chinese Lakes

Due to eutrophication submerged macrophytes have disappeared from many Chinese lakes. This is unfortunate as submerged macrophytes are important to improve water quality, and its re-establishment is therefore desirable. For this purpose a potential method to use is re-seeding, this being particularly attractive due to the high seed productivity of V. natans. We conducted laboratory studies to investigate the effects of five environmental variables (temperature, substratum, oxygen, light availability, and burial depth) on the seed germination of V. natans. Our results showed that a wide temperature range (25–35 °C) was favorable for germination; that seeds germinated well under both gravel and silt; that anaerobic condition proved to accelerate seed germination although the final germination percentage did not rise; and that light and burial acted as limiting factors. These results suggest that V. natans is a potential candidate for successful restoration of vegetation in lakes recovering from eutrophication.     

沉水植物重建对富营养水体氮磷营养水平的影响

利用富营养浅水湖泊(武汉东湖)中所建立的大型实验围隔系统,研究了沉水植物对水体N、P营养水平的影响．结果表明,沉水植物重建后N、P营养水平显著降低．在研究期间,水生植物围隔总N和总P水平均显著低于对照围隔和大湖水体,而且水生植物围隔的总P含量一般维持在0．1mg·L^-1左右。季节性波动远低于对照围隔和大湖水体．水生植物围隔水体中氨态氮和亚硝态氮含量较低．而硝态氮含量与对照围隔和和大湖水体差别不大．由此可见。恢复以沉水植物为主的水生植被,可以有效地降低N、P营养循环速度,控制浮游植物过度增长,是重建富营养湖泊生态系统的重要措施．     

梁子湖优势沉水植物冬季种子库的初步研究

初步研究了梁子湖6种优势沉水植物如黄丝草、金鱼藻、菹草、黑藻、苦草和穗状狐尾藻等在冬季的广义种子库（种子、芽苞、断枝等）,包括它们的繁殖特性、种子在小、结构及萌发时的衰减曲线等问题,主要结果为：（1）在梁子湖不同区域内,种子库大小不相同,满江湖、前江大湖、中湖和管理局网围内种子库分别为714.4粒／m^2、107.5粒／m^2、331.9粒／m^2和159.3粒／m^2。种子库的大小受到现实的种群数量、投鱼强度、人类干扰等因素的影响。（2）黄丝草、金鱼藻、菹草种九的种子库占有明显优势,全湖平均分别为198.8粒／m^2、91.7粒／m^2和21.4粒／m^2。（3）每一种植物种群广义种子库的构成和比例具有差异,金鱼藻、菹草、苦草、黑藻四种植物种子库中,无性繁殖体占有主要的地位;黄丝草、穗状狐尾藻两种植物种子库中,种子占有很大的比例,上述六种植物均可用种子和无性繁殖体来产生幼苗,补充到肿群中去。（4）种子库一般存在冬季休眠（菹草为夏眠）,春季种子库萌发,尤其在3月和4月是种子库萌发的高峰期。     

Phytoplankton biomass in Lake Xolotlán (Managua): Its seasonal and horizontal distribution

Some well-documented studies on restoring eutrophic lake systems in The Netherlands by fish stock management have been evaluated with the emphasis on the role of macrophytes. Furthermore, the factors determining the light climate for submerged macrophytes in a large shallow eutrophic lake (Lake Veluwe) have been assessed and the potential success of biomanipulation in large scale projects is discussed. Today relatively little attention has been paid to macrophyte management although the importance of macrophytes in lake restoration has been recognized regularly. The biomanipulation strategy was successful in small scale projects. In a large scale project, however, wind-induced resuspension may largely determine the underwater light climate through attenuation by the water column and periphytic layer. Therefore, restoration of relatively large waterbodies by fish stock management only is expected not to lead to any noteworthy improvement of the light climate for submerged macrophytes. Additional measures aimed at reducing wind-induced resuspension of sediment particles and reestablishing of the macrophyte stands are required for successful biomanipulation strategies. Water quality managers should pay more attention to macrophyte stands in biomanipulation projects because macrophytes enhance a more stable and diverse ecosystem. Restoration objectives and the methods of their achievement must be carefully planned since an abundant submerged macrophyte vegetation may have undesirable effects as well.     

Restoring macrophyte diversity in shallow temperate lakes: biotic versus abiotic constraints

Although many lake restoration projects have led to decreased nutrient loads and increased water transparency, the establishment or expansion of macrophytes does not immediately follow the improved abiotic conditions and it is often unclear whether vegetation with high macrophyte diversity will return. We provide an overview of the potential bottlenecks for restoration of submerged macrophyte vegetation with a high biodiversity and focus on the biotic factors, including the availability of propagules, herbivory, plant competition and the role of remnant populations. We found that the potential for restoration in many lakes is large when clear water conditions are met, even though the macrophyte community composition of the early 1900s, the start of human-induced large-scale eutrophication in Northwestern Europe, could not be restored. However, emerging charophytes and species rich vegetation are often lost due to competition with eutrophic species. Disturbances such as herbivory can limit dominance by eutrophic species and improve macrophyte diversity. We conclude that it is imperative to study the role of propagule availability more closely as well as the biotic interactions including herbivory and plant competition. After abiotic conditions are met, these will further determine macrophyte diversity and define what exactly can be restored and what not.     

Influence of submerged vegetation and fish abundance on water clarity in peri-urban eutrophic ponds

Despite the presence of high nutrient concentrations, most ponds located around Brussels (Belgium) show a considerable variation in turbidity. The importance of submerged macrophytes in maintaining the clear-water state requires identification of the main factors determining macrophyte abundance and diversity in ponds and small lakes. In this study, the inter-relationships between submerged macrophyte cover, fish abundance and turbidity were investigated in 13 eutrophic peri-urban ponds. Along a turbidity gradient, vegetation switched from dominance by Stoneworts (Chara and Nitella spp.) in the clearest ponds, to dominance by Potamogeton pectinatus in ponds with a slightly lower water transparency. Despite the presence of both P. pectinatus and Stoneworts in each of the vegetated ponds, only one became dominant. Only a very low abundance (around 20%) of submerged vegetation was found in ponds of intermediate turbidity, while macrophytes were absent in turbid ponds. Multi- and univariate analysis showed a marked difference in chemical, physical and biological properties between ponds deliberately used for fish stocking and ponds that were not. Macrophyte cover was significantly negatively correlated with turbidity and plankti-benthivorous fish abundance. No such correlation was observed with piscivorous fish abundance, except for pike that were associated with a charophyte vegetation in the study ponds. The strong relationship found between fish abundance and turbidity, its negative effect on submerged vegetation cover, and the importance of submerged vegetation in controlling phytoplankton abundance, should be taken into account when selecting ponds for fish stocking. It also suggests that the study ponds have a good potential for ecological quality restoration by biomanipulation.     

Chironomid stratigraphy in the shallow and eutrophic Lake Søbygaard, Denmark: chironomid–macrophyte co-occurrence

1. A sediment core from the shallow, hypertrophic Lake Søbygaard (mean depth ∼1 m; [TP] 310 μg P L⁻¹) was analysed for subfossil remains to reconstruct chironomid community changes in relation to the succession and disappearance of aquatic macrophytes. 2. Species composition in the 1.10 m core indicates a succession from a 'naturally' eutrophic state to a hypertrophic state during recent centuries. Radiometric dating (²¹⁰Pb) of the uppermost 20 cm of the sediment core (∼1932–93) indicates that sediment accumulation rate had doubled in recent decades. 3. Changes in chironomid assemblages were in close agreement with changes in both diatoms and macrophyte remains in the same core. Distinct changes in chironomid communities reflect the eutrophication process and macrophyte succession through Chara , Ceratophyllum and Potamogeton dominance to the present state, with complete loss of submerged vegetation and dominance by phytoplankton. 4. The co-occurrence and relationship between aquatic macrophyte diversity and recent subfossil chironomid assemblages were assessed from an additional 25 Danish lakes. There was good agreement between the macrophyte and chironomid-based lake groupings. Overall, a significant difference ( P <0.001) was found in chironomid assemblages among lakes in different macrophyte classes. In a pair-wise comparison, the poorly buffered mesotrophic lakes and the alkaline eutrophic lakes had significantly different chironomid assemblages. 5. Chironomid taxa commonly reported to be associated with macrophytes ( Cricotopus , Endochironomus and Glyptotendipes ) were shown also to be indicators of highly productive lakes lacking abundant submerged vegetation.     

黄河三角洲菹草生长模型及其对水质的影响

通过连续对菹草生长过程的观测 ,用指数方程拟合了菹草从 10月中旬至第 2年 5月底的整个生长过程 (p<0 .0 0 2 ) ,设K=2 .5 kg/ m2时 ,用 L ogistic方程拟合了从 3月到 5月底的生长过程 (p<0 .0 0 0 )。通过 7月底至 8月初、10月、翌年 3月和 5月份对一个菹草型水库和无或有不同规模水草的 5座水库水生生物的周年调查发现 :(1)菹草型水库 TP最高峰的月份比其它水库的推迟 ,其它水库 10月份 TP最高 ,而菹草型水库 3月份最高 ;(2 )菹草型水库浮游植物最高峰的月份比无水草水库的推迟 ,无水草水库出现在夏季 (7～ 8月份 ) ,草型水库的出现在秋季 (10月份 ) ;(3)菹草型水库 3月份浮游植物生物量明显高于其它水库的 ,其硅藻占据更高的优势度 ;(4 )菹草型水库和其它水库之间的总磷和浮游植物数量的年平均值无明显差别 ;(5 )不同水库藻类数量年平均值与 TP年平均值相关极显著 (p<0 .0 0 5 ) ,而 TP又与氯化物 (Cl)相关极显著 (p<0 .0 0 5 ) ;(6 )水草的存在使p H略有提高 ,并使其在不同时间的波动幅度减小     

Invasive Crayfish Threaten the Development of Submerged Macrophytes in Lake Restoration

Submerged macrophytes enhance water transparency and aquatic biodiversity in shallow water ecosystems. Therefore, the return of submerged macrophytes is the target of many lake restoration projects. However, at present, north-western European aquatic ecosystems are increasingly invaded by omnivorous exotic crayfish. We hypothesize that invasive crayfish pose a novel constraint on the regeneration of submerged macrophytes in restored lakes and may jeopardize restoration efforts. We experimentally investigated whether the invasive crayfish (Procambarus clarkii Girard) affects submerged macrophyte development in a Dutch peat lake where these crayfish are expanding rapidly. Seemingly favourable abiotic conditions for macrophyte growth existed in two 0.5 ha lake enclosures, which provided shelter and reduced turbidity, and in one lake enclosure iron was added to reduce internal nutrient loading, but macrophytes did not emerge. We transplanted three submerged macrophyte species in a full factorial exclosure experiment, where we separated the effect of crayfish from large vertebrates using different mesh sizes combined with a caging treatment stocked with crayfish only. The three transplanted macrophytes grew rapidly when protected from grazing in both lake enclosures, demonstrating that abiotic conditions for growth were suitable. Crayfish strongly reduced biomass and survival of all three macrophyte species while waterfowl and fish had no additive effects. Gut contents showed that crayfish were mostly carnivorous, but also consumed macrophytes. We show that P. clarkii strongly inhibit macrophyte development once favourable abiotic conditions for macrophyte growth are restored. Therefore, expansion of invasive crayfish poses a novel threat to the restoration of shallow water bodies in north-western Europe. Prevention of introduction and spread of crayfish is urgent, as management of invasive crayfish populations is very difficult.