Acid phosphatase activity in intercellular spaces in roots of Nymphoides peltata (S. G. Gmel.) O. Kuntze

Abstract. Acid phosphatase was found cytochemically in intercellular spaces in the root of Nymphoides peltata. Different methods, using lead salts and azo-dyes, gave similar results. Reaction product appeared on material, possibly cytoplasmic, within the intercellular spaces and also against the outer walls of cells which formed the intercellular spaces. Possible functions of acid phosphatase in intercellular spaces are discussed.     

Sites of acid phosphatase in the differentiating root protophloem of Nymphoides peltata (S.G. Gmel.) O. Kuntze.

Abstract Sites of acid-phosphatase activity were found in the differentiating root protophloem of Nymphoides peltata by lead-salt and by azo-dye methods. Different substrates revealed different subcellular locations of the enzyme. The substrates β-glycerophosphate (β-GP) and naphthol ASBI phosphate revealed enzyme activity at similar sites within the sieve element. These sites included plasmodesmata, dictyosomes and small vacuoles in the cytoplasm. The substrate p-nitrophenylphosphate (p-NPP), however, revealed additional sites of acid-phosphatase activity which were not detectable by either naphthol ASBI phosphate or β-GP. For example, the inner region of the wall in mature sieve elements showed conspicuous acid-phosphatase activity only when p-NPP was used as substrate. The significance of the different locations of acid phosphatase within the sieve element is discussed. The convoluted ER, characteristic of immature sieve elements of N. peltata, failed to show acid-phosphatase activity whichever substate was used. By contrast, the stacked ER found in the parietal layer of mature sieve elements showed prominent acid-phosphatase activity regardless of the substrate used. The demonstration of acid-phosphatase activity in the stacked ER, and by both lead-salt and azo-dye methods, suggests that this organelle is a true site of acid-phosphatase activity. The onset of acid-phosphatase activity in the ER in later stages of sieve-element differentiation is compatible with the view that stacked ER plays a role in the final autolysis of the sieve-element protoplast.     

The Effects of Competition on Growth and Biomass Allocation in Nymphoides peltata (Gmel.) O. Kuntze Growing in Microcosm

Two experiments were designed to investigate the effects of competition on growth and biomass allocation in Nymphoides peltata. First, competition between N. peltata and Zizania latifolia was assigned with the densities of N. peltata to Z. latifolia ratios of 4:0, 4:2, 4:4 and 4:8. The increase of density of Z. latifolia resulted in apparent decrease of total biomass, relative growth rate (RGR), leaf area ratio (LAR) and mean leaf area per plant of N. peltata. N. peltata allocated above-ground biomass to shoots and roots and decreased the ratios of above-ground to below-ground biomass (A _b/B _b) with increasing density of Z. latifolia. Second, competitions between N. peltata and emerged Z. latifolia, floating-leavedTrapa bispinosa and submerged Myriophyllum spicatum were studied in the mean time. Total biomass, A _b/B _b and mean leaf area per plant of N. peltata were higher when competing with floating-leaved T. bispinosa than in N. peltata growing in the community with submerged M. spicatum and emerged Z. latifolia. There were no significant differences in RGR, net assimilation rate (NAR) and LAR of N. peltata when growing with each of the competitor species. Our studies indicate that the growth of N. peltata is strongly inhibited by the presence of Z. latifolia, and N. peltata can show certain competitive advantages over T. bispinosa and M. spicatum.     

Calcium-Dependent Lamina Production of Nymphoides peltata (Gmel.) O. Kuntze (Menyanthaceae): Implications for Distribution

Nymphoides peltata (Gmel.) O. Kuntze, a nymphaeid macrophyte,occurs commonly in polder and fluviatile areas in large partsof Europe and Asia. In contrast to the nymphaeid macrophytesNymphaea alba L. and Nuphar lutea (L.) Sm., Nymphoides peltatais almost completely absent from poorly-buffered waters andis never found in acid water bodies. Transplantation experimentsin water bodies of varying alkalinity demonstrated that, irrespectiveof the sediment type, leaf production of Nymphoides did occurin poorly-buffered waters, but not in acid waters. Cultivation experiments showed that floating leaf developmentof Nymphoides peltata could only take place if sufficient calciumwas available in the water layer or in twice-demineralized water.Addition of calcium to an acid cultivation medium or to watercollected from an acid moorland pool resulted in leaf production.Growth of Nymphoides in acid waters is impossible due to insufficientcalcium concentrations in the water layer of such waters. Itis suggested that the absence of Nymphoides peltata in somepoorly-buffered water bodies is partly due to the spatial isolationfrom rivers and canals and the high frequence of desiccation.The restricted occurrence of Nymphoides peltata to well-bufferedalkaline waters is functionally more related to the calciumavailability than to the bicarbonate content. Key words: Aquatic macrophytes, distribution, Nymphoides peltata, leaf production, calcium, acid, poorly-buffered and alkaline water     

Competitive Performance of Nymphoides Peltata (Gmel.) O. Kuntze Growing in Microcosm

Two experiments were conducted to investigate the effects of competition on growth and performance of Nymphoides peltata (Gmel.) O. Kuntze in microcosm. Part of the research on growth and biomass allocation of N. peltata in response to competition had been reported early (Wu, Z. & D. Yu, 2004, Hydrobiologia 527: 241–250). This paper focuses on the morphological variations of N. peltata under competitive pressure. First, competition between N. peltata and Zizania latifolia (Griseb.) Turcz. ex Stapf. was assigned with the densities of N. peltata to Z. latifolia ratios of 4:0, 4:2, 4:4 and 4:8. Water surface coverage, surface area per leaf blade and number of leaves per plant of N. peltata all declined significantly with increasing density of competitor. Similar results were also found for petiole length and density of branching. However, the variations of planting density did not significantly affect the number of ramets per plant and the stolon length of N. peltata. Second, competitions between N. peltata and emerged Z. latifolia, floating-leaved Trapa bispinosa Roxb. and submerged Myriophyllum spicatum L. were also studied simultaneously. The results showed that significant difference was only found for the water surface coverage of N. peltata. No other significant differences were found for the number of ramets per plant, number of leaves per plant, density of branching, surface area per leaf blade, petiole length, and stolon length of N. peltata. Our studies indicate that N. peltata presents morphological variations when it is growing with Z. latifolia, such that the growth of above-ground parts decrease (i.e., leaf number, petiole length, branching density) and the growth of below-ground parts remains stable (i.e., stolons length). However, N. peltata does not show apparent differences in morphology when it is growing with T. bispinosa or M. spicatum. Accordingly, we conclude that the growth of N. peltata may be apparently inhibited by the presence of Z. latifolia, while T. bispinosa and M. spicatum may have little impact on the growth and performance of N. peltata.     

Germination requirements and seed banks of some nymphaeid macrophytes: Nymphaea alba L., Nuphar lutea (L.) Sm. and Nymphoides peltata (Gmel.) O. Kuntze

SUMMARY.

• 1 Germination experiments demonstrated that the innate dormancy of the seeds of Nymphaea alba L., Nuphar lutea (L.) Sm. and Nymphoides peltata (Gmel.) O. Kuntze could be overcome by a cold treatment. Light stimulated the germination of the three species. Hypoxic conditions stimulated the germination of Nymphaea alba and Nuphar lutea seeds but the seeds of Nymphoides peltata did not germinate under these conditions.
• 2 Experimental seed banks of Nymphaea alba, Nuphar lutea and Nymphoides peltata were laid out in three water bodies, varying in pH and alkalinity. Germination patterns indicated that Nymphaea alba and Nuphar lutea produce transient seed banks, but that Nymphoides peliata produces a persistent seed bank. Sampling of natural seed banks and subsequent germination tests were in concordance with the results of the seed bank experiment.
• 3 The experimental above-ground seed banks of Nymphaea alba, Nuphar lutea and Nymphoides peltata showed similar germination patterns in the three selected water bodies, despite the differences in pH and alkalinity between them. However, the distribution of Nymphoides peliata is restricted to well-buffered waters, so that its absence from soft and acid water bodies must be due to post-germination mechanisms and/or processes.
• 4 In aquatic systems where Nymphoides peltata co-exists with the other nymphaeid species studied, it is largely restricted to a bell between the helophytes and the vegetation at deeper sites. The deeper sites were dominated by Nuphar lutea and Nymphaea alba. Germination requirements and seedling emergence from buried seeds of Nymphaea alba, Nuphar lutea and Nymphoides peliata play an important role in the establishment of the zonation pattern of these nymphaeid macrophytes.

     

Nymphoides peltata (Gmel.) Kuntze, Myriophyllum spicatum L. and Ceratophyllum demersum L. biomass dynamics in Lake Provala (the Vojvodina Province, Serbia)

Sixty-five plant species have been found in Lake Provala (the Vojvodina Province, Serbia) and its riparian zone. Among them, three hydrophytes were dominant: Nymphoides peltata, Myriophyllum spicatum and Ceratophyllum demersum. As interactions between different ecological factors, especially light, temperature and nutrient level, are of prime importance for productivity of macrophytes, we analyzed the main physical and chemical indicators of water quality in the studied location. In the vegetation period of the year 2000, the dominant hydrophytes were analyzed for biomass production dynamics in the studied aquatic ecosystem, including fresh weight (FW), dry weight (DW) and ash free dry weight (AFDW). The studied plant species achieved maximum biomass production in June, with statistical differences among the species at the significance level of α = 0.05.     

Initial decomposition ofNymphoides peltata (Gmel.) O. Kuntze (Menyanthaceae), as studied by the leaf-marking method

Summary In this paper the leaf-marking method as used for the study of the development and initial decomposition of floating leaves is described and the reliability of the various measurements is tested and/or discussed. Some general results obtained withNymphoides peltata (Gmel.) O. Kuntze in tanks and in the field are presented and crltically discussed. Autolysis followed by microbial decay was in all cases the most important factor by which leaves disintegrated. In the field plots animals were responsible for the disappearance of 22% of the total leaf area produced during a growth season. This is, however, the combined effect of consumption and damage succeeded by microbial decay. Real grazing can be estimated to be no more than 10% of the production of floating leaves. Fungi can have an important role in initial decomposition, especially after the flowering period, as is demonstrated forSeptoria villarsiae Desm. All damage types show temporal and, in the case of animals, also spatial distribution patterns.     

In situ studies on the breakdown ofNymphoides peltata (Gmel.) O. Kuntze (Menyanthaceae); Some methodological aspects of the litter bag technique

Summary Thein situ breakdown ofNymphoides peltata (Gmel.) O. Kuntze has been studied with special attention for methodology by: (1) using fresh and pre-dried material to establish the influence of pre-drying on breakdown and losses of nutrient stocks during decomposition; (2) enclosing different amounts of material in litter bags; (3) using litter bags with different mesh sizes, and (4) placing litter bags in water (floating leaves, petioles), on the sediment (long shoots) and in the hydrosoil (short shoots, roots). Of the material incubated in water, the floating leaves decomposed at a faster rate than the petioles, while the long shoots had the slowest breakdown. In the sediment the short shoots disappeared at a faster rate than the roots. By incubating the same morphological structure, both in the water and the sediment it appeared that the rate of breakdown was faster in the upper layers of the sediment. Pre-dried plant parts showed in water a larger initial weight loss than normal senescent plant parts, while in the sediment dried plant parts had a significantly slower loss of mass than the freshly incubated structures. Losses of nutrient stocks during decomposition were also markedly altered by pre-drying the material. When a larger amount ofNymphoides material was enclosed in the bags a tendency of a faster decay could be demonstrated. Macro-invertebrates colonized the litter bags with the 0.5 mm mesh size but usually could not-enter the 0.25 mm mesh size bags. The browsing of the detritivores did not result in a faster disappearance of organic matter, but organic matter must have been transported into the bags resulting in a larger amount of remaining organic matter when compared with the 0.25 mm mesh size bags.     

外源多胺对铜胁迫下荇菜叶片生物膜的保护作用

研究外源亚精胺和精胺对铜胁迫下荇菜叶片细胞膜透性、膜脂脂肪酸组成、光合、呼吸、铜积累影响的结果表明,50μmol·L^-1CuSO4处理导致膜脂脂肪酸组分中饱和脂肪酸组分增加,不饱和脂肪酸组分及不饱和指数（IUFA）下降,细胞膜透性加大,光合速率下降,呼吸速率迅速上升,铜在叶细胞中大量积累。外施0．1mmol·L^-1亚精胺和精胺可以稳定生物膜的结构和功能,降低铜在细胞中的累积。     

Hg^2＋对金银莲花根和叶片的伤害

研究了汞离子胁迫下金银莲花〔Ｎｙｍｐｈｏｉｄｅｓｉｎｄｉｃａ（Ｌ．）Ｋｕｎｔｚｅ〕根受害情况、根部过氧化物酶活性和新叶叶绿素含量的变化。根部受害程度随汞离子浓度升高和处理时间的延长而加重。低浓度Ｈｇ２＋短时间处理后根过氧化物酶活性升高,而高浓度Ｈｇ２＋长时间处理后根过氧化物酶活性下降,且随着Ｈｇ２＋浓度的升高或处理时间的延长过氧化物酶活性均呈下降趋势。新叶叶绿素含量对Ｈｇ２＋胁迫的反应与根过氧化物酶活性的变化相似。     

Structure and annual biomass production of Nymphoides peltata (Gmel.) O. Kuntze (Menyanthaceae)

In 1980, the monthly changes in biomass and plant surface area, together with aspects of production of Nymphoides peltata (Gmel.) O. Kuntze were studied in a backwater of the river Waal (The Netherlands). Furthermore, the seasonal changes in the vertical stratification of the biomass were studied in concrete tanks. These seasonal changes were studied with the harvest method, while the estimation of the net primary production was based upon biomass data and turnover rates of various plant parts. The data thus obtained are compared with those of other water plants, especially other floating-leaved macrophytes. In 1980, N. peltata reached its peak biomass in August being 372 g AFDW m⁻² (ash-free dry weight). The annual net productivity of Nymphoides was estimated to be 1036 g AFDW m⁻². The leaf blades and their petioles contributed most to the production.     

Nitrogen and phosphorus accumulation and cycling by Nymphoides peltata (Gmel.) O. Kuntze (Menyanthaceae)

In 1980, the seasonal changes in nitrogen and phosphorus concentration of various plant parts of Nymphoides peltata (Gmel.) O. Kuntze, together with aspects of nitrogen and phosphorus cycling by this species were studied in an oxbow lake of the river Waal (The Netherlands). The nitrogen and phosphorus stores of the water, seston, sediment and macrophyte compartments were assessed each month.The underground Nymphoides structures had high nitrogen and phosphorus concentrations before and after the main growing season, while during summer the aboveground plant parts had high nutrient contents. Nymphoides peltata accumulated maximum amounts of nitrogen (334 mmol m⁻²) and phosphorus (56.6 mmol m⁻²) in July. The upper layers of the bottom appeared to be an enormous nutrient reservoir (94–99% of total) of which the largest part was not directly available to Nymphoides. Nutrient uptake from the sediments by N. peltata is suggested by the fact that the bottom and/or interstitial water of the sample station devoid of rooted macrophytes, contained higher concentrations of nitrogen and phosphorus than that of the Nymphoides stands. The annual flux of nutrients from Nymphoides to the detritus compartment was estimated to be ca. 1200 mmol nitrogen and 164 mmol phosphorus per m² of littoral. During breakdown of the detritus there was a relatively fast net conversion of organically bound nitrogen and phosphorus to inorganic forms, especially at higher temperatures.Nymphoides has the potential to function as an important nitrogen and phosphorus pump, which regenerates sediment nutrients.     

Weather and herbivores influence fertility in the endangered fern Botrychium multifidum (S.G. Gmel.) Rupr

Fluctuations in local weather conditions and other stochastic processes are important factors affecting species population persistence. We studied two differently sized populations of the rare and declining fern species Botrychium multifidum for 4 and 5 years, respectively. Individually marked plants in permanent plots were followed to detect trends in population size, reproductive success and dormancy in relation to local precipitation and temperature. Our applied logistic regression model suggests that the shortage of precipitation during summer decreases fertility in the next year in both populations. Invertebrate herbivory of the fertile part of the plant additionally diminishes the output of spores. We found the population size to be stable with a very low percentage of each population composed of juvenile plants. Stochastic processes and low recruitment could easily lead to the extinction of these populations.     

Boron re-translocation in tea (Camellia sinensis (L.) O. Kuntze) plants

Boron (B) re-translocation is an important factor determining tolerance to B deficiency in plants. In this work growth, B content of leaves with different ages, B partitioning between soluble and cell wall (CW) fractions, and B re-translocation were investigated in tea (Camellia sinensis (L.) O. Kuntze) plants grown hydroponically without (<2.5 μM) and with adequate (46 μM) B supply. Under B deficiency, the proportion of CW bound B increased in the old leaves but decreased in roots. Contrastingly, the proportion of CW bound B was not influenced by B supply in the young leaves. A continuous reduction of B content was observed in all fully expanded leaves as well as in roots of low B plants. Taken together, these results revealed considerable re-translocation of B from mature to growing leaves. Leaf extract and phloem exudate samples were analyzed and sucrose, glucose, and fructose were detected while xylitol, sorbitol, mannitol, maltose, galactose, cellobiose or rafinose were not found in these samples. In the leaf extracts, concentration of sucrose increased under B deficiency conditions, concentration of glucose decreased, while that of fructose remained unchanged. Our results provide circumstantial evidence for a considerable re-translocation of B in tea plants despite lacking polyol compounds.     

Reproductive success and genetic structure of populations of the heterostylous aquatic plant Nymphoides indica (L.) Kuntze (Menyanthaceae)

Differences in the reproductive mode (sexual and vegetative reproduction) between populations of a species may produce diverse patterns of genetic structure within and among populations. We analyzed the clonal diversity of populations of a heterostylous plant (Nymphoides indica (L.) Kuntze) having different floral morph ratios in the Higashi-harima area of Japan. The number of MLGs (multilocus genotypes) in populations with equal floral morph ratios was significantly higher than that among populations with biased floral morph ratios and among monomorphic populations. Populations with equal floral morph ratios followed the Hardy–Weinberg equilibrium. A dispersal distance of 0–4.2 km was significantly correlated with Nei's genetic distance, supporting a stepping-stone model of dispersal. Four rare MLGs were included in populations with equal floral morph ratios, distributed among neighboring populations. We concluded that clonal diversity of N. indica in the Higashi-harima area is maintained by the success of seed production and establishment of seedlings, and by the proximate occurrence of habitats around the populations where successful sexual reproduction occurs.     

The effect of water-level fluctuations on seedling recruitment in an aquatic macrophyte Nymphoides indica (L.) Kuntze (Menyanthaceae)

We examined seed bank characteristics and seed germination and the survival of seedlings to understand the significance of water-level fluctuations on sexual regeneration in Nymphoides indica (L.) Kuntze. The seed bank existed throughout the pond. The longevity of the seed bank was more than 3 years. Seed germination started on the exposed mudflat as soon as water drawdown occurred. At the juvenile stage, exposed conditions were required for seedling growth and the young seedlings died under submergence. It was suggested that seedling establishment was successful after occasional water drawdown or along the water margin according to the period and pattern of water-level fluctuation. This study indicated the significance of the exposed mudflat at the water edge for seed germination and the growth of juvenile plants to the success of sexual regeneration in N. indica.     

Conservation of the Lake Kasumigaura population of Nymphoides indica (L.) Kuntze based on genetic evaluation using microsatellite markers

We compared the genetic diversity of the Lake Kasumigaura population of Nymphoides indica with that of pond populations in Hyogo and Kagawa Prefectures, which are thought to maintain high genetic diversity, to elucidate the current genetic diversity and occurrence of distinctive alleles in the Lake Kasumigaura population. The genetic diversity, as measured by the mean number of alleles per polymorphic locus, effective number of alleles per locus, mean observed heterozygosity, mean expected heterozygosities, total gene diversity, and number of multilocus genotypes was lower in the Lake Kasumigaura population than in the Hyogo and Kagawa populations. In addition, the inbreeding coefficient suggests that random mating does not occur in the Lake Kasumigaura population. The degree of genetic differentiation between the Lake Kasumigaura population and the Hyogo and Kagawa populations suggests that the Lake Kasumigaura population is largely genetically distinct. We found five genotypes in the Lake Kasumigaura population that were absent from the Hyogo and Kagawa populations. These results demonstrate that the Lake Kasumigaura population is an important component of the overall genetic diversity of N. indica in Japan.     

Study of submerged aquatic vascular plants in Northern Glacial Lakes (New York State,U.S.A.)

The submerged aquatic vascular vegetation was studied in the Finger Lakes and in two bays of Lake Ontario in northern New York State, U.S.A. The species composition, structure and biomass of the communities are related to the principal habitat factors such as trophic status of the lakes, bottom slope and substrate, current and stream effects, and depth. A record of the development of changes in the trophic status of the lakes and in the species composition of their submerged vascular vegetation is outlined. An attempt is made to assess the effects of catastrophic events (floods and cloudbursts in the watershed) on the lake vegetation.     

椭圆萝卜螺Radix swinhoei (H. Adams) 对三种沉水植物的牧食选择

报道了2005年7～9月在太湖试验基地进行的椭圆萝卜螺对沉水植物牧食的实验结果.结果表明,椭圆萝卜螺对3种沉水植物的平均牧食率为7.87mg·g-1·d-1,其中对苦草的牧食率最高(13.63 mg·g-1·d-1),马来眼子菜次之(9.66mg·g-1·d-1),轮叶黑藻最低(0.31mg·g-1·d-1),且牧食率与螺规格呈显著负相关.椭圆萝卜螺对沉水植物的牧食具有选择性,喜食苦草而较少选食其他两种沉水植物.椭圆萝卜螺的食物选择性能力与其规格有关,随着生长对沉水植物的选择性加强.探讨了椭圆萝卜螺对沉水植物的选食机理.