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.     

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.     

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     

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.     

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.     

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.     

Induction of synchronous secondary somatic embryogenesis in Camellia sinensis (L.) O. Kuntze

Nutritional effect of nitrate salts of potassium and ammonium, together with different concentrations of sulphate salts of aluminium, potassium, magnesium, and ammonium on secondary somatic embryogenesis, wereinvestigated. Nitrate salts of potassium (9.39 mmol/L) and ammonium (10.31 mmol/L) with only 1.5 mmol/L potassium sulphate produced maximum number of synchronous secondary embryos (i.e. 20-25 secondary embryos per primary embryo in 91.6 percnt; responsive explants).Of the different factorial combinations of glutamine, BAP, and IBA tested, maximum number of synchronous secondary embryos developed on a medium supplemented with 8.88 μmol/L BAP, 0.98 μmol/L IBA and 10 mmol/L glutamine.Synchronous and normal development of secondary embryos could thus be obtained when optimal concentrations of PGRs, glutamine, nitrates, and salts of potassium sulphate were combined together.Germination of the embryos (up to 52 percnt;) was acheived only when sulphate salts of potassium were removed from the medium.     

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.     

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.     

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.

     

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.     

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。     

Growth of three submerged plants below different densities of Nymphoides peltata (S. G. Gmel.) Kuntze

We evaluated one-sided competition from the floating-leaved plant Nymphoides peltata (non-indigenous in Sweden) on three submerged plant species, Ceratophyllum demersum, Elodea canadensis and Ranunculus circinatus, in a controlled experiment. The three submerged species were allowed to grow for 21 days in the absence of N. peltata and with the species present at densities of approximately 33, 66 and 100% cover. All species retained a positive relative growth rate (RGR) based on length at all N. peltata densities, but responded with negative growth based on weight for several treatments. C. demersum achieved RGR of 0.03 day⁻¹ in the absence of N. peltata, RGR of 0.02 day⁻¹ in the lowest N. peltata density but negative RGR in the two denser treatments. E. canadensis responded similarly with RGR of 0.04 day⁻¹ in the absence of N. peltata, RGR of 0.01 day⁻¹ in the lowest N. peltata density and negative RGR in the two denser treatments. R. circinatus, on the other hand, never achieved positive RGR based on weight. These results suggest that one-sided competition from floating-leaved plants has a profound effect on the submerged plant community.     

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.     

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.     

Micropropagation of tea (Camellia sinensis (L.) O. Kuntze) using Thidiazuron

The effect of thidiazuron (TDZ) on the micropropagation of Camellia sinensis (China hybrid) was compared with that of benzylaminopurine (BAP) using nodal segments from in vitro raised seedlings. Extremely low concentrations of TDZ (1pM–100nM) alone were effective in inducing shoot bud proliferation and maintaining high rates of shoot multiplication on hormone-free media. On the other hand, higher concentrations of BAP (1–10M) and its continued presence were required to initiate and sustain shoot proliferation. While wider ranges of BAP combined favourably with auxins like NAA or IBA, only specific combinations of TDZ and NAA were effective for shoot proliferation. TDZ treated explants yielded healthy shoots, with sturdy leaves, even during the initial stages of growth, whereas, the effect of BAP was cumulative over subcultures in attaining a high proliferative rate.     

In vitro clonal propagation of tea (Camellia sinensis (L.) O. Kuntze)

A system for in vitro clonal propagation has been developed in tea plants. Shoots obtained from primary explants were induced from terminal buds and axillary buds of mature field-grown plants. Cultures were initiated from both types of explants on Murashige and Skoog (MS) medium supplemented with 10% coconut milk (CM), 200 mg l^-1 of yeast extract (YE), 1.4 M indoleacetic acid (IAA) and 17.8 M benzyladenine (BA). The shoot tips were multiplied on 1/2 strength MS medium containing 10% CM, 2.9 M IAA and 17.8 M BA. The larger shoots were separated after multiplication and rooted on 1/2 MS medium supplemented with 11.4 M ascorbic acid and 34.5 M indolebutyric acid (IBA). A pretreatment of the plants with an aqueous solution of 493 M IBA greatly increased the frequency of rooting. More than 60% of the rooted plants have been transferred to soil successfully.Abbreviations BA benzyladenine - IAA indoleacetic acid - IBA indolebutyric acid - YE yeast extract - CM coconut milk - MS Murashige and Skoog medium (1962)     

Characterization of fluoride uptake by roots of tea plants (Camellia sinensis (L.) O. Kuntze)

Backgrounds and aims

Tea plants (Camellia sinensis (L.) O. Kuntze) accumulate high fluoride in the leaves whereas the mechanism on its uptake is poorly understood. The measured F^? uptake was compared to calculated uptake from transpiration rates assumuing no discrimination between F^? and water to characterize the property of F^? absorption by tea plant roots.

Methods

The F^? uptake was examined by depletion method under variable external F^? concentrations, pH, temperature, relative air humidity, anion channel blockers and metabolism inhibitors in solution experiments.

Results

Measured F^? uptake rates were significantly larger than those calculated from transpiration rates regardless of external F^? concentrations, uptake durations, relative humidity, and solution pH. The measured and net F^? uptake (subtracting that calculated from transpiration rate from the measured uptake) were reduced by low temperature and inhibited by anion channel and metabolism inhibitors anthracene-9-carboxylic acid (A-9-C), niflumic acid (NFA), and carbonylcyanide m-chlorophenylhydrazone (CCCP) but not by dihydro-4, 4′ diisothiocyanostilbene-2, 2′-disulphonic acid (DIDS). The F^? uptake showed biphasic response patterns, following saturable Michaelis–Menten kinetics in the range of low external F^? (below 100 μmol?L^?1) while increased linearly with external supply in the range of high concentrations.

Conclusion

The uptake of F^? by roots of accumulator tea plants was likely an active process and energy-dependent. This helps to explain why tea plants are able to accumulate considerably high F^?.     

Embryological observations on Tipuana tipu (Benth.) O. Kuntze (Dalbergieae,Papilionaceae)

Abstract

The anther and ovule development of Tipuana tipu is described. Some embryological aspects previously not reported for the family have been pointed out, i.e. the Basic type of anther wall development; the constant occurrence of several megasporo-cytes undergoing meiosis, the concurrent development of more than one megaspore and finally the coexistence of three or four mature gametophytes in the same ovule.     

In vitro regeneration of Camellia sinensis (L.) O. Kuntze by somatic embryogenesis

Within 3 weeks of culture, excised cotyledon expiants of Camellia sinensis (L.) O. Kuntze produced somatic embryos without intermediate callus when cultured in Murashige and Skoog's basal medium with 30 g^–1 sucrose. In medium without plant growth regulators, up to 60% of the cultures developed somatic embryos. Embryogenic competence was reduced by increasing concentrations of plant growth regulators tested (i.e. kinetin, 6-benzylaminopurine, and indole butyric acid). The somatic embryos developed, grew to maturity without being subcultured within 6–8 weeks. Secondary embryogenesis was not observed. Germination of isolated mature somatic embryos was low in medium without plant growth regulators. Up to 53% and 60% germination occurred when medium impregnated with kinetin at 1.8 mgl^–1 or 1.0 mgl^–1 6-benzylaminopurine were used respectively. Callus was also routinely produced when cotyledons were cultured in MS basal medium with auxins (2,4-dichlorophenoxyacetic acid and indole acetic acid). Callus induction was however, also achieved in plant growth regulator free medium. Indirect somatic embryogenesis was not induced in the present study.Abbreviations K kinetin - BAP 6-benzylaminopurine - IBA indole butyric acid - IAA indole acetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - NAA Naphthalene acetic acid - Fe-EDTA Ethylenediaminetetra-acetic acid (Ferric monosodium salt)