Field studies on the ecology ofBolboschoenus maritimus (L.)Palla (Scirpus maritimus L. s. l.)

In an ecological field study, plants ofBolboschoenus maritimus (L.)Palla (Scirpus maritimus L. s. l.) growing in oligohaline and in mesohaline soils were compared. Differences between both populations mainly concerning osmotic potential, water potential and ionic concentrations could be related with the salt content at both sites, whereas transpiration and photosynthesis did not differ significantly. Water potential of the cell sap was affected by several external factors.     

Rumex maritimus L. versus R. persicarioides L. (Polygonaceae) in the Western Hemisphere

A history is presented of the use and misuse of the binomials,Rumex maritimus andR. persicarioides. In light of single-character separation of the taxa, an alternative to current taxonomic usage is proposed. This treatment recognizes one species (R. maritimus, by prior choice) with two New World varieties. One change in status is made.     

The effect of submergence on tuber production and dormancy in two subspecies ofBolboschoenus maritimus

Two subspecies ofBolboschoenus maritimus (L.)Palla were cultivated in submerged and non-submerged conditions. The production of tubers, the proportion of tubers remaining dormant and the time between production and reactivation were investigated. Total tuber production was found to be dependent on subspecies and may be considered a biological character of the subspecies.Bolboschoenus maritimus ssp.compactus, a subspecies of less, flooded habitats, produced more tubers with a greater capacity for growth leaving a smaller proportion of dormant tubers. Inactivity of tubers and their reactivation after one or two years were enhanced by submergence in both subspecies. The proportion of tubers that are permanently dormant as well as the dormancy of the whole plant are important features influencing the survival of populations ofB. maritimus over periods of unfavourable conditions.     

Litter Decomposition of Scirpus maritimus L. in a Mediterranean Coastal Marsh: Importance of the Meiofauna during the Initial Phases of Detached Leaves Decomposition

Growth, senescence and decomposition rates of Scirpus maritimus were studied in a Mediterranean brackish wetland. Plant tussocks were tagged in March, 2002 and were totally dead by September, 2002. Decomposition rates were determined over 360 days using litter bag technique and mass loss, nutrient dynamics, fungal biomass, meiofauna and macroorganisms were determined. Decomposition rate of detached S. maritimus litter was 0.00196 (k, day^–1) with a 54% of mass lost observed in 1 year. The pattern of mass loss was characterized by an initial phase of fast loss of organic matter with high density of meiofauna and a decrease of oxygen content, followed by two slower phases, with no significant losses from 50 to 180 days and with 21% of mass lost from 180 to 360 days. Nitrogen (N) and phosphorus (P) content of plant litter increased during decomposition process whereas atomic C:N and C:P ratios decreased, suggesting a nutrient immobilization on plant detritus. Fungal biomass measured as ergosterol content decreased after submersion of leaves, indicating that their importance in litter decomoposition decreases in submerged leaves during the first days of decomposition. An inverse relationship (r = –0.79, P < 0.005) was observed between ergosterol content and nematodes density on S. maritimus litter. Our results suggest that in Mediterranean brackish marshes, where large amounts of dead organic matter is accumulated over the sediment surface, decomposition process is greatly affected by extremely high temperatures in summer that, if water is available, accelerates microbial activity decreasing oxygen content thus slowing decomposition. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth response of Bolboschoenus maritimus ssp. maritimus and B. maritimus ssp. compactus to different trophic conditions

Bolboschoenus maritimus (L.) Palla (=Scirpus maritimus L.) forms extensive stands in the littoral zone of small fishponds and as a weed in rice and maize fields. Within the species, two subspecies are distinguished: Bolboschoenus maritimus subsp. maritimus, B. maritimus subsp. compactus. They differ in ecology, especially in their relationships with trophic conditions and salinity of habitats. To determine growth response of these two types to different nutrient levels, we compared their seasonal development under experimental cultivation at four controlled nutrient levels. Some differences between the subspecies were found to be stable, regardless of nutrient level, namely greater amount of smaller underground tubers and more extensive rhizome system in subsp. compactus compared to less numerous larger tubers and simpler rhizome system in subsp. maritimus. In response to trophic conditions,the plants of subsp. compactus were more resistant to the conditions of the highest trophic level than those of subsp. maritimus, which were stressed. This demonstrates better adaptability and spreading ability of B. maritimus subsp. compactus at high trophic levels.     

Leaf growth,senescence and decomposition of Juncus maritimus Lam. in a coastal Mediterranean marsh

In this study, the growth, senescence, leaf loss and nutrient dynamics of Juncus maritimus were followed to examine litter decay in a Mediterranean coastal marsh. Decomposition was studied in dead leaves still attached to the plant and in leaves placed in litterbags (detached leaves/litter) on the sediment surface. The dynamics of fungi, meiofauna and epiphytes associated with detached litter were also followed. No significant differences were observed between decay rates in dead leaves attached to plants (0.0017 day⁻¹) and detached leaves (0.0015 day⁻¹) in litter bags. The percentage of ash-free dry weight lost was inversely proportional to the C:N and C:P ratios in plant detritus during decay, indicating N and P limitation for the decomposer community inhabiting decaying J. maritimus litter and uptake of these nutrients from the environment. Water availability and high temperatures on the sediment surface increased the density of meiofauna and epiphyton and decreased fungal biomass during the first 20 days of the experiment. The density of ciliates and nematodes in decomposing litter was inversely related to the C:N ratio and directly related to the percentage of AFDW lost. On the basis of these observations, it was concluded that meiofauna are primary colonizers of J. maritimus leaf litter.     

Genetic Variation and the Reproduction of Cordylanthus maritimus ssp. maritimus to Sweetwater Marsh, California

This study evaluated the genetic consequences of a reintroduction of the endangered annual plant Cordylanthus maritimus ssp. maritimus to Sweetwater Marsh (San Diego County, California). A survey of 21 enzyme loci in natural populations revealed that genetic diversity is very low and is primarily found as rare alleles at a few loci, making this species especially susceptible to the loss of alleles and heterozygosity through genetic drift. The reintroduction was performed in 1991 and 1992 by sowing seeds (collected from Tijuana Estuary) in numerous small patches of suitable habitat. For this study, leaf tissue was collected from all plants in all patches during flowering in 1995 and surveyed for genotype at the three enzyme loci that are polymorphic at Tijuana Estuary. Rare alleles were absent in 27 out of 30 patches for Pgm-1, in 17 out of 30 patches for Pgm-2, and in 10 out of 11 patches for Mdh-1. In all, half of the patches lacked any rare allele. Rare alleles tended to occur in patches with few individuals. Overall rare allele frequency was lower than in the colonies from which seeds were collected at two of the three loci, and heterozygosity was reduced. The Sweetwater Marsh population is at risk of losing most of its genetic variation at enzyme loci through the extinction of patches with few individuals. Future reintroduction attempts should attempt to create contiguous sets of patches or to periodically reseed existing patches to reduce the loss of genetic variation.     

Effect of anatomical structure on the buoyancy of achenes of two subspecies ofBolboschoenus maritimus

Differences between two subspecies ofBolboschoenus maritimus (L.)Palla (=Scirpus maritimus L.) in different habitats (littoral and terrestrial) are partly due to variations in the buoyancy of their achenes, caused by different anatomical structure of the fruits. This hypothesis was tested by comparing fruit buoyancy and anatomy of both subspecies at several localities. Plants were sampled fromBolboschoenus maritimus subsp.maritimus (plants with branched inflorescences and triangular fruits, 4 localities) andB. maritimus subsp.compactus (Hoffm.)Hejný (plants with compact inflorescences and prevailing concave fruits, 4 localities) in the Czech and Slovak Republics, andB. maritimus subsp.compactus (plants with compact inflorescences and convex fruits, 1 locality) from the coast of South Sweden. From each locality a plant with several tubers connected by rhizomes was taken and transferred into the experimental garden; from these cultivated plants (clones) mixed samples of fruits collected from each clone were used for buoyancy tests and a study of their anatomy. Fruit buoyancy was found to depend on the anatomical structure of the pericarp—the presence of aeriferous tissue in the exocarp serves as the main floating organ. This differentiated all plants studied into two groups: short-floating subsp.maritimus, with a thin or none acriferous tissue in the exocarp, and long-floating subsp.compactus with well developed aeriferous tissue. Differences in fruit buoyancy corresponds to differences in the prevailing habitat types of both subspecies studied in the inland sites: the frequent occurrence of subsp.compactus in temporarily flooded terrestrial habitats contrasts with the prevalence of subsp.maritimus in the littoral of water bodies. This is an example of intra-specific ecological differentiation leading to differentiation in wetland communities.     

Importance of native arbuscular mycorrhizal inoculation in the halophyte Asteriscus maritimus for successful establishment and growth under saline conditions

Background and aims

The biological restoration of saline habitats could be achieved by using halophyte plant species together with adapted arbuscular mycorrhizal fungi (AMF). An interesting plant to be used in restoration of saline environments, Asteriscus maritimus, is highly mycotrophic. The aim of this study was to assess the effectiveness of native and allochthonous AMF to enhance the establishment and growth of the halophyte A. maritimus under saline conditions.

Methods

We studied the symbiotic effectiveness of four AMF strains (three native fungal isolates from a saline soil and one allochthonous, from collection) in A. maritimus subjected to increasing salinity stress. We measured plant physiological parameters by which AMF may ameliorate the detrimental effects of salinity stress.

Results

A. maritimus plants showed a high mycorrhizal dependency, even in absence of salt stress. Plants inoculated with native AMF had higher shoot dry weight, efficiency of photosystem II, stomatal conductance and accumulation of glutathione than those inoculated with the collection AMF at the highest level of salinity. Moreover, at this salt level, only 30 % of A. maritimus plants inoculated with the collection AMF survived, while with the three native AMF, the rate of survival was 100 %.

Conclusions

Results points out the importance of native AMF inoculation in the establishment, survival and growth of A. maritimus plants. Inoculation with these native AMF enhanced A. maritimus salt tolerance by increasing efficiency of photosystem II, stomatal conductance and glutathione content and by reducing oxidative damage. Thus, the use of adequate native AMF inocula could be a critical issue for success in recovering saline degraded areas.     

Kinetic study of the velum formation by Saccharomyces cerevisiae (beticus ssp.) during the biological aging of wines

The main objetive of this work was to evaluate and model the biofilm growth of the Saccharomyces cerevisiae (beticus ssp.) yeast during the biological aging of some types of wines. Thus, we have study how the biofilm growth, the glycerine is consumed and the acetaldehyde is produced, and how this phenomena are affected by the media ethanol concentration (0–17%, v/v), under experimental conditions similar to the industrial ones. In consequence, the growth of the S. cerevisiae (beticus ssp.) biofilm on the surface of the liquid was studied and kinetically modelled. Growth curves were fitted by using general kinetic models that include biomass and substrate inhibition factors. The alcohol content of the medium for the fastest growth rate of biofilm was found to be 4.3%, v/v. The proposed kinetic models for biomass growth, glycerine consumption and acetaldehyde formation fit well with the experimental data.The growth kinetics of S. cerevisiae beticus ssp. in biofilm phase presents a typical discontinuous microbial growth profile (with lag, exponential and stationary phases). The glycerine consumption is directly related to the substrate concentrations (ethanol and glycerine). Finally, the rate of acetaldehyde formation suggests a model associated with the rate of microbial growth, which is modified by a substrate-dependent factor. The suggested model can be used for optimization and control processes of biological aging of wines.     

Development and polymorphism of Vigna unguiculata ssp. unguiculata microsatellite markers used for phylogenetic analysis in asparagus bean (Vigna unguiculata ssp. sesquipedialis (L.) Verdc.)

Asparagus bean (V. unguiculata ssp. sesquipedialis), a specific form of cowpea (V. unguiculata L. Walp.), is cultivated as a vegetable crop throughout eastern and southern Asia for its tender long pods. Little is known about the genetic relationship between asparagus bean and the broader species, particularly the dominant ssp. unguiculata. We report here the development and transferability of simple sequence repeat (SSR) markers, over 40% of which are EST-derived, from ssp. unguiculata to asparagus bean and the use of a subset of the polymorphic markers to assess the genetic diversity of asparagus bean cultivars from diverse geographic origins across China. A total of 410 EST derived SSR (eSSR) markers and 600 SSR markers derived from cowpea genespace sequences (GSS) were developed, with a cross-subspecies transferability of 100% and 98.5%, respectively. In a recombinant inbred line population of asparagus bean, a 1:1 segregation was observed for most loci. Principal coordinate analysis (PCA) and phylogenetic clustering based on 62 alleles detected by 14 polymorphic SSR markers distinguished ssp. unguiculata and sesquipedialis into separate groups. Improved asparagus bean cultivars in China generally have a narrow genetic basis compared with landraces varieties. This suggests that asparagus bean breeding programs need to consider utilizing landrace germplasm to enhance genetic variability and ensure long-term gains from selection and reduce genetic vulnerability to pathogen/pest epidemics. Because of their transferability across subspecies, the SSR markers described in this study could be effectively employed in cross-subspecies trait introgression breeding from ssp. unguiculata to sesquipedialis.     

Primary production and nutrient budgets of Sarcocornia perennis ssp. alpini (Lag.) Castroviejo in the salt marsh of the Palmones River estuary (Southern Spain)

Biomass, primary production and nutrient budgets associated to Sarcocornia perennis subspecies (ssp.) alpini were studied in the Palmones River estuary salt marsh (Southern Spain) to evaluate the nutrient sequestration capacity of the low marsh. Above- and belowground living and dead biomass, as well as carbon, nitrogen and phosphorus content were monitored during 1 year. Additionally, the fate of aboveground detritus was evaluated in an experiment on litter decomposition. The detritus production of S. perennis ssp. alpini was almost equivalent to its annual primary production indicating a rapid turnover of biomass. We calculated that only 12% of the aboveground detritus was exported out of the low marsh while the rest was decomposed in the sediment with a rate of 0.8 year⁻¹. Changes in concentrations of total carbon, nitrogen and phosphorus in the sediment showed patterns related to S. perennis ssp. alpini belowground biomass. Our results suggested that the sediment functions as a net sink for nutrients accumulating 550 g C m⁻² year⁻¹, 55 g N m⁻² year⁻¹, and 13 g P m⁻² year⁻¹.     

Characterization of polymorphic microsatellite DNA markers for Acacia saligna (Labill.) H.L.Wendl. (Mimosaceae)

A genomic library was constructed and 10 novel polymorphic microsatellite markers developed for Acacia saligna, a species complex being developed for agroforestry across southern Australia. Polymorphism was investigated for these markers in 30 individuals from two subspecies. Alleles per locus averaged 4.0 for ssp. saligna and 5.2 for ssp. lindleyi. Population specific alleles were detected for all loci. The microsatellite markers will be used for diagnostic assessment of the four main subspecies of the species complex.     

Ecosystem Engineering by Plants on Wave-Exposed Intertidal Flats Is Governed by Relationships between Effect and Response Traits

In hydrodynamically stressful environments, some species—known as ecosystem engineers—are able to modify the environment for their own benefit. Little is known however, about the interaction between functional plant traits and ecosystem engineering. We studied the responses of Scirpus tabernaemontani and Scirpus maritimus to wave impact in full-scale flume experiments. Stem density and biomass were used to predict the ecosystem engineering effect of wave attenuation. Also the drag force on plants, their bending angle after wave impact and the stem biomechanical properties were quantified as both responses of stress experienced and effects on ecosystem engineering. We analyzed lignin, cellulose, and silica contents as traits likely effecting stress resistance (avoidance, tolerance). Stem density and biomass were strong predictors for wave attenuation, S. maritimus showing a higher effect than S. tabernaemontani. The drag force and drag force per wet frontal area both differed significantly between the species at shallow water depths (20 cm). At greater depths (35 cm), drag forces and bending angles were significantly higher for S. maritimus than for S. tabernaemontani. However, they do not differ in drag force per wet frontal area due to the larger plant surface of S. maritimus. Stem resistance to breaking and stem flexibility were significantly higher in S. tabernaemontani, having a higher cellulose concentration and a larger cross-section in its basal stem parts. S. maritimus had clearly more lignin and silica contents in the basal stem parts than S. tabernaemontani. We concluded that the effect of biomass seems more relevant for the engineering effect of emergent macrophytes with leaves than species morphology: S. tabernaemontani has avoiding traits with minor effects on wave attenuation; S. maritimus has tolerating traits with larger effects. This implies that ecosystem engineering effects are directly linked with traits affecting species stress resistance and responding to stress experienced.     

Evaluation of phytotoxic potential and identification of phytotoxic compounds in Rumex maritimus

Rumex maritimus (Polygonaceae) is an annual herb and is well known for its use in medicinal treatments. Although the pharmacological properties of R. maritimus are well documented, no phytotoxic activity of R. maritimus has yet been found. Therefore, we investigated the phytotoxic potential of R. maritimus to identify phytotoxic compounds. Inhibitory activity was found in aqueous methanol extracts of R. maritimus on the seedling growth of cress, rapeseed, barnyard grass, and foxtail fescue, in which inhibition increased with increasing extract concentration. Two compounds were isolated using chromatography, and using spectroscopy their structure was determined as 5,7-dihydroxyphthalide and altechromone A. 5,7-Dihydroxyphthalide significantly inhibited cress seedling growth by 27.2–43.0% of control seedlings at 3 mM, whereas altechromone A inhibited seedling growth by 65.4–66.3% at 0.01 mM. The concentrations required for 50% inhibition of cress seedling growth were 1.73–2.48 mM for 5,7-dihydroxyphthalide and 0.66–1.41 mM for altechromone A. These results indicate that the compounds 5,7-dihydroxyphthalide and altechromone A may contribute, to a certain extent, to the phytotoxic activity of R. maritimus.     

Gymnopilus maritimus (Basidiomycota, Agaricales), a new species from coastal psammophilous plant communities of northern Sardinia, Italy, and notes on G. arenophilus

The new species Gymnopilus maritimus is described from coastal plant communities of Juncus maritimus, growing on sandy soil or on decaying plants, from northwestern Sardinia (Italy). The distinguishing features of G. maritimus are: (1) an unusual habitat, (2) robust basidiomata, (3) mild taste, and (4) big and strongly warted spores. The new species is compared with the micromorphologically similar species G. fulgens sensu auct. Brit. p.p. and the biogeographically and ecologically similar species G. arenophilus, as well as with other European species. A photograph of fresh material, drawings of the main micromorphological features, and FESEM and optical microscope microphotographs of basidiospores are added. Furthermore, some notes on micromorphological characters of G. arenophilus are presented and its distribution area enlarged with a record from France. A key for the European species of Gymnopilus morphologically, ecologically, and/or biogeographically related to G. maritimus is presented. The phylogeny inferred from ITS rDNA sequences revealed that G. maritimus represents an independent species and that it is not related to G. arenophilus or G. fulgens. It is the sister group of the clade containing G. imperialis and G. spectabilis, but with a bootstrap support below 50%. The characters shared by the species in this clade are: (1) robust basidiomata, (2) pileus fibrillose or scaly-fibrillose, and (3) spores longer than 8 μm, dextrinoid and strongly warted. Gymnopilus imperialis and G. spectabilis differ by the basidiomata with membranous ring in the stem, living on conifers or decaying wood, and having narrower or wider spores, respectively. Taxonomical novelties: Gymnopilus maritimus Contu, Guzm.-Dáv., A. Ortega & Vizzini     

Variability of Essential Oil Content and Composition of Origanum vulgare L. Populations from a North Mediterranean Area (Liguria Region, Northern Italy)

Native populations of Origanum vulgare L. from the Liguria andEmilia regions of northern Italy were analysed for essentialoil content and composition. Morphological characters suggestedthat the Ligurian samples belonged to the ssp. viride. The essentialoil content of inflorescences ranged from less than 5 mg g^-1inthe samples from Emilia, to more than 50 mg g^-1in some Liguriansamples, values similar to those reported for ssp. hirtum fromsouthern Italy. Sixty-four compounds were identified in theessential oil. The samples were allotted to three main groupson the basis of oil composition: the first group had a highcontent of components belonging to the carvacrol/thymol biosyntheticpathway; the second was characterized by a different sesquiterpenecomposition and a high linalool content; and the third, includingthe two samples of ssp. vulgare from Emilia, was characterizedby the presence of abundant sesquiterpenes. The high essentialoil content of the samples studied, and the presence of someparticular morphological characters suggest that the taxonomyof O. vulgare, especially in its western distribution area,needs further investigation. Linalool types, although oftennot considered as ‘typical oregano’, may be usefulin promoting wider utilization of the biodiversity of this species.Copyright 2000 Annals of Botany Company Oregano, Origanum vulgare L., ssp. viride, ssp. vulgare, ssp. hirtum, essential oil, gas chromatography, mass spectrometry, genetic resources, chemotypes, quality, Mediterranean     

A palynological study of the genus Nepeta L. (Lamiaceae)

The pollen morphology of forty taxa of the genus Nepeta L. was studied and documented in detail using light microscopy (LM) and scanning electron (SEM) microscopy in this study. Nepeta L. pollen grains are small to large (P = 18.64–63.46 μm, E = 15.62–46.33 μm), suboblate to perprolate (P/E = 0.86–2.09) in shape and hexacolpate (very rarely tetracolpate) with granular membranes. Alternate position of colpi occurs in six Nepeta taxa, N. nuda ssp. glandulifera, N. concolor, N. crinita, N. congesta var. cryptantha, N. stricta var. stricta and N. sibthorpii ssp. tumeniana. In examinations of exine ornamentation with SEM, two types of pollen grains were recognized: (1) type I, with microreticulate sculpture; and (2) type II with bireticulate sculpture, type I and II to be divided into two and five subtypes, respectively. In the two taxa with microreticulate pattern, N. pilinux and N. sulfuriflora, a tendency towards a bireticulum could be recognized due to traces of secondary tectal connections. The bireticulate exine ornamentation is characterized with varying characteristics of the primary muri and secondary reticulum. Pollen morphology within the genus is compared with infrageneric relationships.     

Effect of the change of leaf angle arrangement on productivity of maize (Zea mays L.) stands

Leaf angles, frequency distribution of leaf area inclinations, leaf area index, amount of intercepted radiation, biological, vegetative and grain yields and grain yield proportion of biological yield were determined in maize stands of two population densities, 55 555 plants ha^?1 (S ₁), and 80 000 plants ha^?1 (S ₂). Also the effect of the artificial change of leaf angle upon these indices was studied. We classified normal maize stand (N) as the interstage between a planophile and a plagiophile type of canopy, that with artificially changed leaf angle (V) as an erectophile type of canopy. The relative interception of the incoming radiation in the variantsV S ₁ andV S ₂ was lower than in the variantsN S ₁ andN S ₂. The variantsV in comparison with variants N increased grain yield and biological yield.     

Effects of nutrients on mosquitoes and an emergent macrophyte,Schoenoplectus maritimus,for use in treatment wetlands

Schoenoplectus maritimus (alkali bulrush) has desirable attributes, such as a short growth habit (height of mature stands < 1.5 m) and annual senescence, for a potential alternative to tall (height > 3 m) emergent macrophytes in shallow constructed treatment wetlands treating ammonium‐dominated wastewater. The effects of different ammonium nitrogen (NH₄‐N) levels on alkali bulrush growth and its ability to take up nutrients from the wastewater, as well as on mosquito production, across the range of NH₄‐N found in constructed wetlands of southern California are unknown. We evaluated the effects of enrichment with NH₄‐N on mosquito production and on the nutrient uptake and growth of alkali bulrush in two studies. Overall, significantly greater numbers (> 50%) of immature mosquitoes (mainly Culex tarsalis) were found in mesocosms enriched with NH₄‐N than in mesocosms receiving ambient (<0.3 mg/liter) NH₄‐N. High NH₄‐N enrichment (up to 60 mg/liter) did not adversely impact the height and stem density of S. maritimus, although a significant decrease in biomass was observed at the highest enrichment level. Nitrogen uptake by alkali bulrush increased directly with NH₄‐N enrichment, whereas carbon was conserved in the above‐ground biomass across the enrichment gradient. Alkali bulrush is recommended for use as part of integrated mosquito management programs for moderately enriched, multipurpose, constructed treatment wetlands that improve water quality as well as provide wetland habitat for waterfowl.