Rhizome Fragments Research Articles

Local adaptation and transplant dominance in genets of the marine clonal plant Zostera marina

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 242:111-118 (2002) - doi:10.3354/meps242111 Local adaptation and transplant dominance in genets of the marine clonal plant Zostera marina August Hämmerli*, Thorsten B. H. Reusch Max Planck Institute for Limnology, August-Thienemann-Str. 2, 24306 Plön, Germany *E-mail: haemmerli@mpil-ploen.mpg.de ABSTRACT: Worldwide decline of seagrass beds has increased the need for information on potential source populations for recolonization and conservation purposes. The aim of the present study was to test for local adaptation in Zostera marina, the dominant seagrass species of the northern hemisphere. To this end, we performed a reciprocal transplant experiment at the level of the genetic individual (= clone or genet) in 2 Baltic Sea populations for which the clonal structure had been mapped in detail. The treatment effects were tested on aboveground and belowground dry weight of physiologically independent rhizome fragments of replicated genets at the end of the season. We found that genets from both populations produced more biomass in their home population (local adaptation). Genets from 1 population produced more biomass overall (overall dominance) and the range of cross-site performance indicated a high degree of variability among genets within the 2 populations. Our results provide a first test for local adaptation in established seagrass genets and demonstrate home site advantage of clones that are part of a highly connected system of Z. marina populations along the Baltic Coast. KEY WORDS: Clonal plants · Local adaptation · Microsatellite · Population differentiation · Transplant experiment · Zostera marina Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 242. Online publication date: October 25, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

Application timing of asulam for torpedograss (Panicum repens L.) control in sugarcane in Okinawa island

Field and glasshouse experiments were conducted from 1995 through 1996 to evaluate application timing of asulam (methyl sulfanilylcarbamate) for torpedograss (Panicum repens L.) control in relation to plant age in sugarcane. Above‐ground shoots of torpedograss were completely controlled with asulam at 2–4 kg active ingredient (a.i.) ha−1 applied 60 or 80 days after planting (DAP) in artificially infested pots. But some newly developed rhizome buds survived after asulam application resulting in 1–25 and 76–100% or more regrowth in 60 and 80 DAP‐applied pots, respectively. Whereas the herbicide at 2–4 kg a.i. ha−1 applied within 60 DAP completely controlled above‐ground shoots, applied 80 DAP at 2 kg a.i. ha−1 it did not completely control the weed in the artificially infested field. Regrowth levels were 1–25 and 76–100% or more in 60 and 80 DAP‐applied plots, respectively. Asulam at 2–3 kg a.i. ha−1 applied 20, 40, 60 or 80 DAP in a naturally infested field completely controlled above‐ground shoots and regrowth levels were 76–100 or more, 51–75, 1–25 and 26–50% in these same DAP applied plots, respectively. The herbicide applied at 4 kg a.i. ha−1 caused chlorosis on younger sugarcane leaves (one‐leaf stage), but when applied at 2–3 kg a.i. ha−1, no injury symptoms were shown. The herbicide at 2–4 kg a.i. ha−1 applied within 60 DAP resulted in remarkably higher yield and shoot biomass of sugarcane than that applied 80 DAP. This study suggested that asulam at 2–3 kg a.i. ha−1 should be applied 60 days after planting for the maximum control of torpedograss regrowth and better yield of sugarcane. This study also indicated that torpedograss cannot be completely controlled with a single application of asulam in a naturally infested field because of rhizome fragmentation by cross plowing and distribution of rhizomes into different soil layers that require different times to emerge. The shoots emerging after asulam application could not be controlled. Another study is required to determine the interval between sequential applications of asulam for better control of torpedograss in a naturally infested field.

Influence of the structure of <i>Posidonia oceanica</i> meadows modified by bottom trawling on crustacean assemblages: comparison of amphipods and decapods

The seagrass Posidonia oceanica plays an important role as habitat for invertebrates. A correlative study was done in El Campello (SE Spain) to understand the relationships between assemblage structure of crustaceans and modification of P. oceanica structure caused by bottom trawling. We compared the changes of community structure of the most important groups of crustaceans, amphipods and decapods with changes of cover, density, detritus and rhizome fragments. Sampling was carried out in four control and four impact locations, along a gradient of degradation (17 m depth, August 1992). Multivariate analysis was used for community data (nm-MDS) and P. oceanica structure (PCA). Both groups showed a similar number of species. The amphipod community showed a clear pattern of community changes with significant differences between impact and control locations (global R = 0.298, p

Establishment and survival of three invasive taxa of the genusReynoutria (Polygonaceae) in mesic mown meadows: A field experimental study

The effect of traditional management on the initial phase of invasion into mesic mown meadows was studied in the Křivoklátsko protected landscape area in Central Bohemia, the Czech Republic. In 1996, rhizome fragments of alien species native to Asia, i. e.Reynoutria japonica, R. sachalinensis and their hybridR. xbohemica were planted in experimental plots and their establishment recorded. Established plants were then subjected to the following six treatments which simulated the management practices traditionally used in the study area: mowing twice a year, grazing by goats and sheep separately at two different intensities, and a control plot. Plant survival was recorded in the two years following planting. In order to compare the effect of the growing period, the experiment withR. japonica was conducted in two subsequent years (1995 and 1996) thus allowing observations over three years on this species. The experiment was carried out in two sites (meadows), with three blocks of treatments established in each. Significantly better establishment was found inR. japonica andR. xbohemica than inR. sachalinensis. Survival of all three taxa was negatively effected by all the management treatments applied (P<0.001). In control plots with plants of all three taxa, there was virtually no mortality during the growing seasons of either year and the number of surviving plants decreased only in the winter. In the former two species, 38.5 ± 19.4% of plants survived the first winter, the corresponding figure for the latter being only 7.2 ± 6.1%. It can be concluded that traditional management provided it is applied continuously may represent an effective barrier against the invasion of theReynoutria species. Once ceased, the potential for invasion increases and if invasion occurs, special control measures are required to eliminate the invading plants effectively.

The exploitation of heterogeneity by a clonal plant in habitats with contrasting productivity levels

Summary 1 We investigated habitat exploitation by the rhizomatous grass Elymus repens in a heterogeneous environment in both productive and unproductive habitats. We tested whether there was selective entry of rhizomes into favourable microsites or random exploration of the habitat, and whether the benefits of selective exploitation were higher in productive than unproductive habitats. 2 Trays were divided into four quadrants around a common central area. Homogeneous environments were created by planting vegetation throughout the trays; heterogeneous environments were created by planting only centre and two opposite quadrants. Contrasting productivity levels were established by fertilizing half of the trays of each environment type. A single rhizome fragment of E. repens was planted in the centre of the trays and allowed to exploit the trays for two growing seasons. 3 Elymus repens effectively exploited habitat heterogeneity at both productivity levels. However, only unproductive trays showed preferential growth of rhizomes into bare quadrants. 4 In the productive trays individual rhizomes that grew into bare quadrants showed a significantly greater production of shoots and total biomass than those that grew into vegetated quadrants. Smaller, non‐significant effects were observed at lower productivity. 5 Increased growth of primary rhizomes, once they had entered a bare quadrant, with or without selective growth into these patches, led to similar increases in heterogeneous compared to homogeneous trays at the two productivity levels (3.0 vs. 2.7). Heterogeneity was not therefore more effectively exploited at high productivity. 6 We suggest that sectorial transport of nutrients through the rhizomes, resulting in directional outgrowth of bud meristems into the bare quadrants, may have been responsible for the selective placement of rhizomes in the unproductive trays. Our results suggest that selective entry of rhizomes into favourable microsites may complement morphological plasticity in enabling rhizomatous plants to forage in heterogeneous environments.

Vegetation development in coastal foredunes in relation to methods of establishing marram grass (Ammophila arenaria)

In coastal foredunes marram grass (Ammophila arenaria) is used to stabilize windblown sand. The development of traditionally plantedAmmophila into a more natural foredune vegetation may take 5 – 10 yr. For economic reasons, traditional planting may be replaced by alternative techniques such as planting seeds or disk-harrowing rhizome fragments. In this paper, we compare the initial vegetation development of traditionally planted stands with stands established from seeds and from rhizomes.

Enzyme polymorphism in Posidonia oceanica, a seagrass endemic to the Mediterranean

Enzyme polymorphism was used to investigate genetic variability in Posidonia oceanica (L.) Delile from natural meadows around Nice (Alpes-Maritimes and Var) and among eight populations, sampled from the collection in the Port-Cros National Park, which had originated in different parts of the Mediterranean. Of the 30 enzyme systems studied only six were found useful in the isozyme studies (peroxidases, PER; glucose-phosphate isomerases, GPI; superoxide dismutases, SOD; malate dehydrogenases, MDH; catalases, CAT; glutamate dehydrogenases, GDH). The results showed that of these six only two enzymes showed enzyme polymorphism, indicating low levels of polymorphism. The small intrapopulation isozyme variability in P. oceanica meadows near Nice concurs with previous suggestions that reproduction is predominantly clonal, corresponding with previously observed infrequency of flowering in meadows. In the French meadows studied, one locus out of the eight was found to be polymorphic; this locus, moreover, showed an excess of heterozygotes. This same genetic structure found in all three meadows around Nice suggests that the greater part of these populations is not isolated, perhaps because of their practically continuous distribution along the Mediterranean coast, with dissemination by currents both of fruits and of rhizome fragments.

Seasonal variation in the intertidal seagrass Zostera noltii Hornem.: coupling demographic and physiological patterns

The considerable seasonal variation in biomass (2–130 g ash-free dry weight (AFDW) m −2) and cover of intertidal Zostera noltii Hornem. in the Zandkreek estuary (SW Netherlands) was mainly caused by changes in shoot density (1000–23000 m −2) and not in shoot size (shoot weight 1–3.6 mg AFDW, shoot leaf area 0.3–1.5 cm 2). The spring increase in shoot density was realised through continuous monopodial branching of the rhizome, which commenced when light available during low tide increased above 15 E m −2 day −1, in mid April. Branching stopped by the end of July, about 6 weeks before the onset of the annual biomass decline, due to a combination of: (a) self-shading during low tide; (b) high respiratory demand by the expanded rhizome network; (c) the seasonal decline in light availability during late summer. Nutrients were probably not limiting since concentrations in shoots remained high: 3.6% N and 0.6% P of dry weight are seasonal means. During the period of maximal biomass the primary rhizome axes decayed, leaving single shoots on short pieces of rhizome, the former secondary axes. The rapid decline in biomass from mid September onwards could be attributed to grazing by herbivorous migratory waterfowl. It was estimated that brent geese, Branta bernicla (L.), and wigeon, Anas penelope L. (about 200 and 300 birds, respectively, on the bed of 30 ha) together removed 45 g AFDW m −2 month −1, whilst autumn storms were insignificant. As established experimentally, winter survival was by single shoots enclosing an active meristem, and not by rhizome fragments without leaves. Sucrose was the main storage carbohydrate. The rhizome was the main storage organ, with maximal carbohydrate content observed in mid July (190 mg g −1 dry weight, sucrose + starch in glucose weight equivalents), and a gradual decline during autumn and winter. We estimated that the storage carbohydrates could cover 28% of the respiratory needs during winter, which would necessitate a substantial photosynthesis to meet the remaining 72%. From iteratively fitted photosynthesis-light curves we conclude that this intertidal Z. noltii population is high-light adapted compared with permanently submerged seagrasses and freshwater angiosperms: estimates for the light compensation point (LCP) and half-saturation constant ( K m) were comparatively high (July LCP and K m: 98 μE m −2 s −1 and 236 μE m −2 s −1, respectively), maximum photosynthetic rate was high ( P max: 236 μg O 2 g −1 AFDW min −1) and the initial slope of the curve was low (α: 0.63 μg O 2 g −1 AFDW min −1/μE m −2 s −1). Estimated daily oxygen balances confirmed that positive net photosynthesis was largely limited to low tide daylight in this turbid estuary (mean high tide light attenuation coefficient: 2.1 m −1).

In vitro organogenic competence of different organs and tissues of lily of the valley ‘Grandiflora of Nantes’

The in vitro organogenic competence of rhizome and flower stalk discs, flower buds and meristems of lily of the valley (Convallaria majalis L.) ‘Grandiflora of Nantes’ was studied. Except for the meristems, the other organs were all capable of organogenesis. Rhizome and flower stalk discs formed roots, while flower buds formed flower bud-like structures, and it appeared very difficult to modify the type of organogenesis. After six subcultures of the flower bud-like structures, a series of developmental stages were distinguished, i.e. regeneration of flower bud-like structures first, then leaf-like organs, and finally vegetative buds. This work pointed out the organogenic competence of the rhizome and flower stalk fragments for the first time.

Postemergence control of quackgrass [Elytrigia repens (L) Nevski] with DPX-79406 in corn (Zea mays L)

Laboratory and field experiments were established to determine the optimum dose and timing of postemergence applications of DPX-79406 for quackgrass control. Four node quackgrass rhizome fragments from each biotype were grown under controlled conditions. At the three-to-four-leaf stage, quackgrass plants were sprayed with DPX-79406 and evaluated for control. A significant response of quackgrass biotypes to DPX-79406 was evident only at lower doses. In the field, quackgrass was effectively controlled by all doses of DPX-79406. Significant growth-stage effects were observed for quackgrass shoot and rhizome dry weights in the year of application and in the year following application. There was a significant interaction between year and growth stage. In 1990, quackgrass biomass was greater when DPX-79406 was applied at the two-to-three-leaf stage of quackgrass than at the four-to-five-leaf stage. In 1991, however, the opposite occurred. Within a growth stage, the 6.25 g ha−1 dose was as effective for controlling quackgrass as 18.5 g ha−1, in both years of the study. In 1991, significant decreases in corn yield were observed for DPX-79406 doses of &gt; 12.5 g ha−1 applied at the four-to-five-leaf stage of quackgrass. For all the variables studied, DPX-79406 doses of 6.25–12.5 g ha−1 resulted in consistent control of quackgrass. Key words: DPX-79406, nicosulfuron, rimsulfuron, quackgrass, Elytrigia repens, corn, Zea mays

Hydrochory, Population Dynamics and Distribution of the Clonal Aquatic Plant Ranunculus Lingua

The dispersal and dynamics of the clonal aquatic plant Ranunculus Lingua were studied in a marginal river population in northern Sweden, where this species is dispersed exclusively by vegetative diaspores (i.e. floating rhizome fragments). The study focused on the extent and range of dispersal, relationships between dispersal and distribution of established stands of R. lingua, and between dispersal and environmental characteristics of the river (i.e. «river status»), the establishment success of vegetative diaspores, and the relative changes in ramet numbers between years. Between 0-8 and 2-9% of the total population of ramets was estimated to disperse each year. Most rhizomes were dispersed within 1 -5 km in a leptokurtic pattern. A river lake functioned as a dispersal barrier, preventing dispersal distances greater than 3 km (...)

Potential for high country pasture improvement from planting of rhizome fragments of spreading legumes

Three legumes, zigzag clover (TrijXium medium), Caucasian clover (T. ambiguum) and crown vetch (Coronilla varia) are notable for their extensive vegetative spread by underground rhizomes but slow initial establishment and low seed set. The possibility of vegetative propagation was considered. A 9-year trial showed the success of transplanting rhizome fragments of different sizes under different fertiliser regimes into hieracium-dominated fescue tussock grasslands. Initial survival and establishment was influenced by fragment size and fertiliser. Subsequent growth was similar for the three species and mainly influenced by fertiliser. Keywords high country, legumes, pasture improvement, rhizome fragments

Growth ofButomus umbellatus at a stable water level

The paper presents the results of an experiment with the cultivation ofButomus umbellatus at a stable water level of 0.8 m for 6 years. The plant growth, flowering and vegetative reproduction were measured and recorded at the end of each growing season. The species showed a great ability to reproduce vegetatively by rhizome fragments. Cultured plants ofButomus umbellatus did not show any decrease or limitation of growth or flowering caused by stable water level. The expansion of the rhizome system seems to be dependent on its spontaneous fragmentation.

Population biology of Ammophila breviligulata and Calamovilfa longifolia on Lake Huron sand dunes. III. Dynamic changes in plant community structure

Changes in vegetation and physiography of Lake Huron shoreline were studied by recording total counts and by comparing photographs taken in 1977, 1985, and 1987. In 1977, a large number of annual and biennial plant species such as Cakile edentula, Corispermum hyssopifolium, Salsola kali, Euphorbia polygonifolia, Artemisia campestris, and Oenothera biennis were found growing in association with two perennial grasses, Calamovilfa longifolia and Andropogon scoparius. Ammophila breviligulata was absent at that time, but became abundant through establishment of ramets from rhizome fragments after the storms of 1979 and 1981. Two damaging storms, one in October 1986 and the second in April 1987, wiped out almost all of Ammophila breviligulata, leaving a few remnant shoots among clumps of Calamovilfa longifolia. Observations suggest that the low density (two shoots∙m−2) of Ammophila breviligulata tillers among Calamovilfa longifolia populations on the first dune ridge has resulted from landward extensions of plagiotropic rhizomes from the once abundant Ammophila breviligulata populations on the lakeward end of the beach.

Studies of peat as the input to coalification, II. Sampling sites and preliminary fractionation

Five investigational sites in the Florida Everglades and Okefenokee Swamp have been selected in which the present vegetational cover includes a gymnosperm and various monocotyledonous and dicotyledonous angiosperms, and cores have been obtained that represent complete profiles from surface to underlying inorganic sediment. Since previous methods of fractionating peat were regarded as unsatisfactory for various reasons, a purely mechanical technique has been used in which organized plant tissue is separated from fine-grained humic matter by slurrying the peat samples in an excess of water and passing the slurry through standard 20 and 80 mesh sieves. Microscopic examination confirms that the coarse fraction consists of fragments of tissue and organs, though not all such fragments can be assigned to a specific source plant. Fragments of roots or rhizomes tend to dominate. Peats from sites in the proximity of saline waters have high sulfur contents (3–5%), most of the sulfur being combined with the organic matter. Nitrogen contents are high, most probably due to the presence of abundant amino acids condensed with the insoluble organic matter.

Temperature Factors Limiting the Spread of Cogongrass (Imperata cylindrica) and Torpedograss (Panicum repens)

Greenhouse, growth chamber, and field studies were conducted to determine effects of temperature on the potential of cogongrass (Imperata cylindricaL. Beauv. # IMPCY) and torpedograss (Panicum repensL. # PANRE) to spread beyond present distribution in the Lower Coastal Plains of Southeastern United States. Johnsongrass [Sorghum halepense(L.) Pers. # SORHA] was included in the study for comparative purposes. Growth of each species was greater with day/night temperature regimes of 30/25 C than with 27/22 or 24/18 C. Apical six-node-long rhizome fragments of all three species were killed by a 24-h exposure to −4.5 C. Johnsongrass produced at least three to five times more dry matter than either cogongrass or torpedograss. Order of interspecific competitiveness under 30/25, 27/22, and 24/18 C day/night temperature regimes was johnsongrass &gt; torpedograss &gt; cogongrass. After 2 yr, johnsongrass and torpedograss competition reduced common bermudagrass [Cyndon dactylon(L.) Pers. # CYNDA] yield by 99 and 37%, respectively, while cogongrass competition did not affect common bermudagrass yield. It is concluded that cogongrass and torpedograss are unlikely to spread into more temperate regions of the United States. However, both species are apt to become even more widespread and troublesome in the Lower Coastal Plains of Southeastern United States.

Strandline Colonization by Elymus Farctus in Relation to Sand Mobility and Rabbit Grazing

(1) The strandline of a sandy coast is a highly disturbed habitat compared with the adjacent foredunes. The catastrophic storm surge of January 1978 entirely removed the strandline communities at Holkham National Nature Reserve, Norfolk. (2) Recolonization by Elymus farctus was rapid. Seeds (caryopses) and rhizome fragments were of very similar importance as propagules in founding new clumps; seeds and rhizome fragments also contributed similarly to the overall tiller densities found in a colonizing population. (3) Subsequently E. farctus maintained a significant but tenuous presence in the strandline. Tillers were frequently killed by deep burial in sand, or swept away after erosion by wind or waves. Foredune populations were much more secure and reached higher (× 10) tiller densities, but were subject to intense rabbit grazing for much of the year. (4) Sand accretion and erosion were greatest between February and May when winds fast enough to move sand (> 4.5 ms-1) were predominantly onshore or along-shore. (5) Inflorescence and seed production were poor: in the foredunes this was because of the grazing pressure; but in the strandline flowering was even worse, because tillers rarely survived for more than one season to become vernalized. (6) Populations of E. farctus in the strandline appear to be dependent on repeated colonization by seed and rhizome fragments from the foredunes. Only rarely do conditions suitable for the initiation of a new dune ridge from the strandline population occur

Regenerative Potential of Elymus Farctus From Rhizome Fragments and Seed

(1) Both newly-germinated seedlings and shoots from single-node rhizome fragments of Elymus farctus were able to emerge after experimental burial with sand at a depth of 127 mm, but not from 178 mm. (2) Multi-node fragments had a greater probability of emergence than single-node ones at any depth, and also could emerge from greater depths. (3) Inhibition between buds on multi-node fragments led to reserves being concentrated into a single dominant shoot. Distal buds were more likely to become dominant than proximal buds. (4) Nodes of rhizomes taken from the dunes at monthly intervals showed seasonal variation in their ability to produce roots and shoots under controlled conditions. This regenerative ability was inversely related to the growth of the parent plants at the time of sampling, and could be increased by supplying exogenous nitrogen as nitrate. Seasonal patterns were still apparent, however, and concentration of total water-soluble carbohydrate was implicated as a further limiting factor. (5) Multi-node fragments are more flexible in their response to burial, because the likelihood of viable shoot production is increased and buds and resources are conserved against the possibility of further disturbance, whereas seed germination is an all-or-nothing gamble.

Growth and Development of Field Horsetail (Equisetum arvenseL.)

The growth and development of field horsetail (Equisetum arvenseL. # EQUAR) was measured outdoors using potted plants grown from one-node rhizome fragments. Shoot growth rate increased slowly after planting in March, accelerating to a maximum during July with maximas for shoot height during August and shoot number in September. Rhizome system growth rates initially followed a similar pattern to that of the shoots achieving a maximum during July. Dry matter accumulated in the rhizomes until October and declined thereafter throughout the winter. Tubers initiated during August grew in size and number until November, well beyond the period of active shoot growth and onset of senescence. The characteristics of the growth and development of field horsetail are discussed in relation to achieving weed control via cultural and herbicide treatments.

Observations on the vegetative growth pattern of speargrass ( imperata cylindrica (L.) beauv.)

The vegetative growth pattern of speargrass ( Imperata cylindrica (L.) Beauv. var. major) was studied in the greenhouse. Careful observation of plants grown from mature rhizome fragments weighing approximately 0.4 g indicated that a young plant initiates new rhizomes between the third and fourth leaf-stage. Rhizome growth is determinate (the rhizome tip turns up to form a shoot), with the apical bud forming a shoot and sub-apical buds forming rhizome branches. Under favourable conditions, apical and sub-apical buds develop simultaneously, but under stress the growth of the apical bud is favoured. Root and bud development occurs on the distal nodes of the young rhizome long after the rhizome has been formed. The significance of this growth pattern in relation to speargrass as a problem weed is discussed.