Superficial Root Research Articles

Neotropical Monogenoidea. 23. Two new species of Gyrodactylus (Gyrodactylidae) from a Cichlid and an Erythrinid fish of Southeastern Brazil

Two new species of Gyrodactylus Nordmann, 1832 (Platyhelminthes, Monogenoidea) are described from fishes collected from southeastern Brazil. Gyrodactylus geophagensis n. sp. was collected from the body surface of the "cará", Geophagus brasiliensis (Quoy and Gaimard, 1824) (Cichlidae), from the Rio da Guarda, state of Rio de Janeiro; its major diagnostic features are the morphology of the anchor with a short, truncate superficial root and the shape of the hooks - with a long, delicate shaft. Gyrodactylus trairae n. sp. parasitizes the body surface of the "traíra", Hoplias aff. malabaricus (Bloch, 1794) (Erythrinidae), from the rio Guandu, state of Rio de Janeiro and can be easily differentiated from other species of the genus by having a thin, dorsal bridge, connecting the superficial bar with the spathulated shield. These are the first species of Gyrodactylus formally reported from Brazil. Presently, 26 species of Gyrodactylidae are known from freshwater fishes in the neotropical region; a list of these species is provided.

ROOT FORM AND STABILITY OF OUTPLANTED TREES: RESULTS OF A 1989 SURVEY

Summary During 1989, an investigation into the growth and stability of black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.) was performed in eight plantations aged three to nine years in the Lower St. Lawrence-Gaspe region. The highlights of the field work showed that air pruning of taproots and primary lateral roots of containerized black spruce seedlings resulted in the formation of replacement roots. Superficial root systems were more abundant in black spruce than in jack pine saplings, while the normal type of root system, with roots developing from the top, middle and lower portions of the plug roots, was dominant in jack pine saplings. Slight differences were found in the number of L-shaped, spiralled and grafted roots due to differences in species. In outplanted bareroot seedlings, the plunging or vertical root component was important only in jack pine.

AcremoniumSpecies as the Causal Agent of Muskmelon Collapse in Spain

Over the last decade, a new disease of muskmelon (Cucumis melo) has appeared in the coastal Mediterranean areas of Spain where early melons are produced in the field. The economic losses are severe, and the disease is spreading to new areas. The aim of this research was to describe the disease and conduct Koch's postulates to show an Acremonium sp. to be the causal agent. This fungus has not previously been reported to cause a similar disease on melon. The obvious aboveground symptom of the disease is a sudden collapse of the plant when the first fruit is ripening. Root symptoms appear soon after planting and include yellow discoloration and corking of the upper root, generalized death of secondary roots, and continuous production of superficial roots

How Repair Cementum Becomes Attached to the Resorbed Roots of Human Permanent Teeth

Human premolars extracted for orthodontic reasons were fixed with a mixture of formaldehyde and glutaraldehyde and processed for light and transmission electron microscopy. About 15% of all available teeth showed signs of superficial root resorption. Quantitatively, the resorption lacunae were more frequent at the apical third of the root, when compared to the mid-root and the cervical levels. Qualitatively, the resorption areas appeared as shallow irregular concavities. The degree of resorption and/or repair varied considerably both within and between sites, ranging from arrested resorption to advanced repair. An about 1- to 2-microns-thick seam of exposed collagen fibrils of the residual dentinal matrix lined the resorbed root surfaces in the arrested stage of resorption. A particular class of mononuclear cells repopulated these surfaces and commenced to attach newly produced collagenous matrix fibrils to the exposed dentinal matrix. Increasing fibril formation and bundling resulted in a collagenous fiber fringe oriented perpendicular to the bottom of Howship's lacunae. Following the implantation and establishment of this initial fiber fringe, the junctional zone between the two matrices and further portions of the repair matrix became progressively obscured by a fine granular and electron-dense material, indicating the advancing front of mineralization. In addition, the junctional zone later attained a high degree of electron density and basophilia. Subsequently formed matrix derived from cementoblasts was structurally heterogeneous and resembled cellular intrinsic fiber cementum (CIFC). It is suggested that the initially produced matrix along resorbed root surfaces closely resembles that seen during initial formation of acellular extrinsic fiber cementum (AEFC), whereas further apposition results in a tissue with the characteristics of CIFC.

The functional ecology of Empodisma minus (Hook, f.) Johnson & Cutler in New Zealand ombrotrophic mires.

Mires dominated by restionaceous rushes occur in valley and basin sites around New Zealand. The main restiad species is Empodisma minus which produces a surface mat of negative geotropic roots which eventually form a principal part of the underlying peat. Comparison of the peat chemistry of four such mires with a minerotrophic mire w*as consistent with their suspected ombrotrophic status. The base-exchange capacity achieved (704 + 23.3 mequiv m-2 of the surface) by the superficial roots of Empodisma is at least as great as that of the New Zealand Sphagnum cristatum which is not dominant in ombrotrophic conditions. The widespread development of a hummock and hollow microtopography may be associated with higher rainfall regimes and the propensity of Empodisma for directing most incoming rainfall (on which its nutrient economy depends) down its wiry stems.

Relações hídricas em seringal no município de Piracicaba, SP

Em um estudo das relações hídricas de um seringal de 5 anos de idade, implantado na região sudeste do Brasil em 1984 são mostradas variações de umidade do solo, potencial da água no solo, distribuição radicular, interceptação de precipitação pluvial e escoamento superficial. Resultados indicam a estreita faixa de retenção de água da terra roxa estruturada e a alta correlação entre as variações de potencial da água no solo e a distribuição radicular. O seringal apresentou um sistema radicular com raízes superficiais (0-30cm) se estendendo até a projeção das copas e raízes profundas, atingindo mais de 2,5m. O perfil de solo não apresentou escoamento subsuperficial de água ao longo do declive de 10%, mas apresentou significantes perdas superficiais, chegando a 50% da chuva em dias com superfície do solo muito úmida. A interceptação média das copas não passou de 5% da precipitação pluvial.

Pellucidhaptor eriensis n.sp. and Pellucidhaptor thelostea n.sp. (Monogenea: Dactylogyridae) from catostomids (Cypriniformes) found in Lake Erie, Ontario, Canada

A collection of dactylogyrid Monogenea from catostomid fishes taken in Lake Erie, Ontario, Canada, included Pellucidhaptor eriensis n. sp. from Carpiodes cyprinus and Moxostoma macrolepidotum; P. thelostea n.sp. from Moxostoma macrolepidotum and M. anisurum; P. angularis Kritsky and Hathaway, 1969 from Carpiodes cyprinus; P. micracanthus Kritsky, Leiby, and Shelton, 1972 from Carpiodes cyprinus; P. moxostomi Mergo and White, 1982 from Moxostoma anisurum (new Canadian record) and P. nasalis Dechtiar, 1969 from Catostomus commersoni. Pellucidhaptor eriensis is differentiated from other Pellucidhaptor species by the shape of the superficial root of the dorsal hamuli, the shape of the dorsal bar, and the configuration of the male copulatory apparatus. Pellucidhaptor thelostea is readily distinguished from other members of the genus by the sclerotized "wishbone"-shaped support of the male copulatory organ. Supplementary data are provided for the previously described species and an updated list of parasite–host records is included.

Salsuginus yutanensis n. sp. (Monogenea: Ancyrocephalidae) from Fundulus sciadicus in Clear Creek of Eastern Nebraska

Salsuginus yutanensis n. sp. (Monogenea: Ancyrocephalidae) is described from the gills of the plains topminnow, Fundulus sciadicus Cope, from Clear Creek in eastern Nebraska. Salsuginus yutanensis is distinguished from previously described species by having a shorter accessory piece and different hamulus proportions, especially in the relative lengths of deep and superficial roots. In addition, the angles between deep and superficial roots distinguish S. yutanensis from several congeners.

Productions sous tunnel ou au champ: influence sur la survie de plants de chênes après plantation

The use of polyethylene covered greenhouse has proven to be an effective method to promote the growth of seedlings. Could this improvement of the rate of growth affect seedling quality and their field performance after planting? To test this hypothesis, experimental plantations were made with two species of oak (Quercus macrocarpa Michx. and Q. rubra L.). Survival and growth in height after planting were compared between seedlings produced in one season under polyethylene or in two years in open field conditions. For both species, survival percentages of the greenhouse-cultivated stock were superior to those of the field-cultivated seedlings. Analysis of the variation of the survival percentages during weeks and months following outplantings leads us to believe that the field-cultivated seedlings are probably subjected to a greater transplanting shock. The production of large seedlings, in only one season under greenhouse condition, promotes the development of a more superficial root system. Root damage at lifting is less important and the chance of successful establishment after planting are improved. Key words: Greenhouse, plantation, Quercus sp., seedling production, seedling quality, survival.

Root Architecture of Shrubs and Saplings in the Understory of a Tropical Moist Forest in Lowland Panama

Entire root systems of 2-3 m tall plants in tropical moist forest near Barro Colorado Island, Panama were excavated and measured. We studied 3-4 plants, each, of the canopy and subcanopy species Trichilia tuberculata (Meliaceae), Prioria copaifera (Caesalpinoideae), Hirtella triandra (Chrysobalanaceae), and Tetragastris panamensis (Burseraceae); the immature treelet Faramea occidentalis (Rubiaceae); and the mature shrubs Piper cordulatum (Piperaceae), Psychotria horizontalis (Rubiaceae), and Hybanthusprunifolius (Violaceae). Root and crown architecture of intermediate specimens was illustrated. Shrubs had shallower root systems with a higher proportion of total surface area at 0-20 cm depth than tree saplings. Shrubs also had greater root surface area, both absolutely and relative to leaf area. An analysis of Coster's data for 6-month old plants of 44 species grown in a Javanese garden confirmed that shrubs tend to have relatively shallower root systems than tree species. We examine several explanations of differing root architecture for these life forms based on adult requirements for water, support, and nutrients. We speculate that reproduction creates greater nutrient demands in shrubs than in saplings. By analogy with community patterns on very poor soils, a well developed, superficial root system increases nutrient absorption from the relatively richer upper stratum. The tradeoff appears to be reduced resistance to water stress in shrubs compared with tree species.

Ultrastructural study on human root caries.

Superficial root caries lesions of incisors and premolars of 24 patients aged 52-60 years were studied by scanning electron microscopy and transmission electron microscopy. In the predominantly gram-positive bacteria of the root dental plaque, a great number of corncob configurations were observed. Bacterial infiltration into cementum occurred without any gradient of demineralization and mainly followed the borders between calcified cementum bundles as well as incremental lines. The narrow channels which were filled initially by a single row of gram-positive bacteria broadened progressively with simultaneous destruction of the apatite minerals and the collagenous matrix. Root dentin invasion showed great similarities to coronal dentin with an important gradient of demineralization. In the deep layers, sclerosed tubules contained sometimes rhombohedral crystals. In more superficial layers, bacterial invasion occurred initially in still partially sclerosed tubules. Tubular lumens as well as lateral side branches which had lost their peritubular dentin were filled with gram-positive microorganisms. An important diffuse destruction of the apatite minerals was observed at this stage in the intertubular dentin which still presented typical cross-banded collagen fibrils. The confluence of enlarged dentinal tubules filled by numerous microorganisms led to large bacterial zones with complete destruction of root dentin.

Rooting patterns of Rumex species under drained conditions

Root development and architecture were studied in three Rumex species growing in a perforated soil system in the greenhouse. Distinct differences in vertical root distribution under drained conditions were found among the three species. Rumex acetosa and R. palustris had a relatively superficial root pattern, whereas in R. crispus much of the root growth was concentrated in lower soil layers. In the upper soil layer the relative growth rate of the roots of R. palustris was significantly larger than that of the other species. A relation between the characteristic rooting patterns under drained conditions and the Rumex zonation in the field is discussed.

Ecological Observations in the Dwarf Cloud Forest of the Luquillo Mountains in Puerto Rico

Five species accounted for 95 percent of the stems of at least 10 cm DBH on three plots totaling 0.22 ha in the dwarf cloud forest of the Luquillo Mountains in Puerto Rico. Mean density for stems of at least 10 cm DBH was 3671 ? 516 stems/ha, and mean basal area was 49.1 ? 8.2 m2/ha. The aboveground woody biomass on two small plots of 0.0036 ha, one located on a ridge and the other 100 m to the leeward, was 48 and 110 t/ha, respectively. Leaf area index on the ridge was 1.99 m2/m2, leaf biomass was 288 g/m2, and specific leaf weight was 14.5 mg/cm2. Mean annual litterfall rates averaged only 0.85 g/m2/day (3.10 t/ha/yr), of which 79 percent was leaf litter, 9 percent wood litter, and 12 percent miscellaneous material. The rate at which nutrients returned to the soil (kg/ha/yr) averaged 23.9 for nitrogen, 0.7 for phosphorus, 4.3 for potassium, 16.3 for calcium, and 7.6 for magnesium. The annual increment in tree diameter was low, averaging only 0.03 ? 0.01 cm/yr. For trees at least 2.5 cm in diameter, aboveground biomass accumulated at an average rate of 45 g/m2/yr. Net primary productivity was 3.84 t/ha/yr. ZONATION OF FORESTS WITHIN MONTANE HABITATS on tropical islands is condensed into a narrow altitudinal range, a phenomenon known as the Massenerhebung effect. One example is the Luquillo Mountains of northeastern Puerto Rico, which abruptly rise to 1060 m in only 15 km. As elevation increases, the number of arborescent stems/ha increases, while decreases occur in average height of dominants, average DBH, basal area/ha, and number of species per unit area (White 1963). The dwarf forest, an association in the lower montane rain forest (sensu Holdridge 1967, Ewel & Whitmore 1973) on the upper slopes and summits of the Luquillo Mountains, is short, frequently contorted, and densecovered with epiphytes including bromeliads, liverworts, and mosses-and includes only a few species of trees (Beard 1949, Wadsworth 1951, Howard 1968). The climate is wet, with nearly 5000 mm/yr of rainfall. Mean monthly temperatures range from 18 to 20?C (Weaver et al. 1973). The vegetation is commonly saturated with moisture and frequently enveloped in clouds. Both aerial and superficial roots are common (Lyford 1969). Saturated soils, impeded root respiration, physiological drought, high winds, high soil leaching, low nutrient availability, low temperatures, high fog incidence, reduced solar insolation, high humidity, reduced transpiration rates, and shallow soil have all been suggested as causal agents in stunting, either individually or in combination (Gleason & Cook 1927, Beard 1944, Wadsworth & Bonnet 1951, Holdridge 1967, Odum 1968, Baynton 1969, Grubb 1971, Weaver et al. 1973). Similar forests elsewhere in the Caribbean and Central America have been discussed by La Bastille and Pool (1978). Despite the abundance of hypotheses regarding the cause of dwarf cloud forests, little information is available on their growth rates, net primary productivity (NPP), and nutrient cyding. The purpose of this study is to determine species composition and standing biomass of the dwarf forest, and to estimate the rates of NPP, litterfall, and diameter and biomass growth of arborescent species. Rates of nutrient return to the soil are also in-

Fiddler Crab Regulation of Spartina alterniflora Production on a New England Salt Marsh

While a great deal of research has been directed at understanding the high productivity of marsh grasses, little attention has been paid to the potential importance of marsh fauna in influencing marsh grass production. The mud fiddler crab, Uca pugnax, excavates burrows in Spartina alterniflora—dominated salt marshes along the East Coast of North America. Here, I examined experimentally the effect of fiddler crab burrowing on S. alterniflora production. At low intertidal heights, S. alterniflora production was robust and characterized by tall—form plants with roots and rhizomes that penetrate deeply into the substrate. At higher tidal heights, low productivity, short—form S. alterniflora with a dense superficial root mat prevailed. Fiddler crabs differentially affected grass production at different tidal heights. In tall—form S. alterniflora stands at intermediate tidal heights, experimental reduction of fiddler crab density for a single growing season decreased aboveground production by 47% and increased root mat density by 35%. In contrast, on the lower intertidal soft edge of the marsh and in the high intertidal, dense root mat, short—form S. alterniflora zone, experimental reduction of crab density did not have as marked an effect on cordgrass production. Crab burrows were shown to increase soil drainage, soil oxidation—reduction potential, and in situ decompostion of belowground plant debris. The relationship between fiddler crabs and S. alterniflora appears to represent a faculatative mutualism. On the sewart edge of marshes in soft sediment that would not otherwise support burrow structures, the roots, rhizomes, and debris of S. alterniflora provide structural support and consequently facilitate burrowing. At intermediate tidal heights, intensive burrowing activity increases aboveground grass production and prevents the establishment of a dense root mat, while crabs are largely precluded from burrowing in the dense root mat, short—form S. alterniflora stands at higher tidal heights. Therefore, while initially dependent on S. alternifora in soft sediments, U. pugnax burrowing activity appears to maintain a habitat suitable for continued burrowing, and as a byproduct, increases cordgrass production and maintains tall—form S. alterniflora stands.

Growth dynamics of superficial roots in Portuguese plantations ofEucalyptus globulus Labill. studied with a mesh bag technique

The variation in growth of the fine roots of blue gum (Eucalyptus globulus labill. ssp.globulus) in the 0–40 cm soil layer was studied from March 1982 to March 1983 at Quinta do Furaduoro, Obidos, Portugal. A mesh bag method was used; bags of nylon net were inserted into a clay soil and a sandy soil and filled with root-free soil. They were resampled after 2, 4, 6 and 12 months in both places and, in a separate series in the sandy soil every second month throughout the year. The ingrowth of roots was high during the winter months but there was also a surprisingly high ingrowth during the spring-early summer period. There was also some root growth during the driest part of the yearviz. July–September. The amount of fine roots reached a maximum of about 260 g dw m−2 after about 6 months in the sandy soil, whereas it took at least 12 months to reach the somewhat higher level of 450 g dw m−2 in the clay soil. At that level the decomposition of dead roots was expected to equal the formation of new roots. Dead roots appeared after only 2 months. There was a higher proportion of dead roots in the clay soil than in the sandy soil, 35% as compared with 20% on an average, which indicates a slower decomposition or a higher mortality at equal decomposition rates in the clay than and in the sandy soil. The present data gives an indication of a minimum fine root production in mature Eucalyptus stands of at least 600 g dw m−2 yr−1.

Salsuginus Beverley-Burton, 1984 (Monogenea: Ancyrocephalidae) from Cyprinodontoidei (Atheriniformes) in North America with descriptions of Salsuginus angularis (Mueller, 1934) Beverley-Burton, 1984 from Fundulus diaphanus and Salsuginus heterocliti n. sp. from F. heteroclitus

Salsuginus Beverley-Burton, 1984 has been proposed for ancyrocephalid monogeneans found on North American Cyprinodontoidei (Atheriniformes). The genus is distinguished by the following characteristics: penis sclerotized, tubular, spiralling to form single coil; accessory piece with median groove to accommodate shaft of penis, distal point heavily sclerotized; dorsal and ventral hamuli similar in shape with distinct superficial and deep roots and curved blade; dorsal and ventral transverse bars bandlike, bowed posteriorly with posterior notch at extremities of each: larval hooks of similar shape and size with well-developed sickle bearing thumblike projection. Salsuginus angularis (Mueller, 1934) Beverley-Burton, 1984, the type species, is redescribed from the present material found on Fundulus diaphanus (Lesueur) in Ontario. Salsuginus umbraensis (Mizelle, 1938) n. comb., S. funudulus (Mizelle, 1940) Beverley-Burton. 1984. S. seculus (Mizelle and Arcadi, 1945) n. comb. and S. bahamianus (Hanek and Fernando, 1972) n. comb. are transferred from Urocleidus Mueller, 1934; S. spirae (Williams, 1980) n. comb. is transferred from Ancyrocephalus Creplin, 1839. Material found on F. heteroclitus taken in New Brunswick is described as S. heterocliti n. sp. Evolutionary aspects of Salsuginus spp. are briefly discussed and notes on the identification of species parasitizing Fundulus spp. are presented. Previous records of Salsuginus spp. are listed.

Intraalveolar transplantation of teeth with crown-root fractures

Intraalveolar transplantation using a simple extraction technique with extrusion of the root sufficiently to allow crown preparation was performed in 23 cases of crown-root fractures. A normal periodontal membrane was present after three months in all cases. Signs of superficial root resorption were observed in two cases, and small periapical radiolucencies were seen in another two, probably as a reaction to the presence of excess root-filling material. Minor remodeling of the marginal bone adjacent to the extruded roots was observed in eight cases.

A structural study of the interaction between the ectomycorrhizal fungus Pisolithus tinctorius and Pinus strobus roots

Stages in ectomycorrhizal development between the fungus Pisolithus tinctorius (Pers.) Coker & Couch and short roots of Pinus strobus L. were followed in growth pouches. Short roots from preinoculation through Hartig net formation were processed for light and electron microscopy. Fungal hyphae approaching the surface of roots have Thiéry-positive substances in their modified walls and in lomasomes, indicating the possibility of extracellular polysaccharide secretion. Hyphae grow between and beneath the flattened, tannin-filled superficial root cells and subsequently into the intercellular region of the cortex. A Hartig net several hyphae wide is formed, isolating the cortical cells from each other. Plasmodesmata were not observed in these cortical cells. Middle lamella material is always present around the intercellular hyphae, suggesting limited digestion by the hyphae. Cortical cell cytoplasm becomes necrotic in regions of mature Hartig net formation.

Growth rates, biomass and distribution of selected woody plant roots in Burkea africana-Ochna pulchra savanna

Woody plants in an African Burkea africana-Ochna pulchra savanna on deep sandy soil were found to have characteristically bimorphic root systems. The shallow lateral root component was often well developed and roots extended up to seven times the extent of the plant canopy in several species. Exponential tapering of lateral roots was found in Terminalia sericea. The wide-ranging roots, together with the high degree of multispecies root system interpenetration, result in the so-called, open grassy areas in the savanna mosaic often containing a competitively significant woody plant component. Root systems of Ochna pulchra were found to be relatively specialized and included: negatively geotropic, superficial roots; sinker roots to bedrock; high suckering response to damage in roots; belowground lignotuber-type organs; and sustained subterranean interconnections between some aboveground stems. These features are likely to contribute substantially to the resilience of this plant species to various climatic and veld management stress factors. Root/shoot mass ratios averaged unity but depended on plant size and aboveground growth form in Ochna pulchra. The dependence of these ratios on sizes of plant also applied to plant clones. Initiation of root tip growth occurred in early summer in one year and late spring in another. Main root tip growth occurred in late summer and early autumn, well after completion of most growth of leafy shoots in spring. It is suggested that some active uptake of water and nutrients by non-extending roots allows this form of phased growth in the plant. In an analysis of the seasonal growth of individual root tip systems, it was clear that transitory states of rest occur in fine root development but that these are far more frequent in the branching (and hence proliferation) of roots than in the continuing development of any root axis.

Death of Tea in Malawi Caused byPseudophaeolus baudonii

Abstract Damage to tea plants due to a root infection was observed on an estate in southern Malawi. Initial symptoms on plants in the infected areas varied from yellowing of leaves on individual branches followed by dieback to a more frequent rapid wilting of the leaves of entire bushes. The bark surface of superficial roots and collar region was covered by a loose mat of coarse fungal mycelium varying from white or cream to pale or bright yellow in colour. Infection was well developed on a large proportion of roots of affected plants before foliage symptoms appeared. The causal agent was identified as Pseudophaeolus baudonii (Pat.) Ryv.; this is the first record of the fungus in Malawi and the first record of its occurrence anywhere on tea. The fungus is widely distributed in Africa on a range of hosts. It is not yet known how the fungus is transmitted and definite control methods cannot be recommended although it is suggested that entire tea crops in diseased areas be removed and the land used for tobacco production. It is unlikely thatP. baudonii will have serious economic effects on tea crops in the area.