Abundant Plant Material Research Articles

New sources of resistance to Phytophthora megakarya identified in wild cocoa tree populations of French Guiana

Cocoa black pod rot, a disease caused by oomycetes of the genus Phytophthora, causes substantial yield losses throughout the world, particularly in Africa with the very aggressive species Phytophthora megakarya. In order to reduce the impact of that pathogen, priority is given to genetic control through more resistant cultivars, and breeders are seeking sources of resistance in wild cocoa trees. Wild cocoa trees were surveyed in French Guiana between 1985 and 1995, leading to the collection of abundant plant material from more than 200 mother trees originating from five river basins. We present here the results of tests to assess resistance to the species P. megakarya (a species only existing in Africa), conducted at CIRAD in Montpellier, France, on circa 40 genotypes collected in the Camopi river basin, along with approximately 20 genotypes from other populations (Kérindioutou, Borne 7, Euleupousing, Pina and Oyapok). The strain used for artificial inoculation was NS269, isolated in Cameroon. Seven cacao clones were classified as “highly resistant” and 29 as “resistant”, some of which displayed greater resistance to P. megakarya than the reference resistant clone IMC 47. This study suggests that the wild material from French Guiana could play a significant role in controlling P. megakarya in Africa and also Phytophthora palmivora in all cocoa-producing zones.

Karst-related outliers of the Cretaceous Chaswood Formation of Maritime Canada

The Lower Cretaceous Chaswood Formation is a terrestrial deposit preserved as scattered outcrops across Maritime Canada. Here we describe newly recognized outliers of the Chaswood Formation near Windsor, Nova Scotia. A Cretaceous age is confirmed only in Bailey Quarry, where sediments are provisionally assigned a Valanginian–Hauterivian (140–130 Ma) age based on palynology, making them among the oldest known deposits of the Chaswood Formation. At three nearby sites, putative Cretaceous sediments are recognized based on similar geological context, facies, and petrography; however, their age cannot be confirmed because sediments either lack palynomorphs or contain equivocal assemblages. Although the Chaswood Formation has been previously documented mainly in small tectonically generated basins, these new-found deposits are fluvial sands and gravels, and lacustrine or floodplain clays associated with a karstified gypsum surface developed on the Carboniferous Windsor Group. Deposits are preserved in karst valleys, sinkholes, and fissures, locally up to 36 m below the paleosurface. Although occupying a karstic setting, sediments were evidently deposited in a through-flowing drainage system because they are quartz-rich and show petrographic similarity to basinal deposits elsewhere. Abundant plant material, including lignite, charcoal, cuticles, and palynomorphs, implies that the surrounding landscape was covered by fire-prone forests of conifers, ginkgos, bennettites, cycads, ferns, and lycopods — typical pre-angiosperm Mesozoic vegetation. Analysis of growth patterns in fossil woods, combined with lithological indicators, suggest a humid, tropical climate, punctuated by aperiodic droughts that may have been accentuated under a karstic hydrological regime.

Ichnology of Lower Jurassic beach deposits in the Shemshak Formation at Shahmirzad, southeastern Alborz Mountains, Iran

A 19 m thick package of well-sorted lowermost Jurassic (Hettangian-Lower Sinemurian?) sandstones within the Shemshak Formation of the southeastern Alborz Mountains displays features characteristic of foreshore to upper shoreface environments such as tabular bedding, low-angle lamination, trough cross-stratification, parting lineation, and oscillation ripples. In contrast to most other beach successions recorded in the literature the sandstones contain a trace fossil assemblage characterised by low abundance but comparatively high diversity. The assemblage, comprising 14 ichnotaxa, is dominated by Palaeophycus heberti, Rhizocorallium irregulare, Gyrochorte comosa, and Parahaentzschelinia surlyki. Contrary to predictions, which assume a dominance of suspension-feeders in such high-energy environments, the trace fossil assemblage represents a variety of ethological groups ranging from suspension-feeders to deposit-feeders, detritus-feeders, scavengers, and a possible trap constructor (Ctenopholeus), whereby deposit-feeders predominate. This anomaly is explained by a high amount of organic detritus in the sediment, indicated by abundant plant material, and a position of the beach in the vicinity of a river mouth.

Influence of water stress on spring barley yields under Polish climatic conditions

The aim of this study was to evaluate the influence of atmospheric precipitation on the yield of spring malting barley. The plant height and heading of the studied forms were observed as additional indicators of their reaction to variable water conditions. The plant material for this study consisted of spring barley breeding lines in generations F6-F7 evaluated at 7 locations in 1996-2001. The highest yield was observed with precipitation within the range 258-321 or 356-382 mm per growing season in years with colder or warm weather, respectively. These results were obtained using abundant plant material highly differentiated genetically, so it may be inferred that the above values are the rainfall levels optimal for spring barley cultivation under Polish climatic conditions. The experimental locations could be divided into four classes according to observations on mean yields and on total rainfall before heading and between heading and full maturity. the optimal class included locations where the highest yield was observed; in the second there was a high precipitation level but a lower yield was obtained; in the third class there was a shortage of rainfall before heading, and in the fourth class there was a shortage of rainfall between heading and maturity. The observation of yields lower than those obtained in optimal locations led to the assumption that stress factors at these locations did not allow the yield potential of the studied genotypes to be fully expressed. The studied genotypes showed good adaptation to the variable conditions of the Polish climate, which is characterized by periods with a shortage or excess of rainfall.

IN VITRO AND EX VITRO ROOTING AND PLANTLET ACCLIMATIZATION IN NERIUM OLEANDER

Oleander (Nerium oleander L.) is cultivated recently as a flowering pot plant and therefore abundant propagation plant material for commercial use is of great importance. In this study an effort was undertaken to investigate microcutting rooting in vitro and ex vitro and also acclimatization of young microplants. A single white flower clone of oleander was used for the experiments. Microshoots derived from in vitro stock cultures were used as microcuttings and placed for rooting in vitro or ex vitro. For in vitro rooting, the microcuttings were placed in WPM supplemented with IAA or NAA in various concentrations (0, 0.5, 1 or 2 pM). The best rooting was achieved with 2 pM NAA (23%). For ex vitro rooting, the microcuttings were first dipped in various concentrations (0, 0.13, 0.25 or 0.5 g l -1 ) of K-IBA and then were planted in perlite and kept in a fog system with relative humidity adjusted to 96-99%. Rooting was up to 70% with 0.5 g l -1 K-IBA. After rooting in vitro or ex vitro, the young plantlets were transplanted in pots and placed for hardening in a fog system with initial relative humidity at 95%, which then was decreased gradually to 80% in two weeks. The plantlets in the fog system were either under direct sunlight or under 50% shading provided by a net which lasted for 1 week and was removed afterwards. The transplanting losses for those rooted in vitro for both treatments were less than 5%, whereas no losses were noticed in those plantlets derived from ex vitro rooting.

Lacustrine to fluvial floodplain deposition in the Eocene Bridger Formation

The depositional systems and sedimentology of lithofacies sequences in the Bridger Formation (unit B) are described. A lithofacies association is determined and includes from base to top: limestone, claystone, thin bedded sandstone and siltstone, and a cross-bedded sandstone facies. The limestone facies is generally composed of a dense resistant limestone that may contain fossil plant impressions, tufa and/or stromatolites, gastropods, bivalves, and other fossils. The claystone facies contains abundant fossil turtles, gar, crocodiles, gastropods and plants. Desiccation cracks, plant roots and soil features are lacking. Extremely abundant turtles may occur in this facies, sometimes associated with abundant coalified plant fragments. The thin bedded sandstone and siltstone facies is composed of silty clay to medium sand. At a few localities it grades laterally into medium- to course-grained sandstone channels up to 3 m thick. Fossil turtles are present, but are much less abundant than in the claystone facies. The cross-bedded sandstone facies is composed of thick, laterally extensive channel sandstones associated laterally with silty claystone beds. The lithofacies association is interpreted as a shallowing upward sequence. It started with a basal limestone facies, deposited in a widespread, shallow, carbonate-precipitating lake. The lake was rapidly filled by episodic volcaniclastic deposition, delivered via air-fall and/or prograding fluvial–deltaic systems. Deltaic deposition may have been similar to the infilling of the northern portion of Lake Turkana in Africa by the Omo River Delta. The claystone facies is interpreted as a short-lived fluvial–lacustrine system that prograded out over the limestone facies and/or was deposited as air-fall ash into the entire lake. The sharp upper contact of the limestone facies with the claystone facies suggests that an abrupt paleoenvironmental change may have taken place with a large influx of volcaniclastics. An organic-rich unit, the organic turtle bed within the Black Mountain turtle layer (a claystone facies), contains abundant plant material and turtles and is interpreted as representing an episodic depositional event, probably storm related. As volcaniclastic deposition continued to dominate the system, the thin bedded sandstone and siltstone facies sequence was deposited. It is interpreted as distributary and crevasse splay sheet sands uniformly deposited (laterally correlative) over large areas. This depositional system was ultimately replaced by a well-established, fluvial floodplain environment with large fluvial channels representing major meandering rivers. Development of the succeeding lake system occurred when siliciclastic deposition significantly slowed relative to the rate of basin subsidence. Deposition in the Bridger Formation, unit B, suggests a delicate balance between a closely interacting lacustrine and fluvial system. Although fluvial processes and clastic sedimentation dominated depositional patterns, lacustrine depositional regimes frequently returned.

The Late Pleistocene - Holocene palaeolimnology of Lake Victoria East Africa, based upon elemental and isotopic analyses of sedimentary organic matter

Three piston cores from Lake Victoria (East Africa) have been analysed for organic carbon (TOC) and nitrogen (TN) content, stable isotopes (δ13C and δ15N), and Hydrogen Index (HI). These data are combined with published biogenic silica and water content analyses to produce a detailed palaeolimnological history of the lake over the past ca. 17.5 ka. Late Pleistocene desiccation produced a lake-wide discontinuity marked by a vertisol. Sediments below the discontinuity are characterised by relatively low TOC and HI values, and high C/N, δ13C and δ15N, reflecting the combined influence of abundant terrestrial plant material and generally unfavourable conditions for organic matter preservation. A thin muddy interval with lower δ13C and higher HI and water content indicates that dry conditions were interrupted by a humid period of a few hundred years duration when the lake was at least 35 m deep. The climate changed to significantly more humid conditions around 15.2 ka when the dry lake floor was rapidly flooded. Abundant macrophytic plant debris and high TOC and δ13C values at the upper vertisol surface probably reflect a marginal swamp. δ13C values decrease abruptly and HI begins to increase around 15 ka BP, marking a shift to deeper-water conditions and algal-dominated lake production. C/N values are relatively low during this period, suggesting a generally adequate supply of nitrogen, but increasing δ15N values reflect intense utilisation of the lake's DIN reservoir, probably due to a dramatic rise in productivity as nutrients were released to the lake from the flooded land surface. An abrupt drop in δ13C and δ15N values around 13.8-13.6 ka reflects a period of deep mixing. Productivity increased due to more efficient nutrient recycling, and δ13C values fell as 12C-rich CO2 released by bacterial decomposition of the organic material was brought into the epilimnion. A weak drop in HI values suggests greater oxygen supply to the hypolimnion at this time. Better mixing was probably due to increased wind intensity and may mark the onset of the Younger Dryas in the region. After the period of deep mixing, the water column became more stable. TOC, C/N, δ13C and HI values were at a maximum during the period between 10 and 4 ka, when the lake probably had a stratified water column with anoxic bottom waters. A gradual decrease in values over the last 4000 yrs suggest a change to a more seasonal climate, with periodic mixing of the water column. Rising sediment accumulation rates and a trend to more uniform surface water conditions over the last 2000 yrs are probably a result of increased anthropogenic impact on the lake and its catchment. Following a maximum at the time of the rapid lake-level rise during the terminal Pleistocene, δ15N has remained relatively low and displays a gradual but consistent trend to lower values from the end of the Pleistocene to the present. TN values have risen during the same period. The lack of correlation between δ13C and δ15N, and the absence of any evidence for isotopic reservoir effects despite the rise in TN, suggests that the atmosphere, rather than the lake's dissolved nitrogen pool has been the principal source of nitrogen throughout the Holocene. The importance of atmospheric N fixation to Lake Victoria's nitrogen cycle thus predates by a very considerable margin any possible anthropogenic eutrophication of the lake.

Diet and feeding relationships of two Iberian cyprinids

The diet and feeding interactions of the Iberian roach, Rutilus alburnoides (Steindachner), and chub, Leuciscus pyrenaicus Günther, were studied in the Sorraia river system. Seasonal shifts in the diets were examined to determine trophic overlap between the two species. Dipteran larvae were the dominant item in the diet of roach with the exception of summer and early autumn when dipteran adults became important. Ephemeroptera nymphs and imagos were the two principal food categories in chub diet. Plant material and terrestrial insects were consumed by both species mostly in the summer and autumn, periods of low availability of aquatic invertebrates in temperate streams. A low dietary overlap was found, probably resulting from differences in their seasonal foraging activity, but also from a compromise between the consumption of highly abundant plant material and rare animal food items.

Depositional facies and environments in the Permian Umm Irna formation, Dead Sea area, Jordan

The Permian Umm Irna Formation in central Jordan consists of a 60 m thick sequence of clastic sediments which can be divided into two fluvial sedimentary facies. The lowermost facies (1) is characterized by the presence of five sandstone-dominated fining-upward sequences, each sequence comprising an erosively based coarse- to fine-grained, trough cross-bedded sandstone, overlain and laterally intertonguing with maroon siltstone and silty-shale, containing locally abundant carbonaceous plant material. The overlying facies (2) also consists of up to five fining-upward sequences, each comprising an erosively based coarse-grained pebbly sandstone grading up through fine-grained sandstone and siltstone into silty-shale. The sandstones are tabular, and laterally persistent, internally complex units structured by erosively bounded trough cosets. The thickness and grain size of the sandstones and the proportion of siltstone and silty-shale is much greater than in facies (1); it also contains abundant ferruginous concretions (glaebules). Deposition occurred on an unconfined braidplain sloping northwestwards away from an elevated provenance (Arabo-Nubian Shield) in the south and east. The lowermost facies (1) is regarded as a distal environmental equivalent of the overlying facies (2). Deposition was largely controlled by period c shifts of the active channel tract, influenced by a gradual increase in the elevation of the source area, thereby promoting basinwide progradation and vertical stacking of the two major facies components. The ferruginous concretions (glaebules) in facies (2) are thought to have resulted from diagenetic processes in the vadose zone of a humid, possibly tropical climate, characterized by alternating wet and dry seasons and strong leaching. The fluvial depositional system drained basinwards into a shallow-water marine depository along the southern margin of the Tethys Ocean. The ocean may have exerted a maritime influence on the climate of the alluvial plain.

Early history of the Arctic Ocean

The Lomonosov Ridge divides the Arctic Ocean into two basins with different histories. The older Amerasian Basin consists of a ridge‐basin complex reflecting multiple tectonic cycles that are poorly understood. The younger Eurasian Basin includes the present Arctic Mid‐Ocean Ridge. Its origin is linked to Cenozoic spreading. The entire older sediment record of the Arctic Ocean is known from only four short piston cores, all recovered from the Alpha Ridge of the Amerasian Basin. The oldest sediment recovered is a single core of black mud consisting of abundant terrestrial plant material deposited in a marine environment. Dinoflagellates are late Campanian. The black mud resulted from rapid accumulation of organic matter rather than from any of the well‐known Cretaceous anoxic events. Two cores taken 100 to 200 km from the black mud consist of late Maastrichtian siliceous ooze of diatoms and silicoflagellates. This sediment has been interpreted to represent oceanic upwelling and high productivity in the Late Cretaceous Arctic Ocean. A Paleogene core consisting of similar biogenic silica has been recovered approximately 100 km from the Cretaceous cores. Silicoflagellates of this core are either Paleocene or middle to late Eocene. The sediment, like that of the Maastrichtian cores, has been interpreted to represent oceanic upwelling and high productivity. The older Arctic cores were recovered as a result of fortuitous sampling in areas of thin late Cenozoic sediment. All other Arctic cores consist of late Cenozoic sediment. The older sediment record is strong evidence of a Late Cretaceous to early Paleogene Arctic Ocean with no perennial ice and with high productivity of dinoflagellates or siliceous organisms in water that circulated with lower‐latitude oceans. Recent modeling predicts some of the same climatic and oceanographic events recognized in the oldest sediment of the Arctic Ocean. The sequence of events from a warm Arctic Ocean to an ice‐covered condition involved circulation changes, seasonality, and uneven spreading rates that increased North Atlantic‐Arctic ventilation.

Diet of the Australian grayling, Prototroctes maraena Gnnther (Salmoniformes : Prototroctidae), with notes on the occurence of a trematode parasite and black peritoneum

The diet of the Australian grayling was studied based upon an examination of the stomach and intestinal contents of 558 fish taken from the Tambo River, Victoria, throughout 1979. The most frequent food items were the immature stages of aquatic insects such as chironomids, trichopterans, and ephemeropterans, gastropods and abundant plant material in the form of a diatom/organic matrix that occurred in 83% of the stomachs. It is speculated that the grayling's black peritoneum is related to the presence of plant matter in the diet. A total of 120 different taxa was recorded but only 23 taxa occurred in 5% or more of the stomachs. Most stomachs were three-quarters full and mean monthly fullness varied little throughout the year. There was little dietary overlap between summer (when the diatom/organic matrix was of relatively low importance) and the other seasons in all size classes examined. There was significant dietary overlap between the size groups for all seasons except summer. Trematode parsites of the family Opecoelidae occurred throughout the gut in 86% of the specimens. The largest fish had the most parasites, and the incidence of infection was consistently high throughout the year.

Origin of varve-type lamination, graded claystones and limestone-shale ‘couplets’ in the lower Cretaceous of the western North Atlantic

Summary The petrography and sedimentary structures of pelagic and hemipelagic sediments in the early Cretaceous interval of the Blake-Bahama Basin reveal a subtle interplay between terrigenous source materials, plankton productivity and diagenesis. Three specific sediment types drilled at Site 534A (Leg 76) of the DSDP are: (1) persistent, fine parallel lamination resembling varves; (2) thin, size-graded nannofossil claystones and ‘black shales’, and (3) ‘couplets’, composed of pale burrowed and dark laminated nannofossil radiolarian carbonates. The varve-type lamination reflects some combination of fluctuations of terrigenous plant material plus fine clastic input and plankton productivity. Both possibly reflect short periodicity (10s to 100s of years) climatic variations. Lithification took longer in the clay-and organic-rich laminae. Slow compaction then accentuated the lamination. By contrast, purer nannofossil oozes lithified more quickly and now show less compaction. The graded claystones and ‘black shales’ were mostly redeposited by turbidites from within, or near, the oxygen-minimum zone on the upper continental slope. Turbiditic input reduces the need for bottom water anoxicity. The dark-light couplets reflect wetter periods on land averaging 20–60 000 years, during which abundant plant material entered the Atlantic. Contrary to some recent suggestions, the early Cretaceous Atlantic need not have been poorly circulated and weakly oxygenated. Instead, both short and longer periodicity climatic fluctuations controlled input of mostly land-derived material. High rates of organic matter input, partly turbiditic, produced sub-surface sediment anoxia below a circulating relatively fertile early Cretaceous Atlantic Ocean.

Depositional Environment of Dry Hollow Member, Upper Cretaceous Frontier Formation, Southwestern Wyoming: ABSTRACT

The Dry Hollow Member of the Frontier Formation in southwestern Wyoming consists of alluvial deposits that accumulated along part of the western margin of the Western Interior Cretaceous seaway. Typically, the lower part of the Dry Hollow Member contains sandstone bodies 4 to 15 m thick that fine upward and possess basal conglomeratic lenses. These units are interpreted as channel deposits of meandering streams, with the conglomerates having formed as channel-lag deposits. Commonly, silicified wood, plant fragments, freshwater gastropods, and intraformational shale clasts are present in these deposits. Medium-scale trough cross-stratification is dominant and indicates a general west to east paleocurrent direction. The upper part of the Dry Hollow Member is dominated by interbedded shales, coals, and thin (0.2 to 1 m) fine-grained sandstones. The shales contain abundant carbonaceous plant material, silicified wood, and lignitic layers. Root horizons are commonly preserved within large (0.3 to 1 m) concretions that formed in the shales. The interbedded fine-grained sandstones are typically small-scale trough cross-stratified and contain abundant plant material. These sandstones are interpreted as near-channel overbank deposits that accumulated during periods of stream flooding, while the shales and coals represent vertical accretion deposits of interchannel swamps and lowlands that accumulated farther from the stream channels. Analysis of these deposits suggests that a wet, poorly-drained fluvial lowland dominated by meandering streams and coal swamps existed along the Western Interior Cretaceous seaway during deposition of the bulk of the Dry Hollow Member of the Frontier Formation. End_of_Article - Last_Page 987------------

Origin of San Miguel Lignite Deposit and Associated Lithofacies, Jackson Group, South Texas

The stratigraphy and depositional environment of the San Miguel lignite deposit, southeastern Atascosa and northern McMullen Counties, Texas, were determined from the analysis of 3 continuous cores and 600 borehole logs. Five units can be recognized by their characteristic composition, texture, sedimentary structures, paleontology, and morphology. Lithofacies 1 is a light-green to gray, cross-laminated sandstone and conglomerate unit. The grain size decreases upward in the bedsets and the unit contains abundant plant and carbonaceous material. These characteristics indicate a fluvial origin. Lithofacies 2, a gray-green bioturbated siltstone and claystone unit, has abundant root structures and was deposited in a coastal grassflats environment. Lithofacies 3 was deposited i a lagoonal environment. It is a green, massive claystone with numerous fossiliferous and marly beds. The fossil mollusks have modern counterparts which flourish in open bays or lagoons. Lithofacies 4 is a coarse, carbonaceous sandstone. Deposition in a barrier-flat environment is indicated by the sequence of roots and bioturbation structures overlying a massively bedded zone. The lignite interval is an alternating sequence of lignite and clay partings. The lignite represents accumulation of plant debris and peat development in a coastal marsh adjacent to a lagoon. The clay partings formed through repeated floodings of the marsh by coastal streams. This marsh was part of the south Texas Jackson Group lagoonal-coastal plain system, an updip equivalent of the south Texas strandplain-barrie bar system. The mining of lignite can be made more efficient by determining the stratigraphy and depositional environment of the lignite and associated units. Analysis of cores and borehole logs makes it possible to predict that the San Miguel lignite will have (1) high sulfur and ash content; (2) low Btu and fixed carbon values; (3) lateral continuity; and (4) relatively constant thickness.

Age of Arkose Ridge Formation, South-Central Alaska: GEOLOGICAL NOTES

The Arkose Ridge Formation of the southwestern Talkeetna Mountains adjacent to the lower Matanuska Valley, has been a stratigraphic enigma. The formation consists of arkose, shale, sandstone, and conglomerate, contains abundant plant material, and may be more than 6000 ft. thick. The fossil plants were first thought to be of Eocene Age; new collections indicate an Albian or possibly a Cenomanian Age for the formation. This age determination suggests that the Arkose Ridge Formation is correlative with mollusk-dated marine beds in the lower part of the Matanuska Formation; these marine strata vary throughout the region from a thin section of glauconitic calcareous sandstone, silty claystone, and algal limestone, to thin sections of feldspathic sandstone and siltstone.

Cordaitean Wood from the Pennsylvanian of Michigan and Ohio

(WITH TEN FIGURES) Among the petrified wood specimens in the Museum of Paleontology of the University of Michigan, two unstudied samples from Michigan and Ohio were recently found. The Michigan specimen was collected by a museum party from a quarry along the south bank of the Grand River, about one mile west of Grand Ledge, in I925.' In the same quarry is a vein of coal a foot or more thick, and a few feet above is a massive sandstone layer bearing Calamites and Artisia casts. Immediately below the coal is a layer of Stigmaria shale, and below this and also between the coal and the upper sandstone are shales bearing numerous impressions of foliage, stems, and seeds of common Paleozoic plants. The source of the Ohio specimen is unknown, except that the label reads Coshocton, The specimen appears to have been in the collection for many years, possibly having been obtained by CARL ROMINGER. But few American Paleozoic woods are known as compared with woods of similar age from other parts of the world. Among those described within recent years, probably the most outstanding are Calamopitys americana and Archeopitys eastmanii, from the base of the Waverley Shale of Boyle County, Kentucky (I3). HoSKINS (5) and REED (i i) have recently reported abundant petrified plant material in the Pennsylvanian coal balls of Illinois, which, when more fully investigated, are likely to make notable additions. Probably the most widespread and abundant American Paleozoic wood is Callixylon. C. newberryi has long been known from the black shales of Ohio. In I9I4, ELKINS and WIELAND (4) described C. oweni from the black shales of Indiana, and in I922 HYLANDER (6)