Broad-leaved Plants Research Articles

Selective plant growth suppression by shoot application of soil bacteria

Selected rhizosphere bacterial isolates, previously determined as plant growth deleterious, were tested for their ability to suppress plant growth after foliar spray applications, for selectivity with regard to plant species, and in pilot field experiments for their potential as weed biocontrol agents. Inundative foliar applications of aqueous bacterial suspension were performed on a range of weed and crop species. Plant symptoms after spraying ranged from rapid necrosis and wilting to an overall growth suppression or stunting. Significant and selective reductions in biomass of up to 90% fresh weight, as well as large reductions in plant survival and plant height were recorded in greenhouse pot experiments. However, monocotyledonous plants were affected weakly or not at all by two isolates extensively tested. Effects of these were dose- and plant age-dependent, and were for some plants enhanced by high relative humidity. For one isolate, A153, effects were also expressed in cell-free culture filtrates pointing to involvement of specific metabolites. In pilot field experiments, strong growth suppression was observed on broad-leaved plants, while barley crop plants were unaffected.

Field guide to the broad-leaved herbaceous plants of south Texas: used by livestock and wildlife

Field guide to the broad-leaved herbaceous plants of south Texas: used by livestock and wildlife

FOSSIL LEAVES AS BIOSENSORS OF EOCENE PALEOATMOSPHERIC CO2

During the Cretaceous, as broad-leaved flowering plants evolved leaf forms similar to those seen in many flowering plants today, they had to develop physiological responses to changes in the supply of basic resources such as [CO2]. As the amount of [CO2] varied, the anatomy of the leaves accommodated these fluctuations, displaying physiologically determined signals that can be used to discriminate atmospheric levels of [CO2]. A decreasing number of stomata (air exchange holes in a leaf) on leaves of broad-leaved trees, as determined by stomatal index, indicates an increase in [CO2]. The stomatal index represents the ratio of the number of stomata per unit leaf area to the number of total epidermal cells per unit leaf area, thus expressing frequency independently of variation in epidermal cell size, serving as a sensitive parameter for detecting stomatal frequency changes. In comparing the stomatal indexes of leaves of the loblolly bay (Gordonia lasianthus) with those of 100-year-old leaves and of related Eocene leaves, significant differences were observed between these groups which appear to be directly related to the atmospheric [CO2] present when the leaves grew. Our preliminary results indicate that the Eocene p[CO2] was the order of 450–500 ppmv at a time when the earth was significantly warmer than today. Analysis of stomatal indexes over time provides a useful method for quantifying past environmental changes of [CO2].

Relationships between cellular injury, visible injury of leaves, and ozone exposure levels for several dicotyledonous plant species at Great Smoky Mountains National Park

Ozone is a ubiquitous air pollutant in the troposphere that can significantly affect terrestrial vegetation. Great Smoky Mountains National Park (GRSM), in eastern Tennessee and in western North Carolina, is experiencing ozone concentrations that may be sufficient to injure vegetation. The purpose of this research was to determine (1) if the percentages of dead palisade parenchyma cells were correlated with the percentages of leaf area that exhibited stippling (necrosis) and (2) if percentages of dead palisade parenchyma cells were correlated with cumulative ozone exposure for leaves of native plants in field chamber ozone exposures at GRSM. Such relationships between cells and leaf injuries with cumulative ozone exposure level may eventually provide an understanding of the leaf anatomical parameters that confer sensitivity of foliage to ozone insult. Using linear regression models, percentages of dead palisade parenchyma cells were correlated positively with percentages of leaf areas with visible injuries for Sassafras albidum, Rudbeckia laciniata, and Rubus canadenis for two growing seasons. For each of the three species there were positive relationships with r 2 values between 0.52 and 0.90 with probability values below 0.001 in all cases. No statistically significant relationships for these parameters occurred for Aster divaricatus, Magnolia tripetela, Liquidamber styraciflua, Rhus copallina, and Platanus occidentalis. The lack of relationships for these five species between percentage of dead cells and percentage of leaf area with visible leaf injury was attributed to large percentages of palisade cell death with only small amounts of visible leaf injuries during fumigation. In addition to the above relationships, percentages of dead palisade parenchyma cells were positively correlated by linear regression with cumulative ozone exposure for S. albidum ( r 2=0.83) and R. canadensis ( r 2=0.64). Both had probability values below 0.001. The results are discussed with regard to the factors that may confer such levels of sensitivity which need to be tested quantitatively. To our knowledge this is the first report to demonstrate statistically significant quantitative relationships among percentage of dead palisade parenchyma cells, percentage of leaf area with visible injuries, and cumulative ozone exposure of foliage of broad-leaved plant species.

Reproductive Behavior of the Specialist Predator Elatophilus hebraicus (Hemiptera: Anthocoridae)

The reproductive biology of Elatophilus hebraicus Pericart, the principal predator of Matsucoccus josephi Bodenheimer & Harpaz (Homoptera: Matsucoccidae), was investigated. Oviposition is usually through a stoma. Eggs were laid on both adaxial and abaxial sides along the needle. In the forest usually a few eggs were inserted in a straight line through the adaxial side; additional eggs were observed in needles collected from the north-facing, inner parts of the crown. Females of E. hebraicus were exposed separately to 28 plant species. Adult needles of each of the 17 pine species employed, which consisted of both Haloxylon and Dilpoxylon, served for oviposition and successful neonate hatching. No oviposition took place in juvenile needles of tested pines. Oviposition did not occur in conifer needles other than pine or in needlelike assimilating organs of broad-leaved plants. A possible explanation of the ability of E. hebraicus to recognize pines and reject other plants is discussed. The preoviposition period ranged from 3.8 to 5.1 d. Significant differences were found in length of oviposition periods and life span under different temperature regimes. The highest mean number of eggs per female (202.7) was achieved when development and oviposition occurred at 26°C. At constant 20°C, or 18-28°C outdoors, an average female lived ≈3 mo; oviposition lasted ≈2 mo; and a female's life span was reduced to 5 and 2 wk at constant 26 and 30°C, respectively.

Variation in fluoride content and leaf injury on plants associated with three aluminium smelters in Norway

Fluoride content and leaf injury were recorded in different plant species and genotypes associated with aluminium smelters in northern, continental and maritime parts of Norway. Generally, all deciduous broad-leaved plants were low in fluorides in the spring. The leaf F content increased during the growing season. The F accumulation rate (K) varied with species and exposure conditions. It was highest in Sorbus aucuparia, thus giving a 2–3-fold higher F content in this foliage than in Pinus sylvestris. Also, the within-species variation was great, 20–40%. Plant species and genotypes exhibited a broad range of tolerance to foliar injury. Leaf injury also varied with exposure conditions. Pinus sylvestris was most sensitive, showing clear leaf injury symptoms already at a F content below 50 p.p.m., at the northernmost locality and below 100 p.p.m. under southern maritime conditions. Broad-leaved spontaneous species like Betula pubescens, Salix caprea and Sorbus aucuparia showed similar symptoms at about 100 and 170 p.p.m., respectively. Also plants grown at the generally poorer climatic conditions at high altitudes had lower critical load for leaf injury than the same species grown at lower altitudes. Evaluation of sampling procedure showed that the phenological stage of the plants or sampling time, leaf age — i.e. basal and terminal leaves - and exposure on the tree — luff or lee side — strongly effected the measured fluoride content in the leaves. In comparative studies those conditions have to be taken into consideration. According to the present results, Sorbus aucuparia seem to be the best species for monitoring of antropogenic fluoride by leaf analyses under Norwegian conditions.

Botanical composition and models of metabolizable energy availability from undergrowth in oil palm plantations for ruminant production

The availability of undergrowth is essential for integrating ruminant animals into oil palm plantations. This is because undergrowth can be used as a feed resource for ruminants. This type of production system has the advantage of diversifying income and controlling weeds in the plantation. At least fve botanical groups of herbage can be found in oil palm plantations, namely, grasses, broad leaved plants, legumes, ferns and palms. Grasses were found in abundant through all palm ages. Most grasses are tolerant to higher light intensity and some are shade-tolerant. This study showed that in the early stages of oil palm crop development, sun-loving species tend to dominate the field, mostly broad leaves and legumes, but they will gradually be replaced by shade-tolerant plants when the canopies close. Concentration of metabolizable energy in herbage on offer was 4.6 to 7.0 MJ/kg dry matter. Crude protein content of grasses, broad leaves, legumes, ferns and palms are 11.5%, 15.4%, 16.3%, 12.5% and 12.0%, respectively. Ruminant animals preferred broad leaved plants more than other botanical groups found in oil palm plantation. This paper showed that metabolizable energy available (MEA) models can be used for predicting available energy (MJ/ha/day) from the system for grazing ruminants. This is because MEA model was developed based on both quality and quantity of herbage present in the ecosystem.

Late Maastrichtian and Danian Ostracode Faunas from Northern Alaska: Reconstructions of Environment and Paleogeography

A 300-m sequence of well-exposed fossiliferous outcrops in bluffs along the Colville River, northern Alaska, has yielded diverse, well-preserved Maastrichtian and Danian ostracode assemblages. High-latitude faunas of this age are uncommon, so that this locality provides a unique opportunity to reconstruct an ancient arctic environment. The Maastrichtian strata are nonmarine flood-plain deposits and contain diverse terrestrial and aquatic fossils. The paleoenvironment was a broad, flat, water-saturated delta plain with a diverse herbaceous ground cover, emergent and subaquatic vegetation, and a dry ground upland microthermal forest of deciduous coniferous and broad-leaved plants

Tent Roosts of Macconnell's Bat (Vampyressa macconnelli)

Between 11 September and 2 November 1990, 26 tent roosts, four of which were occupied by Macconnell's bat (Vampyressa macconnelli), were discovered in an area of mature flood plain forest in Manu National Park, Madre de Dios, Peru. All were constructed in the terminal blade of unseparated pinnae in fronds of Astrocaryum macrocalyx Burret (Palmae). Tents generally were not found in fronds of A. macrocalyx shorter than 2 m or longer than 4 m, or in other species of palms or broad-leaved plants that have been reported to harbor tent roosts of bats. The proximal four to nine unseparated pinnae of the terminal blade were severed to form the tent. Tents averaged 50.7 cm long, 17.1 cm maximum width, and 16.7 cm maximum depth, and were an average of 2.33 m above the ground. From one to seven bats were present in the four occupied tents but were not present in a tent every day. The density of active tents was ca 0.74/ha.

Microscopy studies of flower structures

The flowers of broad-leaved plants have four floral structures which differ significantly in shape from flower to flower. The sepals, petals, stigmas and pistils all have characteristic shapes and examples of all of them have been studied with scanning electron microscopy (SEM). The petals appear to be the most delicate of these structures and are therefore useful as indicators for senescence, as indicators for pollution effects or for developmental characteristics. Petals of most flowers are stamens which have switched roles during evolution from sexual organ to agents which attract pollinators. Even though they appear to be smooth to the unaided eye, they have fine sculptured detail when observed with SEM. Adaxial surfaces of some petals have closely packed cells which project from the surface and often have fine ridges or points. The reason for this is unknown, but is likely related to the reflection of light from petals.

Effect of Substrate Architecture on Aquatic Gastropod-Substrate Associations

In a laboratory experiment, we tested how substrate shape influenced snail-substrate associations by measuring colonization by one large species (Lymnaea stagnalis) and one small species (Amnicola sp.) on five substrates (presented separately) constructed of balsa wood, coated with dried creamed spinach. All five substrates (a prostrate square, standing inverted triangle, standing rectangle, standing 1 cm wide strips, and standing 1 mm wide strips) had equal surface area, but differed in shape and degree of contact with the bottom. Substrates were designed to mimic natural substrates (e.g., 1 mm strips mimic dissected macrophyte leaf morphologies, prostrate square mimics prostrate growth forms or rocks). For both snail species, colonization differed among substrates, with the following rank order of colonization for each species: L. stagnalis (p < 0.006), 1 mm strips > prostrate square > 1 cm strips > rectangle > triangle; Amnicola (p < 0.0001), prostrate square > 1 mm strips > 1 cm strips > triangle > rectangle. Colonization by both species was related positively to degree of contact with the bottom. For L. stagnalis, colonization also was related positively to usable area, which, for the 1 mm strips, was greater than surface area because the foot of L. stagnalis could span the gap between strips, whereas the foot of Amnicola could not. Two predictions emerging from these results are tested with previously published data: 1) numbers of invertebrates should be greater on prostrate than on upright, single-stemmed macrophytes, and 2) numbers of invertebrates should be greater on dissected-leaved than on broad-leaved plants. Published data were equivocal regarding prediction 1). In contrast, prediction 2) was supported strongly, but the data suggest that the relationship between macrophyte dissection and invertebrate density may be strongly affected by species-specific morphology and behavior of invertebrates.

An analysis of the himalayan environment and guidelines for its management and ecologically sustainable development

The impacts of human activities on the bio-geophysical and socio-economic environment of the Himalayas are analysed. The main man-induced activities which have accelerated ecological degradation and threatened the equilibrium of Himalayan mountain ecosystems are stated as: unplanned land use, cultivation on steep slopes, overgrazing, major engineering activities, over-exploitation of village or community forests, lopping of broad leaved plant species, shifting cultivation (short cycle) in north-east India, tourism and recreation. Monoculture in forests, erosion and landslides have resulted in one–third of the total Himalayan land area becoming environmentally derelict. Cold desert conditions prevail in 41,500 km2 of north-west Himalayas and are encouraged by traditional pasturalism. The geo-morphological conditions are major factors responsible for landslides which cause major havoc every year in the area. Other physical problems exist, such as eutrophication, drying up of the natural springs, the recession of the glaciers and changes in surface and ground water hydrology. Wild fauna, like musk deer (Moschus mischiferus) and the snow leopard (Panthera uncia), are now under threat partially due to changes in their habitat and the introduction of exotic plant species. Population pressure and migration are major factors responsible for poverty in the hills. The emigration of the working male population has resulted in the involvement of women as a major work-force. This work includes trekking for hours to collect fodder, timber and drinking water in addition to household duties. Guidelines, with special emphasis on the application of environmental impact assessments for the management of the Himalayas, are proposed.

Late Cretaceous-Cenozoic history of deciduousness and the terminal Cretaceous event

Deciduousness in mesic, broad-leaved plants occurred in disturbed, middle-latitude environments during the Late Cretaceous. Only in polar environments in the Late Cretaceous was the deciduous element dominant, although of low diversity. The terminal Cretaceous event resulted in wide-spread selection for plants of deciduous habit and diversification of deciduous taxa, thus leaving a lasting imprint on Northern Hemisphere vegetation. Various environmental factors have played important roles in subsequent diversification of mesic, broad-leaved deciduous taxa and in origination and decline of broad-leaved deciduous forests. Low diversity and rarity of mesic deciduous plants in the post-Cretaceous of the Southern Hemisphere indicate that the inferred “impact winter” of the terminal Cretaceous event had little effect on Southern Hemisphere vegetation and climate.

Platinum and palladium in roadside dust

Automobile catalytic converters apparently release significant quantities of platinum and palladium to the roadside environment. Dust samples collected from broad-leaved plants contained as high as 0.7 ppm of platinum and 2.5 times less palladium. Rains may wash this concentrate into local water systems or the ocean. 8 references, 1 table.

Comparative Diets of Rambouillet, Barbado, and Karakul Sheep and Spanish and Angora Goats

Diets of Rambouillet, Karakul, and Barbado sheep (Ovis aries) and Spanish and Angora goats (Capra hircus) grazing in 3 plant communities in western Texas were determined by microhistological analysis of fecal samples. Grasses were commonly the major foods of all sheep breeds as well as Angora goats. Forbs were major diet items of all breeds of sheep and goats when they were readily available. Spanish goats, and to a lesser extent Angora goats, relied heavily on browse. Barbado sheep consumed more browse than did Rambouillet or Karakul sheep. Diets of Rambouillet and Karakul sheep overlapped considerably, whereas diets of Rambouillet sheep and Spanish goats were quite dissimilar. Barbado sheep appeared to occupy a food niche intermediate between that of the goats and the other sheep breeds. Spanish and Angora goats exhibited the strongest tendency and Karakul sheep exhibited the least tendency to selectively graze. Neither Barbado nor Karakul sheep consumed sufficient amounts of undesirable shrubs to be considered valuable for brush suppression. Rangeland forage utilization and total meat and fiber production could potentially be enhanced by identifying breeds of sheep or goats with the physical capabilities and diet versatility to better adapt to the currently available forage resource. Goats are generally more efficient at suppressing brush than cattle or sheep since they tend to select a wider variety of plants (Merrill and Taylor 1976). They also have the ability to shift their diet from herbaceous broad-leaved plants to shrubs (Scifres 1980). Goats are hardy and adapted to feed over rugged terrain, and can be combined with sheep and cattle to utilize vegetation which otherwise would be used very little (Campbell et al. 1962). Goats utilize a broader spectrum of plants than sheep, generally exhibit a greater tendency to browse, and therefore more efficiently utilize brush-infested rangeland (Maher 1945; Wilson et al. 1975). However, Malechek and Leinweber (19721 reaorted that grasses were readilv selected hv

Foods selected by blue grouse (Dendragapus obscurus fuliginosus)

The spring and summer diet was determined from 811 blue grouse crops collected from 1957 through 1966 near the town of Campbell River on Vancouver Island. Main foods eaten were conifer needles, broad-leaved vegetation, flowers, fruits, and invertebrates. More than 80% of the plant diet was from nine species. Most foods were selected and selection varied with season, sex, and age. In the spring, females apparently ate more broad-leaved plants than did males, and chicks up to approximately 3 weeks of age fed largely on invertebrates, mainly ants (Formicidae). We attempt to explain selection by relating known nutrients in plants and animals to their use as food. Selection may be partly explained by availability, nutrients, and the nutritional requirements of grouse. Nutrients apparently selected most frequently were ash and nitrogen. The diet of females in May and June seemed richer than that of males in ash, nitrogen, and magnesium. In June, chicks had a diet likely higher in nitrogen, phosphorus, and potassium but lower in carbohydrate, fat, and calcium when compared with adults. The diet of blue grouse compared with that recommended for some other grouse was possibly deficient in ash, phosphorus, and calcium. We postulate food on the summer range might limit populations of blue grouse by the amount of nitrogen and minerals, especially calcium, available to hens in spring and by a range of nutrients available to very young chicks.

The Phenoxy Herbicides: CAST

The phenoxy herbicides, 2,4-D, 2,4,5-T, MCPA, silvex and related materials, are selective herbicides widely used in crop production and in the management of forests, ranges and industrial, urban and aquatic sites. These chemicals are related to naturally occurring plant growth regulators. They kill plants by causing malfunctions in growth processes. Broad-leaved plants are generally susceptible to the phenoxy herbicides, whereas most grasses, coniferous trees and certain legumes are relatively resistant.The phenoxy herbicides are used to control broad-leaved weeds in wheat, barley, rice, oats, rye, corn, grain sorghums and certain legumes. Such uses increase yields, improve product quality and reduce production costs. The phenoxy herbicides are used in forests to suppress unwanted hardwood trees and brush, to reduce competition with conifers already established or to prepare sites for the regeneration of conifers. They are used on grazing lands to control unpalatable and noxious plants and to kill brush and small trees that reduce the productivity of pastures and ranges. 2,4-D and other phenoxys are used in canals, ponds, lakes and waterways to kill floating weeds such as water hyacinth, submerged weeds such as pond-weeds, and emergent and shoreline plants such as cattails and willows. Industrial and urban uses include control of brush on utility and transportation rights of way, control of dandelions, plantains and other weeds in turf and suppression of ragweed, poison ivy and other plants of public health importance.The principal hazard in the use of the phenoxys is to crops and other valuable plants either within the treated area or nearby. Treated crops and forest trees can be injured through accidental overdosing, improper timing of treatments, unusual weather conditions and other causes. Injury to nearby crops and ornamentals can result from drift of droplets or vapors of the spray. Such losses are largely preventable through the use of proper formulations and spray equipment and the exercise of good judgment.The phenoxy herbicides are predominantly toxic to green plants and are much less toxic to mammals, birds, fish, reptiles, shellfish, insects, worms, fungi and bacteria. When properly used, they do not occur in soils and water at levels harmful to animals and microorganisms. They do not concentrate in food chains and do not persist from year to year in croplands. They are detectable only rarely in food and then only in insignificant amounts.A highly poisonous kind of dioxin called TCDD is an unavoidable contaminant in commercial supplies of 2,4,5-T and silvex. The amount present in currently produced formulations of 2,4,5-T and silvex is not enough to alter the toxicological properties of these preparations or to endanger human health or to affect plants or animals in the environment.The phenoxy herbicides are widely used because they are more efficient and usually less hazardous and less injurious to the environment than alternative methods. Use of these chemicals is estimated to reduce the cost of production of the crops on which they are used by about 5% and to reduce overall agricultural production costs in the United States by about 1%. Uses in forests and nonagricultural situations provide additional savings. If the phenoxys were no longer available, the cost of food, forest products, electric power, transportation and governmental services would be higher. These costs would be borne by consumers.

Diurnal Size Fluctuation in Opuntia Stem

Observations made on stem dimensions of Opuntia show diurnal fluctuations comparable to those in broad-leaved plants but in opposite phase. Opuntia stems increase in size during daylight hours and decrease in the dark. The behavior may be related in part to the unusual stomatal response associated with the biochemical pattern of acid fixation in the dark.

A Morphological and Chemical Study of Populus Acuminata Rydberg

Evidence from morphology, flavonoid chemistry, and field observations suggests thatPopulus acuminata is of hybrid origin. The putative parents areP. angustifolia, the narrow leaf cottonwood, and deltoid leaved plants that are assigned toP. sargentii (P. deltoides var.occidentalis), P. fremontii, orP. wislizenii (P. fremontii var.wislizenii). Populus angustifolia exhibits a series of flavonol glycosides (kaempferol, quercetin, and myricetin) in its leaves. By contrast, the major leaf flavonoids of the broad leaved plants are flavone glycosides (apigenin and luteolin).Populus acuminata is intermediate between the suspected parents in morphological features. Additionally, the leaves of mostP. acuminata plants contain the exact summation of the flavonoid compounds characteristic of the putative parents. A diploid chromosome number of 2n = 38 was obtained for six plants, which confirms the one previous report for the species. Meiosis was regular in all cases. Correlated data indicate that the majority of plants ofP. acuminata represent F1 hybrids and that complex hybridization is not common. Evidence from morphological and chemical studies is presented to show that in certain instances backcrossing to both parents has occurred. Results gathered in this study show thatP. ×andrewsii is undoubtedly “typical”P. acuminata, but the type specimen is from a sucker shoot, and thus has been interpreted as a backcross toP. sargentii. Populus acuminata var.rehderi is not considered worthy of taxonomic recognition.

Syntheses and Herbicidal Activities of Dithiocarbamates

Several dithiocarbamates were synthesized and their herbicidal activities to radish and barnyardgrass were examined. Some benzyl N, N-dialkyldithiocarbamates such as N-methyl-N-ethyl-, N-methyl-N-n-propyl-, N, N-diethyl- and N, N-diisopropyl-dithiocarbamates showed high activity to these plants, but N-monoalkyl-, N, N-diaryl- and N, N-diaralkyl-dithio- carbamates were not so active. Some substituted benzyl N, N-dialkyldithiocarbamates such as 4-dimethylaminobenzyl N-methyl-N-ethyldithiocarbamate and 4-methoxybenzyl N, N-diethyldithiocarbamate showed high activity to broad-leaved plants. Substituted benzyl N, N-dialkyldithiocarbamates except 4-cyanobenzyl N, N-diisopropyldithiocarbamate, however, were less active to graminaceous plants.