Roger W. Ferenbaugh

Bio: Roger W. Ferenbaugh is an academic researcher from University of Montana. The author has contributed to research in topics: Photosynthesis & Phaseolus. The author has an hindex of 1, co-authored 1 publications receiving 106 citations.

Effects of simulated acid rain on phaseolus vulgaris L. (fabaceae)

Abstract: A B S T R A C T Experiments were performed to determine the effects of simulated acid rain on Phaseolus vulgaris L. At pH values below 3, plants exhibited a failure to attain normal height, had necrotic and wrinkled leaves, excessive and adventitious budding, and premature abscission of primary leaves. Histologically, leaves had smaller cells, less intercellular space, and smaller starch granules within the chloroplasts. Respiration rates of the treated plants increased only slightly at low pH values. Apparent rates of photosynthesis, however, increased dramatically. Both carbohydrate production and root biomass were reduced by low pH treatments, and application of Congo red indicator to the acid-treated leaf tissue showed that the cell contents were acidified to a pH of below 4.0.

Plant compensation for arthropod herbivory

Abstract: Plant compensation for arthropod damage is a general occurrence of considerable importance in both natural and agricultural systems. In natural systems, plant species that can tolerate or compensate (e.g. recover equivalent yield or fitness) for herbivore feeding have obvious selective advantages that lead to genotype maintenance. Scientists publishing in this area often cite an optimal strategy for enhancing fitness (90, 108). In agricultural crops, reports of plant compensation mostly are concerned with yields rather than fitness (164). However, variation in compensatory response also affects sampling strategies and economic threshold levels [sensu Stern (166)] and provides viable tactic for breeding insect resistance to key arthropod pests into plants. Not surprisingly, the relative importance of the various forms of compensation in agricultural and natural systems is still relatively unknown. Therefore, a primary purpose for this review is to integrate the forms of compensation reported in the literature in the context of natural and agricultural habitats. Several previous reviews and articles have had a significant impact on the development of an understanding of plant compensatory responses. Some provide extensive lists of examples of plant compensation and the pest-yield relationship (4, 164), while others stress the complexity and interrelatedness

Air density 2.7 billion years ago limited to less than twice modern levels by fossil raindrop imprints

Abstract: Experiments dropping raindrops onto ash combined with raindrop fossil imprints yield an upper limit for air density in the Archaean. About 2.7 billion years ago, towards the end of the Archaean period, a rain shower left its mark on ash deposits from a volcanic eruption in what is now the South African veldt. As the ash hardened to form tuff rock, the crater-like imprints of the individual raindrops were fossilized. An analysis of these imprints, aided by comparison with similar prints formed during the 2010 Eyjafjallajokull eruption in Iceland, suggests that air density during the Archaean was no more than twice modern levels. At that time, the Sun was dimmer than it is today, but the climate was warm. Most theories to explain this 'Faint Young Sun' paradox have assumed that the atmosphere was denser in the Archaean than it is now, and that the greenhouse effect was stronger, but this latest work seems to rule out higher carbon dioxide levels; nitrogen-pressure broadening remains unlikely, but possible. According to the ‘Faint Young Sun’ paradox, during the late Archaean eon a Sun approximately 20% dimmer warmed the early Earth such that it had liquid water and a clement climate1. Explanations for this phenomenon have invoked a denser atmosphere that provided warmth by nitrogen pressure broadening1 or enhanced greenhouse gas concentrations2. Such solutions are allowed by geochemical studies and numerical investigations that place approximate concentration limits on Archaean atmospheric gases, including methane, carbon dioxide and oxygen2,3,4,5,6,7. But no field data constraining ground-level air density and barometric pressure have been reported, leaving the plausibility of these various hypotheses in doubt. Here we show that raindrop imprints in tuffs of the Ventersdorp Supergroup, South Africa, constrain surface air density 2.7 billion years ago to less than twice modern levels. We interpret the raindrop fossils using experiments in which water droplets of known size fall at terminal velocity into fresh and weathered volcanic ash, thus defining a relationship between imprint size and raindrop impact momentum. Fragmentation following raindrop flattening limits raindrop size to a maximum value independent of air density, whereas raindrop terminal velocity varies as the inverse of the square root of air density. If the Archaean raindrops reached the modern maximum measured size, air density must have been less than 2.3 kg m−3, compared to today’s 1.2 kg m−3, but because such drops rarely occur, air density was more probably below 1.3 kg m−3. The upper estimate for air density renders the pressure broadening explanation1 possible, but it is improbable under the likely lower estimates. Our results also disallow the extreme CO2 levels required for hot Archaean climates8.

Leaf surface and histological perturbations of leaves of phaseolus vulgaris and helianthus annuus after exposure to simulated acid rain

Abstract: Initial injury to adaxial leaf surfaces of Phaseolus vulgaris and Helianthus annuus occurred near trichomes and stomata after exposure to simulated sulfate acid rain. Lesion frequency was not correlated with density of either stomata or trichomes but was correlated with degree of leaf expansion. The number of lesions per unit area increased with total leaf area. Results suggest that characteristics of the leaf indumentum such as development of trichomes and guard cells and/or cuticle thickness near these structures may be involved in lesion development. Adaxial epidermal cell collapse was the first event in lesion development. Palisade cells and eventually spongy mesophyll cells collapsed after continued, daily exposure to simulated rain of low pH. Lesion development on Phaseolus vulgaris followed a specific course of events after exposure to simulated rain of known composition, application rate, drop size frequency, drop velocities, and frequency of exposures. These results allow development of further experiments to observe accurately other parameters, such as nutrient inputs and nutrient leaching from foliage, after exposure to simulated sulfate acid rain.

Differential responses of plant foliage to simulated acid rain

Abstract: Experiments were performed to show the responses of foliage of several clones of Tradescantia sp., Pteridium aquilinum, Quercus palustris, and Glycine max to simulated acid rain. These experiments were performed to (a) predict the relative sensitivities of foliage of these plants to acid rain, and (b) identify leaf surface and anatomical alterations to simulated acid rain that may be used to diagnose acid rain injury. Plants were exposed to simulated rain at pH levels of 5.7, 3.4, 3.1, 2.9, 2.7, 2.5, and 2.3.