A Proposed Drought Response Equation Added to the Münch-Horwitz Theory of Phloem Transport.

Theoretical and experimental evidence for an effect of sieve tube turgor pressure on the mechanisms of phloem unloading near the root tips during moderate levels of drought stress is reviewed. An additional, simplified equation is proposed relating decreased turgor pressure to decreased rate kinetics of membrane bound transporters. The effect of such a mechanism would be to decrease phloem transport speed, but increase concentration and pressure, and thus prevent or delay negative pressure in the phloem.

Carbon partitioning patterns of mycorrhizal versus non-mycorrhizal plants: real-time dynamic measurements using CO.

Gas exchange and carbon allocation patterns were studied in two populations of Panicum coloratum, an Africa C-4 grass. The plants were grown in split-root pots, containing partially sterilized soil, with one side either inoculated (I) or not inoculated (NI) with a vesicular arbuscular (VA) mycorrhizal Fungus, Gigaspora margarita. Net carbon exchange rates (CER) and stomatal conductances were measured with conventional gas exchange apparatus, and carbon assimilation, translocation, and allocation were measured using photosynthetically-fixed CO .

Cell wall elasticity: I. A critique of the bulk elastic modulus approach and an analysis using polymer elastic principles.

The traditional bulk elastic modulus approach to plant cell pressure-volume relations is inconsistent with its definition. The relationship between the bulk modulus and Young's modulus that forms the basis of their usual application to cell pressure-volume properties is demonstrated to be physically meaningless. The bulk modulus describes stress/strain relations of solid, homogeneous bodies undergoing small deformations, whereas the plant cell is best described as a thin-shelled, fluid-filled structure with a polymer base.

Low night temperature effect on photosynthate translocation of two C grasses.

Translocation of assimilates in plants of Echinochloa crus-galli, from Quebec and Mississippi, and of Eleusine indica from Mississippi was monitored, before and after night chilling, using radioactive tracing with the short-life isotope C. Plants were grown at 28°/22°C (day/night temperatures) under either 350 or 675 μl·l CO. Low night temperature reduced translocation mainly by increasing the turn-over times of the export pool.

Carbon import among vegetative tillers within two bunchgrasses: assessment with carbon-11 labelling.

Carbon allocation among bunchgrass tillers was examined with carbon-11 (CO) steady state labelling. Labelled carbon was continuously transported from parent tillers to anatomically attached daughter tillers at a time when morphological characteristics indicated that tiller maturation had occurred. Steady state levels of import into monitored daughter tillers increased within 30 min of either defoliation or shading.

Effects of Temperature and CO(2) Enrichment on Carbon Translocation of Plants of the C(4) Grass Species Echinochloa crus-galli (L.) Beauv. from Cool and Warm Environments.

Plants of Echinochloa crus-galli from Québec and Mississippi were grown under two thermoperiods (28 degrees C/22 degrees C, 21 degrees C/15 degrees C) and two atmospheric CO(2) concentrations (350 and 675 microliters per liter) to examine possible differential responses of northern and southern populations of this C(4) grass species. Translocation was monitored using radioactive tracing with short-lived (11)C. CO(2) enrichment induced a decrease in the size of the export pool in plants of both populations.

Toward the engineering of photosynthetic productivity.

This article is a review of progress towards a general quantitative theory of photosynthetic productivity or autotrophy in plants. It is not intended to be an exhaustive review, but rather a perspective of the autotrophic puzzle and current approaches to its solution. The review describes attempts to quantitatively describe a generalized plant based on theoretical expressions for its component parts.

Concentration-dependent Unloading as a Necessary Assumption for a Closed Form Mathematical Model of Osmotically Driven Pressure Flow in Phloem.

Previous attempts to model steady state Münch pressure flow in phloem (Christy and Ferrier. [1973]. Plant Physiol.

Concentration dependencies of some effects of ethylene on etiolated pea, peanut, bean, and cotton seedlings.

The effects of a series of concentrations of ethylene (10, 20, 40, to 10,240 nl/l) on elongation, diameter, and geotropism of the stems and roots of etiolated seedlings of Pisum sativum L., Arachis hypogea L., Phaseolus vulgaris L.

An effect of light on the production of ethylene and the growth of the plumular portion of etiolated pea seedlings.

The production of ethylene by etiolated pea epicotyls (Pisum sativum L., cv. Alaska) is confined to the plumule and plumular hook portion of the epicotyl, and occurs at a rate of about 6 mul.

Ethylene as a factor regulating the growth of pea epicotyls subjected to physical stress.

Pea epicotyls (Pisum sativum, cv. Alaska) were enclosed in chambers in which their elongation was restricted by means of a foam neoprene stopper or by a medium of glass beads. These treatments increased evolution of ethylene and resulted in reduced length and increased diameter of both the internodes and the cells of the internodes.