Differential response of CO2 uptake parameters of soil- and sand-grown phaseolus vulgaris (L.) plants to absorbed ozone flux.

Shoots of a soil- or sand-grown dwarf bean variety were exposed to O(3) concentrations in the range of 500 to 900 ppb for up to 5 h. The measured exchange rates of water vapor and CO(2) during exposures were used to calculate stomatal and mesophyll conductances averaged across all leaves. Changes in conductances were related to exposure duration and absorbed O(3) totals (AOT).

Ozone concentration in leaf intercellular air spaces is close to zero.

Transpiration and ozone uptake rates were measured simultaneously in sunflower leaves at different stomatal openings and various ozone concentrations. Ozone uptake rates were proportional to the ozone concentration up to 1500 nanoliters per liter. The leaf gas phase diffusion resistance (stomatal plus boundary layer) to water vapor was calculated and converted to the resistance to ozone multiplying it by the theoretical ratio of diffusion coefficients for water vapor and ozone in air (1.

Inhibition of photosynthesis of sunflower leaves by an endogenous solute and interdependence of different photosynthetic reactions.

Photosynthesis of Helianthus annuus L. leaves was transiently inhibited and respiration was stimulated when a leaf was detached from the plant by cutting the petiole under water. These effects were caused by a solute which was released by cutting and was transported by the transpiration stream to the leaf blade.

Assimilatory Power (Postillumination CO(2) Uptake) in Leaves: Measurement, Environmental Dependencies, and Kinetic Properties.

Assimilatory power was measured in ten C(3) species by means of a rapid-response gas exchange device as the total amount of CO(2) fixed in N(2)-CO(2) atmosphere after switching the light off. Different steady-state levels of the assimilatory power were obtained by varying light intensity and O(2) and CO(2) concentrations during the preexposition periods in the leaf chamber.Within the limits of the linear part of the CO(2) curve of photosynthesis in N(2), the assimilatory power is constant, being sufficient for the assimilation of about 20 nanomoles CO(2) per square centimeter leaf.

Growth rate-reserve content relationship as influenced by irradiance, CO2 concentration, and temperature.

The patterns of the CO2 exchange of single vegetative bean plants were monitored during steady state exchange and after lowering the irradiance, the CO2 concentration, or the temperature. The measured patterns were used to calculate the dynamics of the rate of synthesis of structural dry matter and of the amount of the reserve materials during the experiments. The rate of synthesis of structural dry matter was assumed to be proportional to growth respiration (total minus maintenance).