Foliar Uptake and Translocation of 22NA-Labelled Monodisperse Glycerol Aerosol Particles (0.6 Micron)

摘要

Uptake and translocation of 22Na were determined after labelled aerosol deposition on primary leaves of the 12-14 day old string bean plant, Phaseolus vulgaris var. green pod Landreth. Plants were grown under standardized humidity and light conditions, and following the aerosol exposure they were maintained for a subsequent 24 hour period under one of the following lighting conditions: continuous light, cyclic light, continuous dark. In the last two groups, humidity also was varied systematically. Labelled aerosol was produced as a monodisperse particle by a modified version of the Sinclair-LaMer glycerol generator. Leaf absorption was determined as the radioactivity remaining in the leaf after 6 seconds elution in iso-osmotic mannitol solution (0.36 M). With this elution procedure about 20 percent of the isotope remained fixed in the leaf--a fraction removable only very slowly by continued elution. Compared to light, dark conditions caused nearly total cessation of radioactivity transport to stem and to root. Leaf radioactivity did not change appreciably in dark. Lowered humidity had inhibitory effect on leaf absorption and on normal transport to stem and root maintained photosynthetically. Aerosol exposure caused disturbance of normal leaf metabolism, judged by polarographic assays in sections of exposed leaves which had recuperated from sectioning injury. At atypically high levels of glycerol deposition (18 micrograms/sq cm leaf) O2 uptake was inhibited as well as O2 evolution. However, at the lower levels (e.g. 6 micrograms/sq cm leaf) only O2 evolution was inhibited, showing about half of maximal O2 evolution rates characteristic of this plant. (Author)