Relationship of Temperature to Stomatal Aperture and Potassium Accumulation in Guard Cells of Vicia faba

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Abstract
Epidermal strips of V. faba were floated on 10 mM KCl at various temperatures and for several time periods. The diameter of the stomatal aperture was determined microscopically and K+ content was estimated and expressed as the per cent of the guard cell stained. Stomatal opening was associated with increased K+ in guard cells, but the quantitative association was modified both by time and temperature. At low temperatures (0-20.degree. C) there was a prolonged Spannungsphase while at higher temperatures (30-45.degree. C) motorphase was exhibited. During the motorphase there was a rapid opening of the stomates which was highly correlated with K+ influx. At treatment periods of 360 min and temperatures higher than 25.degree. C there appeared to be a maintenance phase during which K+ concentration of the guard cells decreased without an equivalent decrease in aperture.