Some Effects of Metabolic Inhibitors, Temperature, & Anaerobic Conditions on Stomatal Movement

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Abstract
The new method of measuring stomatal apertures from impressions of tobacco leaf disks cast in silicone rubber has been applied to an investigation of factors which affect stomatal opening and closing. Metabolic inhibitors, in addition to the a-hydroxysulfonates previously described, including phenylmercuric acetate, Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), potassium arsenate, sodium arsenite, salicylaldoxime, sodium sulfide, hydroxylamine, and chlorogenic acid prevent the opening of stomata in the light, and induce closure of already open stomata in the light to the same aperture by inhibiting the opening reactions. Azide is different because at appropriate concentrations it not only inhibits opening in the light and induces closing in the light, but also prevents stomatal closure in the dark. The concentration of azide needed for complete inhibition of closing is higher than that required to prevent opening, hence the reactions for opening and closing are probably different. The stomata of leaf disks at 30[degree]C open much wider than those of disks kept at 10[degree]. When disks are transferred from 1 temperature to the other, the stomata quickly open or close to the aperture of the steady state dictated by the final temperature. These results, together with those obtained with metabolic inhibitors, suggest that the biochemical reactions responsible for opening and closing occur simultaneously in the light. External oxygen is required for the opening of stomata, but not for the maintenance of opening or for closing.