Effects of chilling on Episcia and Dieffenbachia
McMahon, M.J. | Pertuit, A.J. Jr | Arnold, J.E.
Leaves of chilled 'moss-Agate' Episcia (mart.) plants exhibited direct chilling injury (i.e., watersoaked browning of leaf blade interveinal areas within 24 h of exposure to low temperature) immediately following exposure in darkness to 10C for 0.5 or 1.0 h. Chlorophyll fluorescence peak : initial ratios and terminal : peak ratios of chilled Episcia were reduced 20% and 25%, respectively, 3 h after chilling, a result suggesting possible photosystem II damage. Total leaf chlorophyll content was reduced by 17% within 3 h of chilling and CO2 uptake also was reduced at this time. Leaves of chilled 'Rudolph Roehrs' Dieffenbachia maculata (Lodd.) (D. Roehrsii Hort.) plants expressed no visible injury within 24 h of 1.2C chilling in darkness for 36,48, or 60 h, but CO2 uptake was reduced by 70% compared to the control 3 h after chilling. Visible injury began to appear 27 h after chilling, and the older leaf blades of all chilled plants exhibited a watersoaked appearance 75 h after chilling. Chlorophyll fluorescence peak : initial ratios of chilled Dieffenbachia did not vary, and terminal : peak ratios were not reduced until 147 h after chilling, when the injured tissue was extremely flaccid and translucent. Chilling reduced the chlorophyll content of Dieffenbachia by 10% in some plants 27 h after chilling and by 35% in all plants 75 h after chilling. Transpiration rate was reduced and stomatal diffusive resistance increased 27 h after chilling.
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