Abscisic Acid Effects on Photosynthesis and Transpiration in Geranium Cuttings

Abstract

The effect of root applications of abscisic acid (ABA) on photosynthesis and transpiration in geranium ( Pelargonium ×hortorum ‘ Glacier Crimson’ Syn. Bruni ) cuttings was evaluated using an open infrared CO 2 gas exchange system. At concentrations above 3.8 μM ABA there was a reduction in relative growth rate (RGR), transpiration, and photosynthesis 2 days following treatment. Three hours following treatment with 76 μM ABA there was a maximum decrease in both photosynthetic and transpiration rates. Plants which were treated with 76 μM ABA for 6 or 9 hr showed an inhibition in photosynthesis and transpiration 4 days followiing treatment; however, after 6 days there was no difference between treated and control plants. The reduction in transpiration and photosynthesis reported in this paper may have practical value in the shipment and storage of geranium cuttings.