The control of blooming in Sauromatum guttatum (Araceae) by darkness

Abstract

When an inflorescence of Sauromatum guttatum Schott blooms, the spathe unfolds and exposes the spadix. After spathe-opening, the terminal portion of the spadix (appendix) undergoes a dramatic respiratory climacteric (RC) which is characterized by the production of copious quantities of CO2 and the concomitant warming of the appendix.In experiments conducted on inflorescences raised under continuous irradiation, we have shown that darkness is the environmental factor which triggers the blooming. The moment of the peak in CO2 (or heat) production during the RC was used as an index of blooming.The darkness which triggers the RC is "perceived" by the staminate flowers, borne on the spadix beneath the appendix. Darkness is also involved in (1) regulating the lag time between the inductive dark period and the moment of the peak in the RC, and (2) opening the spathe.