The Induction of Contractile Root Activity in Sauromatum guttatum (Araceae)

Contraction of Sauromatum guttatum roots creates a slow, downward underground corm movement, the corm be-coming covered by a greater amount of soil, and the geophilous plant surviving the dormancy period at a safer soil position. Corm movement of Sauromatum guttatum is only possible if root contraction results in pulling activity. This pulling activity can be quantified using the lifting technique. Measurements of the pulling activity are shown as working curves over time and as the maximum work of a single contractile root. Our results show that root activity varies in individuals cultivated under different parameter conditions. It can be shown that two factors induce root contraction: first, rapid temperature fluctuations during the preceding growth period; second, illumination of the sheath leaves during the actual growth period. However, light induction is, as found here, more important and hierarchically superior, for the temperature effect is only seen in plants whose sheath leaves are not illuminated. Mobility of S. guttatum plants can thus be described as photo-movement. If the light effect is not present, the mobility of S. guttatum may become thermo-movement. However, at present, there is no indication that this movement is oriented to the direction of stimulus.