Decision-Making Underlying Support-Searching in Pea Plants

Abstract

Finding a suitable support is a key process in the life history of climbing plants. Those that find a suitable support have greater performance and fitness than those that remain prostrate. Numerous studies on climbing plant behavior have elucidated the mechanistic details of support-searching and attachment. Far fewer studies have addressed the ecological significance of support-searching behavior and the factors that affect it. Among these, the diameter of supports influences their suitability. When the support diameter increases beyond some point, climbing plants are unable to maintain tensional forces and therefore lose attachment to the trellis. Here, we further investigate this issue by placing pea plants (Pisum sativum L.) in the situation of choosing between supports of different diameters while their movement was recorded by means of a three-dimensional motion analysis system. The results indicate that the way pea plants move can vary depending on whether they are presented with one or two potential supports. Furthermore, when presented with a choice between thin and thick supports, the plants showed a distinct preference for the former than the latter. The present findings shed further light on how climbing plants make decisions regarding support-searching and provide evidence that plants adopt one of several alternative plastic responses in a way that optimally corresponds to environmental scenarios.

Keywords: decision-making; kinematics; plant behavior; plant movement.

Figure 1

A frame representing an exemplar plant approaching the support for (a) the single-support (SS) condition with (b) a graphical representation of its trajectory. A plant approaching the thinner support for (c) the double-support (DS) condition with (d) a graphical representation of its trajectory.

Figure 2

Pearson’s correlation coefficient between the “circumnutation length” and the “amplitude of peak velocity”.

Figure 3

Graphical depiction of the (a) “thin” and “thick” supports; (b) the location of the support in the pot and how it was inserted in the soil. The single-support and double-support conditions are represented in panels (c) and (d), respectively.

Figure 4

Graphical illustration of (a) experimental setup and (b) demonstration of how plants were captured by the infrared cameras.

Figure 5

Graphical representation for some of the considered dependent measures: (a) the distance from the circumnutation gravity center to the origin is represented as a red/dash line; (b) the length of the circumnutation major axis is represented as a blue/dash line; (c) the circumnutation length is represented as a yellow/solid line; (d) the circumnutation area is represented in green.