DOI: 10.5061/dryad.0p2ngf28k
title: Data from: Negative shoot phototropism in a climber and an epiphyte

description: When a root-climber Ficus pumila and an epiphyte Peperomia quadrangularis
 were exposed to a light gradient, over 90% of the shoots grew away from
 light. This is the first demonstration of negative phototropism in these
 species. Whereas in climbers, negative phototropism of the shoots may help
 in remote location of support, its function in epiphytes remains
 uncertain.
description: This is an experimental test of the occurrence of negative
 phototropism in an adventitious-root climber <em>Ficus pumila
 </em>L. from S.E. Asia, and a neotropical epiphyte
 <em>Peperomia quadrangularis</em> A.Dietr. The plant material
 was obtained from cultivated stock. Rooted cuttings of <em>Ficus
 pumila </em>were planted in round pots 11 cm in diameter and 10 cm
 tall, and those of <em>P. quadrangularis in </em>square pots
 6.5 cm wide and 8 cm tall. The test for phototropic growth involved
 exposing young plants to a gradient of light intensity from fluorescent
 sources and recording the growth direction of new shoots. 
 In the experiment with <em>F. pumila</em> the method
 described in Wyka (2023, Tree Physiol 43:1874–1885) was used. Each young
 potted plant (n=33) was placed centrally in a larger (22 cm in diameter,
 95 mm deep) pot and stabilized by filling the space in the outer pot with
 keramsite. The outer pot was inserted into a 30 cm tall tube made of
 glossy white photo paper. Half of the inner surface of the tube was lined
 with black landscape cloth, dividing the horizon of each plant into equal
 black and white surfaces . These setups were arranged on a table under
 Sylvania Pentron fluorescent lamps, with the black and white surfaces
 oriented in random directions. The plants were maintained under direct
 photosynthetic photon flux density PPFD=50.9 ± 7.2 µmol
 m<sup>-2</sup> s<sup>-1</sup> (mean ± st. dev.;
 n=20 measurements), measured with sensor held horizontally at the plant
 apex. The horizontal gradient of scattered light was measured by holding
 the sensor at the plant apex and orienting it sideways towards the center
 of the white and the black surface. The ratio of PPFD scaterred  from the
 white surface to that scattered from the black surface was on average 2.9
 (n=20). Plants were checked weekly and considered to have reached the end
 point when the main shoot reached the tube.  The
 experiment with <em>Peperomia quadrangularis </em>used a
 different set up. The light gradient was created by suspending a black
 cloth along the middle of a 1 m×1.4 m growing table and mounting Philips
 Master TLD fluorescent tubes above the edges of the table. Plants were
 arranged on each side of the cloth at 10 cm distance from the cloth (n=36
 plants in total). The PPFD of light scattered from the black cloth at
 plant apex was 3.1-3.7% of the light arriving directly from the lamp (1.9
 ± 0.3 µmol m<sup>-2</sup> s<sup>-1 </sup>vs. 60.6
 ± 11.6 µmol m<sup>-2</sup> s<sup>-1</sup>, means ±
 st. dev., n=12 measurements in each direction).  In
 both species, the plant response to light gradients was measured as the
 angle of deviation between the direction of shoot growth and the nearest
 point of the black surface. 
description: # Data for "Negative shoot phototropism in a climber and an
 epiphyte"
 [https://doi.org/10.5061/dryad.0p2ngf28k](https://doi.org/10.5061/dryad.0p2ngf28k) The data set is organized into two spreadsheets, each containing experimental results for an individual species (*Ficus pumila* and *Peperomia quadrangularis*).  ## Description of the data and file structure *Ficus pumila*: 1. Lengths of shoot projections are given instead of total shoot lengths to facilitate graphic representation of shoot growth direction. The shoots were often arched, therefore their actual lengths were somewhat greater than their projections. 2. Deviation angles are the angles between the projection of the shoot axis and the radius linking the plant base and the middle of the black surface. 3. Angle sign was negative if the shoot was growing to the left of that radius and positive if it was growing to the right. Modulus of the angle was taken for analysis. 4. Discrete choices of shoot growth direction (black vs. white) were assigned on the basis of angle modulus (0 to 90 degrees - growth toward black surface, 90-180 degrees - growth toward white surface). *Peperomia quadrangularis*: 1. Lengths of shoot projections are given instead of total shoot lengths to facilitate graphic representation of shoot growth direction. The shoots were often arched, therefore their actual lengths were somewhat greater than their projections. 2. Two largest shoots per plant (numbered 1 and 2) were measured (unless only  one was present). 3. Deviation angle is the angle between projected shoot axis and the straight line transecting the plant base and perpendicular to the black cloth. 4. Angle sign was negative if the shoot was growing to the left of that line and positive if it was growing to the right. Modulus of the angle was taken for analysis. 5. Discrete choices of shoot growth direction (toward or away from black cloth) were assigned on the basis of angle modulus (0 to 90 degrees - growth toward black cloth, 90-180 degrees - growth away from black cloth). ## Sharing/Access information Not applicable. ## Code/Software Not applicable.