Fig. 3

Mechanical properties and deformation analysis of etiolated Arabidopsis hypocotyls under tension and creep experiments. A–C Exemplary force–displacement curve (A), force plotted versus actuator or landmark-assessed displacement (B), and corresponding hypocotyl images (C) from an experiment ending in breakage. Three red segments in A mark the points corresponding to measurements in B and the first three images in C; the final image is captured immediately after breakage. The force increase between the first two segments and the strain from the first two images were used to compute Young’s modulus. Landmark-based strain (white arrows) was 2.09% for the first image pair and 0.88% for the second, whereas sticker-based strain (black arrows) was higher (5.90% and 4.57%) due to slippage. D,E Young’s modulus (D) and ultimate stress (E for Col-0 and xxt1 xxt2 hypocotyls are shown; in the boxplots red lines denote the median, boxes span the first and third quartiles, whiskers extend to values within 1.5 × IQR, and dots represent individual measurements. Col-0 (n = 10) differs significantly from xxt1 xxt2 (n = 8 for modulus; n = 7 for stress) (t-test, p = 0.0031 and p = 0.00007). F–H Exemplary force–displacement curve (F) with force plotted versus actuator or landmark-assessed displacement (G) and corresponding hypocotyl images (H). In the final stage, indicated by three red segments in F corresponding to the measurements in G and images in H, grip displacement mainly caused sample slippage with negligible hypocotyl strain. Landmark-based strain (white arrows) is 0.28% for the first image pair and 0.36% for the second, whereas sticker-based strain (black arrows, region marked by black asterisks) is 5.19 and 4.17%, respectively. I,J Exemplary creep experiment results from the basic setup. I Displacement rates for landmarks (blue) and actuator grips (red) plotted over time, computed over 300-s intervals from landmark positions (white arrows) or actuator positions recorded in a.csv file. J Corresponding hypocotyl images