Fig 1.
Clamping of hypocotyls in microtensile testing devices and schematic stress-strain curve.
Fig 2.
Hypocotyl lengths and cross sections of samples tested with experimental setup 1 (horizontal test, water vapour).
For each series n > 18 replicas were analyzed. Error bars depict standard deviation.
Fig 3.
Influence of variations in growth conditions on the geometry of four day old dark grown hypocotyls.
A) Length vs. growth conditions. Increased water content in the medium as well as a higher temperature during germination leads to an increase in length. A thinner layer of agarose appears to reduce the nutrient supply sufficiently to slightly decrease length growth. B) Cross-sections vs. growth conditions. Only the combination of an increased temperature during germination and higher water content in the medium induced a slight reduction in cross-section, while the individual alterations and a reduction in the amount of medium had no effect.
Fig 4.
Density and cellulose content of dark grown hypocotyls.
A) Density is analyzed as dry weight per wet volume (seed batch 1, n > 14). B) Cellulose content measured as μg hexoses per cell wall material (CWM). * P < 0.05, ** P < 0.01, n.s.: no significant difference.
Fig 5.
Tensile stiffness and fracture stress of series 1a (round, light symbols), 1b (round, dark symbols), 2a (square, light symbols, 2b (square, dark symbols).
Plotted against age, lengths and cross sectional areas. For each set n>18 samples were analyzed respectively.
Fig 6.
Comparison of the results of the micromechanical tests with samples tested submerged in an osmotic liquid (green, Setup 2) and in air, kept in the native state by a humidifier (blue, Setup 1) for tensile stiffness (A) and fracture stress (B). The change in diameter from the initial value before the tensing to the point of maximal stress in the submerged setup (C).