Mechanical properties of plants and underlying
structure-property relationships are important for
agricultural purposes as well as for biomimetic concepts.
In this study, the effect of mechanical stimulation on
morphology and bending properties of the stalk was
investigated for Sorghum bicolor (Poaceae), a widely used
drought-tolerant biomass grass. An experimental set-up
allowing for defined growth and mechanical perturbation
(flexing) during a defined growth period was designed.
Mechanical properties of individual internodes of the
stalk were determined by three-point bending tests. We
found that the three investigated lines showed differences
in their general bending strength in the non-stimulated
condition. However, similar high range of bending
strength values was measured for all plant lines after
they underwent the mechanical stimulation procedure.
The anatomy of internode cross-sections was examined
to evaluate structure-property relationships. An increased
thickness of the outer sclerenchymatous tissue was
observed for internodes with higher bending strength
values. Dried internodes fail under lower strains but
showed higher bending strength. These findings show that
mechanosensitivity in sorghum is dependent on genetic
as well as environmental factors. The experimental system
presented here offers new straight-forward possibilities for S. bicolor line selection for applications requiring
mechanical strength of the stalk.