Mechanical Differences Between Free-standing and Supported Wheat Plants, Triticum aestivum L.

The effect of wind sway on the mechanical characteristics ofthe anchorage roots and the stem was investigated in maturewinter wheat (Triticum aestivumL., cv. Hereward). Wheat plantswere field-grown, either supported by a frame, which preventedwind sway, or unsupported (free-standing) and the morphologyand mechanical properties of the stems and the anchorage, ‘coronal’, roots were measured. Wind sway had little influence on either the stem height orear weight of the plants but did affect the mechanical propertiesof the stem. Stems of supported plants were weaker and moreflexible than the stems of free-standing plants. There werealso differences in the anchorage systems between the treatments:supported plants had just under half as many ‘coronal’ anchorage roots as the free-standing plants. This reducedthe anchorage strength of supported plants by a third. These differences in mechanical structure meant that the free-standingplants were more resistant to stem buckling and more resistantto anchorage failure. However, considering the difference inthe need for mechanical strength in plants from the two regimes,these differences were small. This suggests that wheat has inherentmechanical integrity and, as a monocotyledon with no secondarythickening, it differs little structurally between environments. Triticum aestivumL.; thigmomorphogenesis; anchorage; safety factor; mechanical stimulation