The effect of mechanical perturbation on the growth and development of wheat

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Student thesis: Doctoral ThesisDoctor of Philosophy

Original languageEnglish
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Award date2020
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Abstract

Plants sense mechanical stimuli such as bending of the stem caused by the force of wind on the plants aerial surface. The response is known as Thigmomorphogenesis and includes a range of responses of which the most commonly reported is an immediate cessation of growth. This is followed by period of lag before growth resumes at its normal rate, which leads to shorter plants. The effect of Thigmomorphogenesis has been well characterised in
diocots, and the use of mechanical treatment has been adapted for the control of height in commercial vegetable transplant production. However, the response of monocots is less understood. Wheat is the most important cereal crop in the UK, though it is prone to lodging due to factors including strong winds. Mechanical properties of the stem influence susceptibility to lodging and may be affected by exposure to repeated low-levels of mechanical perturbation. The purpose of this study was to better understand the response of monocots to mechanical stimulation. Experiments were conducted under static air
greenhouse conditions and natural wind conditions outside, with brushing treatment applied using a purpose-built rig. Plants responded significantly to doses as small as 1 brushstroke. Increasing brushing dose in increments to 20 resulted in a decrease in height. Stems were significantly narrower than controls, with treatment affecting the lowest internodes most. Applying brushing during tillering stages resulted in an increase in tiller numbers, leading to an increase in the number of flowering spikes in greenhouse grown plants, but not plants
grown outside. Brushing young greenhouse grown plants resulted in smaller grains in main tiller spikes. There was no effect on grain yield of plants grown outside. There was little difference in stem mechanical properties at the end of flowering, though an increase in Young’s modulus was found in the stems of senesced mature plants