The Effect of Plant Weight on Estimations of Stalk Flexural Stiffness and Stalk Lodging Resistance

Abstract Background: Stalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-billion dollar a year problem. Stalk lodging occurs when bending moments induced by a combination of external loading (e.g. wind) and self-loading (e.g. the plant’s own weight) exceed the bending strength of plant stems. Previous studies have investigated external loading and self-loading of plants as separate and independent phenomena. However, these two types of loading are highly interconnected and mutually dependent. The purpose of this paper is twofold: (1) to investigate the combined effect of external loads and plant weight on the flexural response of plant stems, and (2) to provide a generalized framework for accounting for self-weight during mechanical phenotyping experiments used to predict stalk lodging resistance. Results: A method of properly accounting for the interconnected relationship between self-loading and external loading of plants stems is presented. The interconnected set of equations are used to produce user-friendly applications by presenting (1) simplified self-loading correction factors for a number of common external loading configurations of plants, and (2) a generalized Microsoft Excel framework that calculates the influence of self-loading on crop stems. The effect of self-loading on the bending strength measurements of wheat is examined in detail. A survey of several other plants is conducted and the influence of self-loading on their structural response is also presented. Conclusions: The self-loading of plants plays a potentially critical role in determining the structural response of plant stems. Equations and tools provided herein enable researchers to account for the plant’s weight during mechanical phenotyping experiments used to determine the flexural rigidity and bending strength of plant stems. Results demonstrated that ignoring the self-loading of some plants can result in errors of 25% for flexural stiffness and 20% for bending strength.