Field‐based mechanical phenotyping of cereal crops to assess lodging resistance

Abstract

Plant mechanical failure, also known as lodging, is the cause of significant and unpredictable yield losses in cereal crops. Lodging occurs in two distinct failure modes—stalk lodging and root lodging. Despite the prevalence and detrimental impact of lodging on crop yields, there is little consensus on how to phenotype plants in the field for lodging resistance and thus breed for mechanically resilient plants. This review provides an overview of field‐based mechanical testing approaches to assess stalk and root lodging resistance. These approaches are placed in the context of future perspectives. Best practices and recommendations for acquiring field‐based mechanical phenotypes of plants are also presented.

The Effect of Plant Weight on Estimations of Stalk Lodging Resistance 

“…Several mechanical phenotyping devices have been developed to measure stalk flexural stiffness and / or stalk bending strength [6,22,24,42,43]. A review of these devices is presented in [24]. In general, all these devices apply an external load (e.g., a contact force) to either a single plant or to a group of plants and measure the accompanying deflection of the plant stem(s).…”

“…Standard engineering beam equations are then used to calculate the flexural stiffness and bending strength of the plant sample (e.g. [6,24]). However, the standard engineering beam equations used in these analyses ignore the effect of Body Forces (i.e.…”

“…self-weight) and are therefore error prone. induced by a phenotyping device to the resulting deflection of the stem (δ) using Castigliano's energy method [24,42,43]. In this way, the deflection of the plant is equal to the partial derivative of the internal potential energy of the system with respect to the applied load (F) from the phenotyping device [17]:…”

“…The primary purpose of the first case study was to demonstrate how researchers can determine if the influence of self-weight is a significant factor in a given experiment. In this case study, two loading configurations commonly used to measure stalk bending strength and stalk flexural stiffness are presented [24].…”

“…Stalk flexural stiffness and stalk bending strength (see box 1 for definitions) are key mechanical phenotypes that govern stalk lodging resistance [3][4][5][6][7]22]. These key phenotypes are measured with the aid of mechanical phenotyping devices [24]. However, a method to properly account for plant weight when measuring stalk flexural stiffness and stalk bending strength has not been presented.…”