Abstract Detail

Physiology

Cook, Douglas [1], Julias, Margaret [1], Robertson, Daniel Jordan [1].

Forensic Analysis of Maize Stalk Lodging.

Stalk failure causes damage and often death of the plant. This topic is particularly relevant in agriculture, but the basic biomechanics behind the initiation and progression of stalk failure are poorly understood. This study describes a multi-modal failure analysis including forensic examination, image analysis, and structural engineering to gain new insights on stalk failure in maize. Maize stalk failure samples were carefully examined at several locations in North America and Africa during 2010, 2012, and 2014. To reduce the number of potential confounding factors, only stalks with no visible presence of disease or pest damage were included in this study. X-ray computed tomography was performed to obtain high-resolution geometric information of maize stalks at resolutions ranging from 78μm to 90μm per voxel. Customized computer code was developed to perform automatic analysis of the geometric features of stalk cross-section. Finally, tissue structures were investigated using stereo microscopy and scanning electron microscopy (SEM). Maize stalks were found to fail in just three modes, including tensile snapping, longitudinal splitting, and buckling/creasing (see Figure 1). This is the first detailed description of maize stalk failure modes in the scientific literature. Overall, 91% of all failed samples exhibited creasing failure. Creasing was commonly aligned with the major diameter of the stalk cross-section, and the predominant direction of failure was in the direction of the minor diameter of the maize stalk (Figure 1). Furthermore, 89% of creasing failures occur within 3 cm of a junction between adjacent sections of the stalk (Fig. 2). These results indicate strong connections between maize stalk physiology and failure. An analysis of maize stalk geometry (Fig. 3) revealed that extreme changes in stalk geometry occur at nodal junctions, possibly acting as a stress concentrator. SEM and CT imaging revealed that tissue delaminations (a phenomenon often occurred in composite materials) were frequently observed under the rind surface at the failure region (Fig. 5). As the intralayer delamination grows within the stalk, severity of failure increases, which ultimately lead to complete destruction of the stalk. The application of engineering failure analysis revealed distinct patterns in failure type, direction, and location. This new information resulted in a new model of stalk failure initation and progression.

1 - New York University Abu Dhabi, Division of Engineering, PO Box 903, New York, NY, 10276, USA

Keywords:
biomechanics
lodging
maize
Engineering.

Presentation Type: Oral Paper
Session: 9, Physiology
Location: 104/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 2:30 PM
Number: 9005
Abstract ID:917
Candidate for Awards:None