The Overlooked Biomechanical Role of the Clasping Leaf Sheath in Wheat Stalk Lodging

Abstract

The biomechanical role of the clasping leaf sheath in stalk lodging events has been historically understudied. Results from this study indicate that in some instances the leaf sheath plays an even larger role in reinforcing wheat against stalk lodging than the stem itself. Interestingly, it appears the leaf sheath does not resist bending loads by merely adding more material to the stalk (i.e., increasing the effective diameter). The radial preload of the leaf sheath on the stem, the friction between the sheath and the stem and several other complex biomechanical factors may contribute to increasing the stalk bending strength and stalk flexural rigidity of wheat. Results demonstrated that removal of the leaf sheath induces alternate failure patterns in wheat stalks. In summary the biomechanical role of the leaf sheath is complex and has yet to be fully elucidated. Many future studies are needed to develop high throughput phenotyping methodologies and to determine the genetic underpinnings of the clasping leaf sheath and its relation to stalk lodging resistance. Research in this area is expected to improve the lodging resistance of wheat.

Identification of QTL underlying the main stem related traits in a doubled haploid barley population

“…Stem strength can be affected by various factors. The leaf sheath could provide great physical support ( Cornwall et al., 2021 ). Lodging resistance is usually related to stem diameter.…”

“…Based on stalk characteristics and lodging factors, a lodging index was proposed to measure the lodging trait (Islam et al, 2007;Li et al, 2017), thus, the lodging index becomes a comprehensive trait composed of many single traits. Moreover, some studies have indicated that leaf sheaths and vascular bundles are also crucial contributing factors to lodging (Wu and Ma, 2020;Cornwall et al, 2021). Lin et al (2005) indicated that a lower pith diameter/stem diameter ratio can improve stem strength.…”

The Effect of Testing Rate on Biomechanical Measurements Related to Stalk Lodging

“…Three-point bending experiments were performed on maize and wheat at multiple displacement rates to understand the effect of rate on exural stiffness and bending strength measurements. Wheat samples were tested both with and without the leaf sheath as the leaf sheath has a signi cant effect on the biomechanical response of wheat stems [39]. Rind puncture experiments were performed on maize stalks at multiple displacement rates to understand the effect of displacement rate on puncture force and integrated puncture score measurements [34].…”

“…The wheat did not need to be stored in the greenhouse prior to being placed in the lab to prevent fungal growth. In addition, the leaf sheaths were not removed from the wheat plants prior to storing them in the laboratory as the leaf sheath signi cantly in uences the bending stiffness and bending strength of wheat stems [39].…”

The Crop Clamp – A non-destructive electromechanical pinch test to evaluate stalk lodging resistance

“…It is therefore desirable to breed for maize varieties that are more resistant to stalk lodging [3][4][5]. It has been well established that stalk lodging in maize is related to stalk structural features [2,3,[6][7][8][9][10][11][12][13][14]. Obtaining accurate measurements of these structural features aids agronomists in selecting lodging-resistant maize varieties for breeding [3,[15][16][17][18].…”