Association of Selected Plant Traits with Lodging of Four Determinate Soybean Cultivars

Abstract

Lodging of soybean [Gfycine max (L.) Merr.] frequently reduces seed yield and quality, especially in high‐yield environments. Breeding for resistance to plant lodging is high priority in most soybean programs, but information is limited on effective techniques to evaluate this trait. This study was conducted to measure the association of selected plant traits with lodging score at maturity. Field and laboratory experiments were conducted to evaluate lodging of four determinate Maturity Group V cultivars: Essex, Narow, Forrest, and Mack. Based on four environments, Essex had the lowest lodging score (least lodging), Mack the highest score, and Narow and Forrest were intermediate. Lodging score was significantly (P ≤ 0.01) correlated with plant height at three reproductive stages, R4, R6, and R8, but not at the V8 stage. Length and diameter of basal and centrally located internodes generally were not significantly (P > 0.05) associated with lodging score. Bark percentage at Stage R8 was negatively correlated with lodging score. In contrast, there was a significant (P ≤ 0.05) positive association between lodging score and xylem width and xylem percentage at Stages R6 and R8. The capacity of the plant to recover a more vertical position, measured by the angle of the stem from horizontal after bending for 4 s at R6 and R8, was negatively correlated with lodging score at maturity. Stem stiffness was measured in the laboratory by the distance a specific weight bent the stem and by the weight required to bend the stem a specific distance. Stem stiffness generally was not associated with resistance to lodging. Results indicate that plant resiliency rather than stem stiffness is associated with lodging resistance in these soybean cultivars. Plant height and bark and xylem percentage also were associated with plant lodging and may be of value in breeding for this trait.