Lodging dynamics and seed yield for two soybean genotypes with contrasting lodging-susceptibility

Abstract

Plant lodging prior to harvest is a potential yield limiting factor in soybean production, especially in high-yield, irrigated environments. The mechanism(s) through which lodging limits yield, and the benefits of lodging resistant genotypes are not clearly understood. The objectives of this study were (i) to measure temporal lodging dynamics of two soybean genotypes with contrasting lodging resistance under irrigated conditions, and (ii) to quantify the effect of lodging on soybean yield and yield components. To address these objectives, ACA530 (lodging susceptible) and SRM5001 (lodging resistant) in combinations with two lodging treatments (unstaked and staked plots to reduce lodging) were evaluated during two years under irrigated conditions. We evaluated temporal lodging dynamics by recording 3D coordinates of all nodes per plant and estimated a quantitative lodging ratio. The lodging resistant genotype did not lodge either year while the susceptible genotype, between R1-R3 in year 2 and between R3-R5 in year 1. While stakes within the canopy reduced lodging of the susceptible genotype there was not full control, and this was specifically noted in year 2. The lodging resistant genotype produced a yield 38 % greater than the lodging susceptible genotype through increased seed number (p<0.001) and total biomass at maturity (p<0.001). Interestingly, while the staked treatment reduced lodging of the susceptible genotype there was no yield improvement suggesting that the reduced yield of this genotype is not mechanistically associated with lodging. In this limited dataset, the two important contributions are: i) a methodology to manipulate and measure soybean lodging and, ii) that yield formation is not affected negatively when lodging occurs.