Row spacing, seeding depth, seeding rate, and trinexapac-ethyl effects on oat yield and lodging

Lodging can reduce the yield and quality of oats (Avena sativa L.). Root lodging, as opposed to stem lodging, is the predominant form of lodging in oats. Therefore, identifying management practices that enhance root lodging resistance should be prioritized. The objective of this study was to investigate the effect of four management practices on oat grain yield, yield components, grain quality, observed lodging, and plant traits that contribute to root lodging resistance. Row spacing and seeding depth were tested in three oat cultivars across two environments in Ontario, Canada. Seeding rate and the application of the plant growth regulator trinexapac-ethyl (TE) at different nitrogen (N) fertilizer rates were tested in two-to-three oat cultivars across four environments. Lodging occurred naturally in all environments, with root lodging always occurring, sometimes in combination with stem lodging. Under high lodging pressure, shallow seeding increased lodging. Similarly, lodging increased with greater seeding rates when lodging pressure was high. Reducing row spacing had no effect on lodging but was the only management practice to consistently increase grain yield. TE reduced lodging in some environments, especially as N rates increased. Root plate spread, root plate depth, and root safety factor were minimally affected by the management practices studied and had complex interactions with genotype and environment. Among the measured crop traits, plant height had the strongest and most consistent relationship to observed lodging.