Differential responses of soybean genotypes to off‐target dicamba damage

Abstract

AbstractSince the commercialization and widespread adoption of dicamba‐tolerant (DT) soybean cultivars across the United States, numerous cases of off‐target damage to non‐DT soybean have been reported. Soybean is naturally highly sensitive to dicamba, a synthetic auxin herbicide. Previous studies have focused on understanding the impact of growth stage, dosage, frequency, and duration of dicamba exposure on the severity of symptomology and yield loss. To date, little research has investigated the effect of genetic components in the observed responses. Therefore, this study was conducted to estimate yield losses caused by prolonged off‐target dicamba exposure and to identify genotypes with varying responses to off‐target damage. A total of 553 soybean genotypes derived from 239 unique biparental populations were evaluated in nine environments over 3 yr. A yield penalty of 8.8% was observed for every increment in damage score on a 1–4 scale with losses as high as 40%. Although the interaction between damage and maturity group (MG) significantly affected yield, genotypes showing the most tolerance had similar yields independent of their MG. This indicated that natural tolerance to off‐target dicamba may be conferred by physiological mechanisms other than the length of the recovery window. Given the widespread adoption of DT systems and potential yield losses in non‐DT soybean genotypes, identification of non‐DT soybean genotypes with higher tolerance to off‐target dicamba may sustain and improve the production of other non‐DT herbicide soybean production systems, including the niche markets of organic and conventional soybean.