The contribution of pollinators varies among soybean cultivar traits

Abstract

Soybean is one of the most widely cultivated species worldwide. Empirical studies have shown that animal pollination can contribute between 0 and 50 % to soybean yields. However, the role of animal pollination in soybean production is often overlooked in management decisions. Understanding the factors driving variability in pollinator contribution can aid in developing effective management strategies. In this study, we experimentally assessed the contribution of both autonomous and animal pollination across nine widely cultivated soybean cultivars in the Chaco region of Argentina. Additionally, we explored whether specific traits of these cultivars could explain the observed variability in pollination contribution. We used field exclosure experiments to study cultivars that differed in flower color, genetic modifications, and maturity groups, and analyzed the variability in pollinators’ contributions across years and locations. We found that the overall reduction in production between open and bagged plants was, on average, 40 % (CI 25–51 %). The contribution of pollinators varied depending on flower color, maturity groups, and locations, but not across different years or genetic modifications. Cultivars with purple flowers showed greater differences between open and bagged plants compared to those with white flowers, indicating that flower color may influence the attractiveness of flowers to pollinators. Additionally, pollinators’ contribution varied across maturity groups, potentially due to the differential timing of the flowering affecting the local abundance of pollinators within the crop. Notably, the variable used to estimate pollinators’ contribution (i.e., seeds, pods, or yield) conditioned the results. Pollinators’ contribution can be highly variable, and traits associated with cultivars can help improve our understanding of such heterogeneity. Our results showed that the contribution of pollinators to soybean cultivars in the Chaco region of Argentina ranges from modest to high. This suggests that conserving pollinators and managing agricultural fields at plot and landscape scales can significantly impact soybean production.