Global market signaling in emerging economies: a hierarchical framework for low-emission agricultural labeling—evidence from Vietnam

Sustainability labeling has emerged as a key signaling mechanism in agri-food systems, yet its effectiveness in emerging economies remains unclear. Prior research assumed signal homogeneity, treating labels as equivalent instruments differentiated by environmental content rather than institutional architecture. This study examines whether low-emission labeling functions as a credible signal where price sensitivity, limited awareness, and institutional trust constraints prevail, conceptualizing it as a credence attribute dependent on complementary sustainability signals. A discrete choice experiment (n = 1,118) in Vietnam with latent class choice modeling identifies two segments: price-sensitive (46.7%) and eco-conscious (53.3%), with distinct valuation patterns. GAP certification, circular farming, and biodegradable packaging generate significant willingness to pay, whereas low-emission attributes exhibit limited traction and produce willingness-to-pay penalties at sub-baseline levels. These penalties reflect an institutional credibility deficit whereby environmentally literate consumers apply demanding verification standards to unverifiable claims, consistent with central-route processing under absent institutional anchoring, a novel boundary condition on the Elaboration Likelihood Model in sustainability marketing. Three theoretical contributions emerge: the Hierarchical Signaling Framework links verifiability to label effectiveness; the Segmented Adoption Model reveals non-monotonic literacy-valuation dynamics under weak verification; and the credibility floor defines minimum verification for positive signal valuation, suggesting low-emission claims require sustainability bundling.