Assessing the role of variety renewal in enhancing agro-product regional public brand value: a case study of Gaizhou grapes.

Introduction: Analyzing the stability of agro-product regional public brands from the perspective of variety renewal can address the shortcomings of existing micro-level research. Using Gaizhou grapes in Liaoning Province, China, as a case study, this study examines the large-scale replacement of the traditional Kyoho grape with Shine Muscat and explores how variety renewal affects farmers' production and economic outcomes. Methods: Ordinary least squares (OLS), instrumental variable (IV), and quantile regression models were employed to estimate the effects of variety renewal on grape yield, income, and unit prices. The average value of variety renewal choices among other farmers in the same village was used as an instrumental variable to address potential endogeneity. Results: The results show that variety renewal reduces grape yield but significantly increases farmers' total income and unit prices. The IV estimates confirm the robustness of these findings. The quantile regression results reveal substantial heterogeneity in the effects of variety renewal across renewal patterns and different points of the yield, revenue, and unit price distributions. Full renewal is more likely to improve revenue and unit prices among farmers at higher revenue or quality levels, whereas its yield effects are less favorable among farmers with medium or lower yield levels. By contrast, partial renewal tends to generate weaker economic gains and may even reduce yield or revenue among farmers at medium outcome levels. Discussion: Rising production costs are an important factor contributing to the divergence between yield and income outcomes. Farmer training, improved access to information, enhanced online sales capability, stronger social learning, and greater social capital can mitigate yield losses associated with variety renewal to varying degrees, although their moderating effects differ across farm-scale groups. Overall, the findings indicate that variety renewal can enhance the value of regional agricultural products and support farmers' income growth, but its benefits depend on the degree of renewal, farm scale, and farmers' capabilities. This study provides empirical evidence for promoting agricultural brand upgrading and designing differentiated strategies for sustainable rural income growth.