Dynamics of Value Instability in Thai Durian An Empirical Analysis of Demand and Supply Shifts (2005–2023)

Abstract

      Durian has become a rapidly expanding agricultural export, particularly since 2015, with significant increases in cultivated area, output, and prices. However, most farmers remain price takers, which causes income to fluctuate according to changes in supply and demand. Prior studies have examined these issues within the framework of traditional market structures; however, such models fail to account for the volatility observed during the period of Thai durian's heavy export reliance on the People's Republic of China. This research aims to examine the level and causes of instability in the value of durian received by farmers. The study utilizes secondary time-series data comprising farm-gate prices, production volumes, and production values from 2005 to 2023 from the Office of Agricultural Economics and the Customs Department. The analysis applies the Instability Index in conjunction with the coefficient of determination (R²) to identify the underlying causes of value instability. The results reveal that during 2005-2014, the primary source of volatility in production value was primarily driven by shifts in the supply curve amidst relatively inelastic demand. Conversely, from 2015 to 2023, instability was predominantly driven by shifts in the demand curve coinciding with high supply elasticity. This shift reflects the adaptation of Thailand's durian industry in response to the influence of global markets, particularly China's rapidly growing market following the implementation of free trade agreements.
 
Article history: Received 19 December 2025       
                            Revised 17 March 2026      
                            Accepted 14 April 2026       
                            SIMILARITY INDEX = 2.41 %