Cost–Benefit Analysis of the Use of Brassinosteroid-like Substances to Enhance the Production Efficiency of Red Champagne Finger Lime under Commercial

Abstract

Red Champagne finger lime (Citrus australasica) is a tropical fruit originating from Australia. Its pulp consists of translucent vesicles resembling caviar, with a distinctive aromatic sour taste. It is well suited for premium markets and export, offering high economic potential, with prices ranging from approximately 800–2,000 THB per kilogram. However, production per unit area remains limited, and fruit quality is often inconsistent. Therefore, this study aimed to evaluate the cost–benefit of using brassinosteroid-like substances to enhance the production efficiency of Red Champagne finger lime under commercial conditions. The experiment was arranged in a Randomized Complete Block Design (RCBD) with four treatments based on different concentrations of brassinosteroid-like substances: 0 ppm (control), 0.25 ppm, 0.5 ppm, and 1 ppm. A finger lime plants were grown in cement rings and sprayed three times at different growth stages: post-pruning, flowering, and fruit-setting. Data were collected on the number of fruits per plant and fruit weight. The results were then analyzed for cost and return using the Benefit–Cost Ratio (BCR) method. The findings showed that all concentrations of brassinosteroid-like substances increased yield and production value compared to the control. The application at 1 ppm produced the best fruit quality and the highest benefit–cost ratio. Therefore, the use of brassinosteroid-like substances at a concentration of 1 ppm is economically viable and suitable for commercial production of Red Champagne finger lime.