Optimizing the Application Frequency of Trehalose Foliar Fertilizer for Off-Season Tomato (Solanum lycopersicum L.) Production in Bacnotan, La Union

This study evaluated the optimal frequency of trehalose foliar fertilizer application for enhancing the growth, yield, and economic viability of a solanaceous crop cultivated under protected conditions in Bacnotan, La Union. A randomized complete block design was used with four application frequencies: once, twice, thrice, and four times, using a fixed concentration of 2 tablespoons per 16 liters of water. Results showed no significant effects on flowering time, vegetative growth, total yield per area, or pest and disease occurrence. However, a statistically significant increase was observed in the number of fruits per plant, marketable yield, and harvest frequency under thrice application. No further benefit was gained from four applications, indicating a threshold beyond which efficiency declines. These findings support the use of moderate foliar treatment frequency to improve crop productivity while reducing input costs. Further validation under different agroecological conditions is recommended.