Agronomic and Pathological Responses of Shallots to Trichoderma harzianum Secondary Metabolites in Pot Experiments with Various Seedling Numbers

Shallots (Allium ascalonicum L.) are a major horticultural commodity in Indonesia with high economic value.This study aimed to evaluate the effectiveness of secondary metabolites produced by Trichoderma harzianum at different concentrations under various planting densities in shallot cultivation.The pot experiment employed a factorial completely randomized design consisting of two factors: secondary metabolite concentration (0%, 5%, 10%, and 15%) and planting density (1, 2, or 3 seedlings per pot).Agronomic parameters included plant height, number of bulbs per plant, bulb weight, total bulb weight per plant, and bulb diameter, while the pathological response was measured as anthracnose disease severity.Application of a 5% concentration of secondary metabolites synthesized by T. harzianum significantly increased plant height (by 16.08%), number of bulbs per plant (by 45.082%), and bulb diameter (by 24.21%).Additionally, anthracnose disease severity decreased by up to 25.57%.Higher concentrations Shallots are a major horticultural commodity in Indonesia with high economic value. of secondary metabolites (10% and 15%) did not result in significant differences compared with the 5% treatment.