Asian Journal of Agricultural and Horticultural Research

Urban farming systems based on substrate hydroponics require an optimal growing medium composition to ensure adequate aeration and water-holding capacity. This study was conducted to evaluate the effects of different proportions of cocopeat and rice husk biochar on flavonoid content, nitrogen (N) uptake, growth, and yield of mint (Mentha spp.) cultivated in a drip-irrigated substrate hydroponic system, as well as to identify the most suitable growing medium composition. The study was conducted in the Agronomy Laboratory Greenhouse, University of Bengkulu, Indonesia. A two-factor factorial experiment was arranged using a Completely Randomized Design (CRD). The first factor was mint variety (Spearmint, Chocolate Mint, and Apple Mint), while the second factor was the growing medium composition (80% cocopeat + 20% biochar, 60% cocopeat + 40% biochar, 40% cocopeat + 60% biochar, and 20% cocopeat + 80% biochar). The data were analyzed using analysis of variance (ANOVA) at the 5% significance level, followed by the Least Significant Difference (LSD) test at the 5% level. The results showed that mint variety and its interaction with growing medium composition significantly affected growth parameters. Apple mint showed the greatest stem diameter in 60% cocopeat + 40% biochar, the highest dry weight and nitrogen uptake in 20% cocopeat + 80% biochar, and the highest flavonoid content in 40% cocopeat + 60% biochar. Chocolate Mint produced the highest fresh and dry root weights in 80% cocopeat + 20% biochar. The interaction between mint variety and growing medium composition influenced several growth and yield parameters, indicating that the response to substrate composition depends on varietal characteristics.