<![CDATA[Abstract. Husen S, Iriany A, Garfansa MP, Andarista AP, Wahono W. 2026. Cocopeat-based substrate and fertilizer interaction for G0 potato minituber production. Asian J Agric 10 (2): g100216. https://doi.org/10.13057/asianjagric/g100216. G0 potato minituber production from rooted cuttings requires appropriate combinations of growing substrate and fertilization regime to support vegetative performance and minituber yield. This study evaluated the interaction between four cocopeat-based substrate compositions and two fertilization regimes on vegetative performance at 49 day after transplanting (DAT), yield components, and selected minituber size-class responses of potato (Solanum tuberosum) cv. Granola Kembang under screenhouse conditions. The experiment was arranged in a factorial randomized complete block design with three replications, resulting in 24 seedbeds as experimental units and 192 initially transplanted plants. Yield measurements were based on actual number of surviving and intact plants in each seedbed. The analyzed size classes were small tubers (<5 g) and 20-100 g tubers; therefore, the grading data represented selected size-class responses rather than a complete tuber-size distribution. The substrate-fertilizer interaction significantly affected vegetative variables at 49 DAT, minituber yield components, and selected size-class proportions. H4P2 had the highest numerical mean for plant height, although it was not significantly different from H4P1. H4P1 showed the highest numerical means for several canopy-related traits, but these values were not always significantly different from those under H4P2. H4P1 also showed the highest numerical means for individual tuber weight and tuber fresh weight plant-¹, whereas H3P2 had the highest numerical mean for tuber number plant-¹. Although H4P1 had the highest numerical proportion of 20-100 g tubers, this size class remained uncommon across all treatments. These numerical patterns suggest that treatment combinations associated with greater tuber number may differ from those associated with greater individual tuber weight and fresh yield. Under the tested conditions, substrate-fertilizer selection should therefore be aligned with the intended production target. However, the findings represent treatment-specific responses from one cultivar, season, location, and screenhouse environment and require further validation before broader recommendations are made.]]>
