Effects of Filter Cake from Sugar Mill Utilization As an Alternative Growing Medium on Growth Performance, Yield, and Economic Profitability of Melon in Soilless Culture

This study investigated the effects of filter cake as an alternative growing medium on the growth, yield, and economic profitability of melon in a soilless system. The greenhouse experiment followed a completely randomized design with three treatments: 100% coconut coir (control), 100% filter cake, and 50% filter cake + 50% coconut coir, each with three replications (90 plants in total). Growth was recorded weekly from 7 to 63 days after transplanting (DAS), and fruit quality was assessed at harvest. The 100% filter cake treatment significantly enhanced vegetative growth (P<0.05), producing the highest plant height (95.40 cm), number of nodes (13.30), number of leaves (13.30), and leaf width (19.30 cm) at 21 DAS. Although fruit quality parameters did not differ significantly (P>0.05), 100% filter cake tended to yield superior fruit weight (1.16 kg) and total soluble solids (16.69 °Brix). Economic analysis revealed that 100% filter cake provided the highest gross profit (82.70 THB plant⁻¹), return on growing media cost (55.68 times), yield per unit investment (0.464 kg THB⁻¹), and maximum investment efficiency (2.46 times per crop cycle). Its economic advantage resulted from the lowest growing-medium cost (2.50 THB plant⁻¹) while maintaining good yield and quality. Filter cake shows high potential as a cost-effective and sustainable alternative to coconut coir in soilless melon production. The results apply to the ‘Khaitongkham Melon’ variety during one growing season; further studies across varieties and seasons are recommended.