Valorization of Rice Wash Wastewater as a Circular Bio-Resource for Seed Priming: Enhancing Germination and Seedling Vigor in Waxy Corn and Papaya

Waxy corn and papaya are high-value, nutrient-dense crops in the Philippines, yet farmer-kept and heirloom seeds often exhibit delayed and uneven germination. This study situates rice wash (RW), an underutilized household wastewater, within a circular economy framework by evaluating its potential as a recycled bio-resource for seed priming. RW derived from different rice types (white, red, black, and brown) was characterized for pH, electrical conductivity (EC), total dissolved solids (TDS), and bioactive compounds including flavonoids, phenolics, tannins, and saponins. Seeds were primed through 12-hour soaking, air-dried, and germinated using the top-of-paper method following ISTA protocols. Germination rate (GR), vigor index (VI), and seedling dry weight (SDW) were assessed under a Completely Randomized Design with three replications and analyzed using ANOVA and LSD at α = 0.05.

Results showed significant variation (p=0.00) in RW physicochemical properties across rice types, reflecting differences in resource recovery potential. All RW samples contained phenolic compounds, while saponins were detected only in brown rice wash. White and red RW significantly enhanced germination, promoting faster and more uniform seed emergence, although biomass responses were crop-specific. These findings demonstrate that rice wash can be effectively valorized as a low-cost, eco-friendly biostimulant, transforming household wastewater into a functional agricultural input. This approach supports decentralized resource recovery, reduces liquid waste discharge, and advances circular economy strategies in sustainable crop production systems.