Impact of Varying Sewage Effluent Concentrations on Growth and Germination of Capsicum Seeds: A Comparative Study of Atarodo and Shombo Species

Abstract

Over the years, direct irrigation with untreated urban sewage has been found to negatively impact plant growth and yield. This study evaluated the effects of various concentrations of treated sewage effluent (0%, 25%, 50%, 75%, and 100% v/v, diluted with distilled water) on the germination and growth of two Capsicum species: Capsicum chinense (Atarodo) and Capsicum annuum (Shombo). A 2×5 factorial experiment was conducted using a completely randomized design (CRD) with three replicates. Parameters measured biweekly included plant height, number of leaves per plant, leaf area (up to the 12th week), germination percentage at 10 days, and days to seedling emergence. Sewage effluent was characterized for pH, electrical conductivity (EC), nitrogen (N), phosphorus (P), potassium (K), and heavy metals (Pb, Cd, Zn). Data were analyzed using analysis of variance (ANOVA), with significant means separated by the Least Significant Difference (LSD) test. Results showed significant differences in days to seedling emergence between species (P<0.001). Plant height differed significantly at weeks 2, 4, 6, and 12 (P<0.01), with marginal significance at week 10 (P<0.05). Leaf area and number of leaves per plant also varied significantly (P<0.001 and P<0.01, respectively). Germination percentage was not significantly affected by sewage effluent concentration, though 40% of treatment combinations achieved 50–70% germination success. Moderate effluent concentrations (25–50%) promoted early growth, while undiluted effluent (100%) reduced germination and growth due to high salinity and potential toxicity. These findings suggest that controlled use of treated sewage effluent can enhance Capsicum growth, but untreated sewage is detrimental