Influence of Irrigation Water Sources on Growth Performance, Nutritional Composition, and Heavy Metal Accumulation of Amaranthus hybridus L.

Water scarcity and rapid urbanization have increased the use of alternative water sources for vegetable production. The growth, nutritional components, and heavy metal deposition of Amaranthus hybridus grown in Daki-Biu District, Abuja, Nigeria, were assessed in this study in relation to several irrigation water sources. A pot experiment was conducted using a completely randomized design with four treatments: tap water (control, T1), well water (T2), stream water (T3), and wastewater (T4), with each treatment replicated three times. Irrigation water quality, growth parameters (plant height, number of leaves, leaf area and fresh weight), proximate composition, and heavy metal concentrations were determined using standard laboratory procedures. Data were subjected to analysis of variance (ANOVA) at a 5% significance level. T4 had the highest electrical conductivity (1268 µS/cm⁻¹) and potassium level, while Cadmium and lead exceeded WHO safety limits. The results showed significant differences (p < 0.01) among treatments. Plants irrigated with T4 recorded the greatest plant height (58.2 cm), fresh weight (51.0g plant⁻¹), and number of leaves (24.3); however, leaf area was high in plants irrigated with T1 (49.3 cm²). Crude protein content was highest in T2 (6.09%) and T4 (5.84%), while carbohydrate content was higher under T1 treatment. Heavy metal analysis showed high concentrations of cadmium, lead, and chromium across all treatments, with the highest in T4, exceeding recommended safety limits for vegetable consumption. The findings showed that T4 treatment can enhance the growth, yield, and nutritional quality of Amaranthus hybridus but poses significant food safety risks due to heavy metal accumulation.