Individual and Combined Effects of Smoke-Water, Seaweed Extract, and Vermicompost Leachate on Maize Seedlings

Abstract

Modern agriculture’s reliance on synthetic agrochemicals has raised concerns over environmental sustainability, prompting exploration of eco-friendly alternatives such as natural biostimulants. This study evaluates the individual and combined effects of three biostimulants viz., smoke-water, seaweed extract (Kelpak), and vermicompost leachate on maize seed germination, seedling growth, hydrolytic enzymatic activity, and phytohormone profiles under light and dark conditions. Maize seeds were treated with various concentrations of each biostimulant and a combined formulation (CBS), and germination performance, α-amylase activity, and levels of selected phytohormones were assessed. Results showed that vermicompost leachate and the combined biostimulant treatment significantly enhanced root length and seedling vigour index, particularly under dark conditions. CBS treatment also elevated α-amylase activity under both light and dark regimes, indicating improved metabolic activation during germination. Phytohormone analysis revealed that CBS reduced levels of auxin, its conjugates, and abscisic acid under light, suggesting biostimulant-mediated hormonal modulation. No significant hormonal changes were observed under dark conditions, except for decreased oxIAA (2-oxindole-3-acetic acid) in CBS-treated seedlings. These findings demonstrate that biostimulant combinations can exert additive effects, enhancing early growth and metabolic activity while modulating hormone levels in maize seedlings. The study highlights the potential of integrated biostimulant strategies to support sustainable crop production.