Foliar Application of Gehna Super Bio-stimulant Enhances Growth, Yield, and Nutrient Uptake in Maize ( Zea mays L.) under South Indian Agroclimatic Conditions

Bio-stimulants represent a rapidly growing category of agronomic inputs that improve crop performance under both optimal and sub-optimal growing conditions. In this study, we evaluated the agronomic efficacy and economic viability of Gehna Super, a commercial plant bio-stimulant, applied as a foliar spray at four concentrations (2, 2.5, 3, and 5 ml L⁻¹ water) on maize (Zea mays L.) during Kharif 2022 at the University of Agricultural Sciences (UAS), GKVK, Bangalore. A randomized complete block design (RCBD) with five treatments replicated four times was employed. Gehna Super significantly enhanced plant height, leaf area index (LAI), total dry matter accumulation, cob length, kernel number, kernel yield, and N–P–K uptake compared to untreated control. Foliar spray at 5 ml L⁻¹ (T5) recorded the highest kernel yield (8,369 kg ha⁻¹; +36.9% over control) and total dry matter at harvest (463.16 g plant⁻¹). However, application at 3 ml L⁻¹ (T4) delivered the most favorable cost–benefit ratio (1:3.42). No phytotoxic effects were observed at any dose. Results indicate that Gehna Super at 2.5–3 ml L⁻¹ represents the optimal dose for maximizing economic returns in maize production under Eastern Dry Zone conditions of Karnataka, India.