Soybean nutrition in an improved single-nutrient source hydroponic solution

Understanding the relationship between plant tissue nutrient concentrations, visual symptoms, and physiological responses is critical for diagnosing and managing nutrient deficiencies and toxicities. Hydroponic systems are effective in these studies as they offer precise control of nutrient availability, but isolating specific deficiencies can be difficult due to the use of dual-nutrient salts and their unintended interactions. To address this, a modified hydroponic solution using single-nutrient sources has been developed to induce individual mineral deficiencies. Soybean (Glycine max (L.) Merr.) was grown to maturity in environmentally controlled conditions using this solution. A full-nutrient positive control was compared to treatments deficient in nearly all essential macro- and micronutrients. Plants were assessed for visual symptoms, height, biomass, and tissue nutrient concentrations. The system successfully supported healthy growth in the control treatment and effectively induced deficiencies of nitrogen, calcium, magnesium, zinc, manganese, copper, and iron, with potential deficiencies of phosphorus, sulfur, and molybdenum. No clear deficiency symptoms were observed for potassium, boron, or chloride treatments. To improve system sensitivity, adjustments to N, K, S, Ca, B, and Cl concentrations are recommended. This single-nutrient-source hydroponic approach offers a refined tool for studying mineral nutrition in soybean and other crops, with applications for agronomists, breeders, and researchers aiming to improve nutrient diagnostics and management strategies.