- A A naturally occurring soil extract that researchers collect, filter, and dilute before applying it to hydroponic growing systems
- B A defined nutrient solution containing all essential minerals in known concentrations, used to study mineral requirements and grow plants without soil
- C A pesticide and fungicide blend regularly applied to hydroponically grown plants to protect their developing root systems from insect pests and fungal infection
- D A hormone-supplemented growth medium developed mainly for propagating plant tissue cultures under sterile laboratory conditions
Correct answer: B. A defined nutrient solution containing all essential minerals in known concentrations, used to study mineral requirements and grow plants without soil
Explanation: Hoagland solution (developed by D.R. Hoagland) is a precisely defined aqueous solution containing all essential mineral nutrients. It is the standard medium for hydroponic experiments studying mineral nutrition, deficiency symptoms, and uptake mechanisms in plant physiology research.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.