Question

The essentiality of nitrogen for plant growth was discovered by

• A. Priestley
• B. C. Sprengel
• C. Theodore de Saussure
• D. Arnon and Stout

Hint:

Theodore de Saussure used quantitative chemical methods to prove that plants obtain their mineral elements and nitrogen from the soil, not the air.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The history of plant nutrition includes several key scientific discoveries that identified the essential elements required for plant growth and development.
Detailed Explanation:
Let us review the contributions of each scientist listed in the options:
- Priestley (1771): Discovered that plants restore the air "injured" by burning candles or breathing animals, paving the way for the discovery of oxygen and photosynthesis.
- C. Sprengel (1828): Formulated the basic concept of the "Law of the Minimum" (later popularized by Justus von Liebig), which states that plant growth is limited by the scarcest nutrient resource.
- Arnon and Stout (1939): Proposed the three criteria of essentiality for plant nutrients, which are still used to classify essential elements today.
- Theodore de Saussure (1804): Conducted quantitative chemical experiments demonstrating that plants absorb carbon dioxide and water to assimilate carbon, and that they absorb essential mineral elements and nitrogen from the soil rather than the atmosphere. His work established that nitrogen is an essential element absorbed through the root system for plant growth.

Step 2: Final Answer:
The essentiality of nitrogen for plant growth was demonstrated by Theodore de Saussure.