Which element causes plants to grow rapidly and develop a dark green color?

• A. Potassium
• B. Phosphorus
• C. Calcium
• D. Nitrogen

Answer: (D)

Nitrogen fuels plant growth and chlorophyll formation. It is a major component of amino acids, the building blocks of proteins, which are essential for new tissue and enzyme activity that drives rapid growth. It is also a key part of chlorophyll, the pigment that gives leaves their green color; with adequate nitrogen, plants synthesize more chlorophyll, resulting in a deeper, darker green appearance.

Other nutrients play important roles too, but their primary effects aren’t the same for rapid leafy growth and that rich green color. Potassium supports water regulation and general metabolism; phosphorus is crucial for energy transfer and root development; calcium helps build cell walls and supports growth signals. When nitrogen is available in adequate amounts, leaves become lush and green, and overall growth accelerates because protein synthesis and chlorophyll production are amplified.