Question

Requirement of nitrogen by plant is maximum at

• A. Initial
• B. Harvest
• C. Grand growth
• D. Flowering

Hint:

Maximum dry matter accumulation and structural synthesis occur during the grand growth phase of crops, making it the period of peak nutrient (N, P, K) demand.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Nitrogen is a primary macronutrient essential for plant development, as it is a fundamental constituent of amino acids, proteins, nucleic acids, and chlorophyll.
The uptake and requirement of nitrogen vary significantly across different physiological growth stages of a plant.
Detailed Explanation:
The life cycle of a crop can be divided into several developmental phases: initial (germination/seedling), vegetative (grand growth), reproductive (flowering/milking), and maturity (harvest).
During the Initial stage, the seedling is small and primarily relies on seed reserves, requiring minimal external nutrients.
During the Grand growth stage (active vegetative phase), the plant undergoes rapid cell division, leaf area expansion, stem elongation, and root development.
This is the period of peak biomass accumulation, where photosynthetic activity is maximized to build the structural framework of the plant.
Because proteins and chlorophyll are being synthesized at the highest rates during this phase, the plant's demand for nitrogen reaches its absolute maximum.
At the Flowering stage, nitrogen requirement begins to decline as the plant transitions from vegetative to reproductive growth, redirecting existing nitrogen reserves from leaves to developing seeds and fruits.
At Harvest, nutrient uptake ceases.

Step 2: Final Answer:
The plant's requirement for nitrogen is highest during the grand growth stage.