Question

Which of the following is a plant hormone, applied for ripening of fruits and is permitted legally

• A. Auxin
• B. Cytokinin
• C. Papain
• D. Ethylene

Hint:

Ethylene gas is safe and legally approved for artificial ripening because it acts as a natural trigger for climacteric respiration in fruits. Always differentiate it from calcium carbide, which is strictly prohibited under food safety regulations.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Phytohormones (plant hormones) are chemical messengers that coordinate cellular activity and physiological processes in plants.
Fruit ripening is a complex developmental process that involves changes in color, texture, flavor, and aroma, primarily governed by gaseous phytohormones.

Step 2: Detailed Explanation:
Let us evaluate each of the given choices:
- Auxin: This hormone is primarily involved in cell elongation, apical dominance, and root initiation, rather than fruit ripening.
- Cytokinin: This hormone is responsible for cell division and delaying senescence in plant tissues.
- Papain: This is a proteolytic enzyme extracted from the raw papaya fruit, not a phytohormone.
- Ethylene: This is a gaseous plant hormone that naturally regulates senescent processes and fruit ripening in climacteric fruits.
- Legally, the controlled use of ethylene gas is permitted for the artificial ripening of fruits because it mimics the natural physiological ripening process without introducing toxic residues.
- Conversely, chemical agents like calcium carbide (which produces acetylene gas) are legally banned due to the presence of carcinogenic impurities such as arsenic and phosphorus hydrides.
Therefore, ethylene is the legally permitted phytohormone used for fruit ripening.

Step 3: Final Answer:
The legally permitted plant hormone used for the ripening of fruits is ethylene.