Question

Artificial ripening of fruits is caused by the treatment of (a) \(\mid \mathrm{AA}\) (b) \(\mathrm{NAA}\) (c) ethylene (d) kinetin.

Short answer

The chemical used for artificial ripening of fruits is (c) ethylene.

Step-by-step solution

Understanding the Exercise

The exercise asks to identify the chemical that causes artificial ripening of fruits. The options are (a) AA, (b) NAA, (c) ethylene, and (d) kinetin. To solve this, we must know which of these chemicals is commonly used to ripen fruits artificially.

Identifying the Ripening Agent

Research in plant physiology indicates that ethylene is a natural plant hormone involved in the ripening of fruits. While other options like AA (auxin-like), NAA (synthetic auxin), and kinetin (a cytokinin) are associated with plant growth and development, it is ethylene that is known to be widely used for the artificial ripening process.

Choosing the Correct Answer

Based on the role of ethylene in the ripening of fruits, we can conclude that option (c) ethylene is the correct answer.

Key concepts

Ethylene

Ethylene is a small hydrocarbon gas and is one of the most widely studied plant hormones known for its role in plant biology from cell growth to aging. In the context of fruit ripening, ethylene acts as a key regulator, signaling the biochemical processes that lead to the changes in fruit texture, color, and flavor.

Commercially, ethylene is used to initiate the ripening process in a controlled manner, especially for fruits that are transported over long distances while unripe to prevent damage. Once the fruit reaches its destination, ethylene treatment can induce ripening, so it becomes ready for consumption at the right time. Ethylene's perception by the plant triggers a cascade of gene activation, leading to the softening of fruit, degradation of chlorophyll, increase in sugar content, and enhancement of flavor compounds.

Understanding the role of ethylene not only helps in post-harvest management of fruits but also sheds light on the broader aspects of plant development and senescence.

Plant Hormones

Plant hormones, also referred to as phytohormones, are signal molecules produced within plants that occur in extremely low concentrations and have profound effects on plant growth, development, and response to stimuli. There are several groups of plant hormones, each with their own unique roles:

• Auxins (like IAA and NAA) are primarily involved in cell elongation, differentiation, and division.
• Cytokinins (such as kinetin) promote cell division and can delay tissue aging.
• Gibberellins are important for stem elongation and seed germination.
• Abscisic acid plays a key role in seed dormancy and stress responses.
• Ethylene, which is unique as it's a gaseous hormone, and as mentioned earlier, is crucial for fruit ripening and senescence in plants.

Recognizing these functions not only assists in agricultural applications but also deepens our comprehension of plant ecology and physiology.

Fruit Ripening Process

The fruit ripening process is a transformation period where fruits develop their desirable qualities like sweetness, color, and better texture, making them palatable and ready to eat. It's a complex sequence that involves biochemical, physiological, and molecular changes regulated by plant hormones, among which ethylene is pivotal.

Ripening includes the softening of the fruit, which occurs due to the breakdown of cell walls; the starches converting into sugars, which increases sweetness; the development of volatile compounds contributing to the aroma and the breakdown of green pigments, allowing the fruit to acquire its ripe color.

Artificial Ripening

By understanding the natural ripening process, scientists have developed methods to artificially induce ripening by exposing fruits to ethylene gas. This practice can be beneficial for synchronizing ripening for market availability, but it's crucial to monitor and control the application closely to ensure food safety and avoid the use of harmful ripening agents.