Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Calyx splitting is a major disorder of carnation and in this, calyx split when the flowers start to open.
Reason (R) : This is attributed to various factors such as over feeding, varietal character, high temperature, a sharp drop in night temperature, a low nitrogen level or boron deficiency.
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
• B. Both (A) and (R) are correct but (R) is NOT the correct explanation of (A).
• C. (A) is correct but (R) is not correct.
• D. (A) is not correct but (R) is correct.

Hint:

To prevent calyx splitting in greenhouses:
- Maintain stable, uniform day and night temperatures.
- Apply balanced nutrition (especially boron and nitrogen).
- Use plastic calyx bands or rings to support the buds of susceptible varieties during opening.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Calyx splitting is a major physiological disorder in commercial carnation (*Dianthus caryophyllus*) cultivation, particularly affecting standard varieties grown in greenhouse environments.

Step 2: Detailed Explanation:
Let us analyze the assertion and reason:
Assertion (A): "Calyx splitting is a major disorder of carnation and in this, calyx split when the flowers start to open."
This statement is correct.
The calyx is a protective, cup-like outer envelope of the flower.
As the flower bud begins to open, the rapid expansion of the inner petals can put too much pressure on the calyx, causing it to split down the side.
This allows the petals to spill out unevenly, ruining the flower's symmetrical shape and reducing its market value.
Reason (R): "This is attributed to various factors such as over feeding, varietal character, high temperature, a sharp drop in night temperature, a low nitrogen level or boron deficiency."
This statement is correct.
The disorder is caused by a mix of genetic, nutritional, and environmental factors:
- Sudden drops in night temperature (below $10^{\circ}\text{C}$) cause the flower to produce extra petals inside the bud, putting more pressure on the calyx.
- Fluctuations in fertilizer levels (over-feeding), low nitrogen, and micronutrient deficiencies (specifically boron deficiency, which weakens cell walls) make the calyx more brittle and prone to splitting.
- Some varieties are also genetically more susceptible to the disorder than others.
These environmental and nutritional factors directly explain the physical splitting described in (A).
Thus, (R) is the correct explanation of (A).

Step 3: Final Answer:
Both (A) and (R) are correct, and (R) is the correct explanation of (A).
This matches Option (A).