Question

Most commonly used chemicals to break dormancy in seeds requiring light (Ex. Oats, Lettuce, Gladiolus etc.) are:
(A). Potassium nitrate
(B). Kinetin
(C). Thiourea
(D). NAA
Choose the correct answer from the options given below:

• A. (A), (B), (C) and (D)
• B. (B), (C) and (D) only.
• C. (B) and (D) only.
• D. (A) and (C) only.

Hint:

In seed testing laboratories (ISTA guidelines), a $0.2\%$ solution of Potassium Nitrate ($\text{KNO}_3$) is the standard chemical treatment used to break dormancy in a wide range of agricultural seeds.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Seed dormancy is a physiological state that prevents germination even under favorable environmental conditions.
Various chemical treatments are used to break dormancy in agricultural and horticultural practices.

Step 2: Detailed Explanation:
Light-sensitive seeds, such as those of lettuce and wild oats, require specific signals to initiate germination.
1. Potassium nitrate ($\text{KNO}_3$) is a widely used chemical to break seed dormancy.
It acts as a nitrogen source and interacts with light-sensing pathways to stimulate germination.
2. Thiourea ($\text{CS(NH}_2)_2$) is another compound used to break seed dormancy, particularly in seeds that show thermodormancy or require light.
It can substitute for the light requirement in photoblastic seeds.
Auxins like NAA and cytokinins like Kinetin are plant hormones but are not the primary, most commonly used chemical compounds for breaking this specific type of dormancy in agricultural practice.
Thus, the most common chemical agents used are Potassium nitrate and Thiourea.

Step 3: Final Answer:
The correct option is (A) and (C) only.