Question

Synthetic seeds are produced by the encapsulation of somatic embryos with-

• A. Sodium acetate
• B. Sodium chloride
• C. Sodium nitrate
• D. Sodium alginate

Hint:

Remember the gelling reaction for synthetic seeds: {Sodium alginate + Calcium chloride \(\rightarrow\) Calcium alginate gel}. This is the key chemical principle behind the artificial seed coat.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Synthetic seeds (or artificial seeds) are produced in vitro to mimic the structure and function of true seeds. They consist of a somatic embryo (which acts as the plant embryo), an artificial endosperm (containing nutrients), and a protective outer coating. The question asks for the chemical used to create this outer coating.
Step 2: Detailed Explanation:
The encapsulation of somatic embryos requires a gelling agent that is non-toxic to the embryo, allows for nutrient and gas exchange, and provides protection.
Sodium alginate is the most widely used substance for this purpose. It is a natural polysaccharide derived from brown algae.
The process involves mixing somatic embryos with a sodium alginate solution and then dropping this mixture into a solution of calcium chloride (\(CaCl_2\)). The calcium ions cross-link the alginate polymers, forming a solid, insoluble gel of calcium alginate around the embryo. This bead acts as the artificial seed coat.
The other options are simple salts and are not gelling agents, so they cannot be used for encapsulation.
Step 3: Final Answer:
Somatic embryos are encapsulated with sodium alginate to produce synthetic seeds.