Question

An orthodox seed is that which can tolerate
A. Dehydration and freezing.
B. Freezing but not dehydration.
C. Dehydration but not freezing.
D. High temperature.

Answer 1

Hint:These seeds have multiple applications due to their capacity of dormancy and survivability even through the extreme environmental conditions. Depending on the species, there are considerable amounts of complex-carbohydrate food reserves that ensure food availability during dormancy.

Complete answer: Orthodox seeds are those that can survive in either drying or freezing condition. Orthodox seeds survive to very low water contents. They can be safely presented in the freezer under conventional storage conditions.
Due to maturation drying, the embryo metabolism ceases to occur, making the seeds incapable of germination. These seeds cannot germinate even if the water content is ten to fifteen percent.
The germination occurs after the seed is fully hydrated. The germination occurs in three phases i.e. phase I, II, and III. It occurs based on the water content in the seeds.
With the aging of the seed, it undergoes several structural, biological, and genetic changes which may result in lessened seed viability.

So, the answer is option ‘A’ i.e. dehydration and freezing.

Additional information:
Orthodox seeds are seeds which can survive in either drying or freezing during ex-situ conservation, some of the examples are inclusive of peas, corn, tomatoes and can be dried to low humidity and frozen for long term storage. Thirty percent of the plant species worldwide have orthodox seeds. Orthodox seeds stored in a seed gene bank are dried up to five to six percent moisture content and placed in sealed containers stored at temperatures below minus eighteen degrees.

Note: Seeds are classified as orthodox seeds and recalcitrant seeds. The orthodox seeds can tolerate dehydration and freezing whereas recalcitrant seeds cannot. Germination in both occurs based on the water content in the seeds.