Question

Seeds that are killed by drying and freezing temperature are called as

• A. Recalcitrant seeds
• B. Orthodox seeds
• C. Sensitive seeds
• D. Immature seeds

Answer 1

Answer: (A)

Recalcitrant seeds

Recalcitrant seeds (subsequently known as unorthodox seeds) are seeds that do not survive drying and freezing during ex-situ conservation and visa versa. By and large, these seeds cannot resist the effects of drying or temperatures less than 10 degree C; thus, they cannot be stored for long periods like orthodox seeds because they can lose their viability. Plants that produce recalcitrant seeds include avocado, mango, mangosteen, lychee, cocoa, rubber tree, some horticultural trees, and several plants used in traditional medicine, such as, species of Virola and Pentaclethra. The two main mechanisms of action of damage to recalcitrant seeds are desiccation effect on the intracellular structures and the effect of metabolic damage from the formation of toxic chemicals such as free radicals.
Orthodox seeds are those which are capable of withstanding reduction in moisture (upto 5%) and prolonged exposure to low temperature(10 degree C to20 degree C) e.g., cereals and legumes.

Thus, the correct answer is option A.