31. Following are certain statements regarding seed development in plants:
A. During final phase of development embryo’s of “orthodox” seeds became tolerant to desiccation, dehydrate losing up to 90% of water
B. Dormant seeds will germinate upon rehydration while quiescent seeds require additional treatments or signals for the germination
C. Precocious germination is germination of seeds without passing through the normal quiescent and/or dormant stage of development
D. Abscisic acid is known to inhibit precocious germination
Which one of the following combinations is correct?
(1) A, B and C                                                          (2) A, B and D
(3) B, C and D                                                         (4) A, C and D

The correct combination of statements regarding seed development in plants is:

(1) A, B and C

Explanation:

• (A) During the final phase of development, embryos of “orthodox” seeds become tolerant to desiccation and dehydrate losing up to 90% of water — Correct. Orthodox seeds undergo desiccation tolerance acquisition, allowing them to survive extreme drying and remain viable for long periods.​

• (B) Dormant seeds will germinate upon rehydration while quiescent seeds require additional treatments or signals for the germination — Correct. Dormant seeds have physiological dormancy barriers and need signals; quiescent seeds germinate readily when water is available.​

• (C) Precocious germination is germination of seeds without passing through the normal quiescent and/or dormant stage of development — Correct. It refers to premature germination occurring during seed maturation or on the mother plant.​

• (D) Abscisic acid is known to inhibit precocious germination — Incorrect. ABA promotes seed dormancy and inhibits precocious germination.​

Introduction

Seed development culminates in the formation of mature, viable seeds capable of surviving adverse conditions before germination. Understanding the phases of seed desiccation tolerance, dormancy status, and precocious germination offers insights into seed biology, ecology, and agriculture.

Desiccation Tolerance in Orthodox Seeds

• Orthodox seeds lose up to 90% of their water during maturation, entering a metabolically quiescent, dry state that grants longevity and viability.​

• This physiological adaptation involves accumulation of protective proteins and metabolites governed partially by abscisic acid signaling.​

Dormancy and Quiescence in Seeds

• Dormant seeds possess physiological or morphological barriers preventing immediate germination post hydration, requiring external or internal cues.​

• Quiescent seeds lack dormancy mechanisms and will germinate upon hydration under favorable conditions.​

Precocious Germination

• Occurs when seeds germinate prematurely without undergoing dormancy or quiescence, often due to environmental factors or hormonal imbalances.​

• It deviates from the typical seed maturation process and can impact seed viability and plant propagation.​

Role of Abscisic Acid (ABA)

• Although ABA inhibits germination to maintain dormancy, it indirectly prevents precocious germination by promoting seed maturation and desiccation tolerance.​

• Statement (D) incorrectly states that ABA inhibits precocious germination explicitly; it regulates dormancy maintenance but precocious germination may occur due to failed ABA signaling.​

Summary Table: Seed Development Statements

Conclusion

Statements A, B, and C accurately describe seed development phases in plants, while statement D is imprecise regarding the role of ABA in inhibiting precocious germination.