Q.Why do you think the zygote is dormant for sometime in a fertilised ovule?

Seed Dormancy: A Survival Strategy in Plants

Imagine you buy a packet of seeds for your garden. You plant them, water them, and wait. Some sprout in a few days. Others sit in the soil for weeks or months before they finally wake up. That delay is not laziness — it is a deliberate, built-in pause called seed dormancy.

The Everyday Intuition

Think of a seed as a tiny, sleeping baby plant wrapped in a protective coat. If every seed sprouted the moment it fell from the parent plant, what would happen? A seed that lands in the middle of a dry summer would germinate, then die from lack of water. A seed that falls in autumn would sprout just before winter frost kills the tender shoot. Nature avoids this disaster by giving seeds a "pause button." That pause is seed dormancy.

The Precise Meaning

In biology, seed dormancy is a state in which a viable seed (one that is alive and capable of growing) does not germinate even when all external conditions — water, oxygen, temperature, light — appear favourable. The seed is not dead; it is simply refusing to wake up until some internal or external "lock" is released.

Why Does Dormancy Exist?

The purpose is survival. A seed that germinates at the wrong time will die. Dormancy ensures that germination happens only when the environment is likely to support the seedling's growth. Here are the main reasons:

• To survive unfavourable seasons — Seeds of many temperate plants remain dormant through winter and germinate only in spring.
• To avoid competition — Some seeds lie dormant in the soil for years, waiting for a fire, flood, or clearing that removes competing plants.
• To spread germination over time — Not all seeds from the same plant germinate in the same year. This "bet-hedging" ensures that if one year is disastrous, some seeds remain for the next.

Types of Seed Dormancy (as per NCERT)

The NCERT textbook classifies dormancy into two broad categories:

1. Innate (Primary) Dormancy

The seed is born dormant. It will not germinate even under ideal conditions until a specific trigger occurs. This is further divided into:

• Physical dormancy — The seed coat is hard and impermeable to water or oxygen. The seed cannot absorb water to start germination. Example: seeds of many legumes (peas, beans).
• Physiological dormancy — The embryo itself is immature or contains chemical inhibitors that block germination. Example: seeds of apple, peach, which need a period of cold (stratification) before they can sprout.

2. Induced (Secondary) Dormancy

A seed that was initially capable of germination becomes dormant again because of unfavourable conditions. For example, if a seed starts to germinate but then faces extreme heat or drought, it may re-enter dormancy.

How Is Dormancy Broken?

Nature has evolved several mechanisms to "wake up" dormant seeds: