Methods of breaking seed dormancy

Introduction

Dormancy occurs when there is a lack of germination in seeds or tubers despite the presence of the necessary conditions (temperature, humidity, oxygen, and light). Dormancy is caused by hard seed coat impermeability or a lack of supply and activity of enzymes required for germination (internal dormancy). 

Dormancy is a significant factor that limits production in many field crops. To overcome dormancy, the organic material (seeds/tubers) is subjected to a number of physical and chemical pretreatments. Physical and physiological dormancy can coexist in some plants, making it difficult to provide high-frequency, healthy seedling growth, as the formation of healthy seedlings from organic material (seeds/tubers) sown is a requirement for plant production. 

What is seed dormancy?

Seed dormancy is an evolutionary adaptation that prevents seeds from germinating in unsuitable ecological conditions, which would normally result in a low likelihood of seedling survival. Dormant seeds do not germinate within a specified time frame when a combination of environmental factors that are normally conducive to non-dormant seed germination is present. 

Delayed germination is an important function of seed dormancy because it allows dispersal and prevents all seeds from germinating at the same time. The staggered germination protects some seeds and seedlings from damage or death caused by short periods of bad weather or transient herbivores; it also allows some seeds to germinate when competition for light and water from other plants is less intense.

Seed quiescence is a type of delayed seed germination that differs from true seed dormancy in that it occurs when a seed fails to germinate because the external environmental conditions are too dry, warm, or cold for germination.

Methods of breaking seed dormancy

There are several ways to break the hard seed coat in this method, including:

• Seeds are manually rubbed on sand paper. It is important to avoid damaging the seed’s axis when rubbing. Subabul and green gramme

• When the seed coat is overly hard. Because of its woody nature, the seed coat must be completely removed by breaking it. Rubber seed (Havea app) India teak wood seed

• Soaking treatment: Soaking hard seed coat for 1 to 60 minutes in a concentrated or diluted solution of sulphuric acid removes seed coat impermeability. Cotton seeds, India teak wood seeds, and so on.

Stratification and scarification of breaking seed dormancy

The terms stratification and scarification are frequently used interchangeably, but they are all methods for breaking seed dormancy. They cover a wide range of techniques.

• Stratification is a broad term that refers to a variety of processes used to mimic natural conditions (typically temperature and moisture) that seeds require prior to germination.

• Scarification is a term used to describe a variety of techniques used to break physical dormancy. 

Many northern, native species respond well to cold-moist treatment. Simply mix seeds in moist media such as peat moss, vermiculite, perlite, or potting media to mimic the natural conditions they would encounter overwinter.

The mixture should then be stored in a container in the refrigerator for a period of time (typically around six weeks). For step-by-step stratification, see ‘Further reading’ below.

Reasons for seed dormancy

There are several major causes of seed dormancy. The following are a few of the causes of seed dormancy.

• Light

• Temperature

• Hard Seed Coating

• After-ripening period

• Inhibitors of germination

• The seed embryo’s immaturity

• Water permeability of the seed coat

• Oxygen permeability of the seed coat

• Seed coat that is mechanically resistant

• Solutes with high concentrations are present.

Types of seed dormancy

There are three types of seed dormancy

• Innate dormancy – is the condition of seeds that prevents them from germinating even when suitable conditions for seedling growth are provided. In some species, the inability to germinate due to the embryo being immature at the time of dispersal.

• Enforced dormancy – is the condition of seeds that are unable to germinate due to an environmental constraint such as a sufficient amount of moisture, oxygen, light, and a suitable temperature.

• Induced dormancy – This type of seed dormancy occurs when a seed has ingested water but is then placed in extremely unfavourable germination conditions. Finally, even under more favourable conditions, seed does not germinate.

Conclusion 

Dormancy occurs when there is a lack of germination in seeds or tubers despite the presence of the necessary conditions (temperature, humidity, oxygen, and light). Dormancy is caused by hard seed coat impermeability or a lack of supply and activity of enzymes required for germination. To overcome dormancy, the organic material is subjected to a number of physical and chemical pretreatments. Dormant seeds do not germinate within a specified time frame when a combination of environmental factors that are normally conducive to non-dormant seed germination is present. Delayed germination is an important function of seed dormancy because it allows dispersal and prevents all seeds from germinating at the same time.