What is Seed Germination?
Seed Germination is defined as one of the vital process by which all the species of plants got generated from a single seed and how it gets adapted to a particular environment and grow itself as a crop or as an herb or as shrub or a tree.
The best example that we come across our day-to-day life is sprouting of pulses in our kitchen or young plants developing in our kitchen garden.
Process of Seed Germination
When we sow a seed in a mud, first the seed starts absorbing water from its outer environment or directly from the soil, which results in bulging of seed and its seed coat gets moisture and becomes very vulnerable at a particular temperature.
This stage of the seed which can be seen from one to two days of sowing is commonly referred to as imbibition.
It further resumes its growth process by activating several enzymes and starts its respiration and initiates the production of proteins and stores nutrients in it by metabolising those necessary proteins.
Hence, it is said that sprouts are rich in proteins.
This stage of the plant is generally referred to as lag phase. Then the seed coat starts rupturing and gives rise to a small radicle, which later forms the primary root of a plant.
This helps the plant to absorb the underground water along with other nutrients present in the soil and helps in further growth of the plant.
The slowly starts growing the plumule of the plant which later develops into the stem portion of the plant.
As days move on seeds modify itself as seedling, then plumule starts growing upwards giving rise to leaves and other floral parts of the plant.
Optimum Condition for Seed Germination
Not all the seeds have the capability to grow at any conditions we sow, certain seeds grow only at certain conditions and certain soil and climatic conditions.
The things that are necessary for a plant to grow in a good condition are listed below.
As every living organisms’ water is the most vital component for a seed to germinate.
Though some seeds do not require much water for their growth they need at least a minimal quality of water at certain intervals.
It depends on the dry weight of the seed. As discussed above the seed starts its germination process by absorbing water which is necessary for the nourishment of the embryo by providing dissolved oxygen and soluble supplements for their growth.
The dissolved oxygen helps the seed coat to become softened and converts the seed into a sapling by rupturing the seed coat.
As water oxygen is also very much important for the seed growth, which is obtained through the water in a dissolved form or through the porous soil.
But the deep buried seeds are not capable to use the oxygen from the soil pores.
Oxygen is vital for the metabolic process of the seed in terms of aerobic condition.
If the seed wants to grow in a proper manner without any deficient conditions then the temperature should be maintained at an average of 25 to 30ºC. But in some cases, the seeds need a temperature of 5 to 40ºC.
Hence the temperature varies according the particular regions where they are native to and other environmental factors.
D. Light and Dark Cycle
This depends on the nature of certain seeds, some seeds do not germinate if sunlight falls on them, such kind of seeds are grown in a dark condition and after germination they are brought to the field.
Whereas most of the plant needs sunlight for the germination and throughout their lifetime.
Thus, the seed germination needs all these vital factors and generation of plumule and radicle is said to be completion of seed germination.
Factors Affecting Seed Germination
Factors affecting seed growth or germination may be both internal and external and they are listed below as follows.
Seed dormancy is considered as one of the important factors in germination process which means that seeds do not germinate if they met any unfavorable conditions during their process of undergoing their growth.
During this period the seed coat which allows the passage of water restricts the water to absorb so that the oxygen and nutrients necessary for their growth is limited.
So that the seeds remain as such without any development. But in some cases, the plant growth regulators help in the growth of the plant.
However, some seeds germinate within a week where as others take their own time to germinate.
As mentioned above water, oxygen and temperature are considered as important factors for the germination of a plant.
Seed growth gets affected when the water is supplied at higher amount than the needed quantity and also when it is supplied in very low quantity or there is no supply of water.
So, it is important to know the nature of seeds and their adequate flow of water.
While the seeds start its germination process it intakes large amount of water than other intervals, so it is checking the availability of oxygen for the growth of the plant.
Seeds require only the appropriate temperature necessary for their growth if the temperature is more vigorous than needed then seeds starts shrinking and it will die or degenerate.
So, the seed must be sown in optimum environmental conditions by considering the environmental factors.
Seed Germination Citations
- Seed dormancy and germination. Curr Biol . 2017 Sep 11;27(17):R874-R878.
- Seed germination traits shape community assembly along a hydroperiod gradient. Ann Bot . 2020 Jan 8;125(1):67-78.
- Phytochrome Regulation of Seed Germination. Methods Mol Biol . 2019;2026:149-156.
- Seed germination and dormancy: The classic story, new puzzles, and evolution. J Integr Plant Biol . 2019 May;61(5):541-563.
- The biomechanics of seed germination. J Exp Bot . 2017 Feb 1;68(4):765-783.
- Studies on the molecular mechanisms of seed germination. Proteomics . 2015 May;15(10):1671-9.