SEED GERMINATION hypocotyl epicotyl germination and it's importance

Seed germination
Hypocotyl germination
Epicotyl germination
Seed coat
Important of seed germination

1. Seed Germination

2. Seed Seed is a material which is used for planting or regeneration purpose. Scientifically, seed is a fertilized matured ovule together covered with seed coat is called seed or it is propagating material. Technology point of view; Seed is a fertilized ripened ovule consisting of three main parts namely seed coat, endosperm and embryo, which is due course give rise to a new plant.

3. Seed Germination “The process that begins with the water uptakes by the dry seed and ends with the emergence of the embryonic axis, usually the radicle, from its surrounding tissue.”

4. Parts of a seed Plumule: Tissues developed as a part with leaves of a plant in germination is called plumule. It is name as epicotyl also. Radical: Tissues developed as root system of a plant in the germination is identified as radical.

5. Hypocotyl Bunch of tissues in between radical and plumule is named hypocotyl. It grow as basal part of plant in germination. Cotyledons: It is difficult to identify because of seed leaf in monocotyledonous seeds is being under worn condition. But in dicotyledonous seeds, both of seed leaves have accumulated foods.

6. Micropyle Very small pore is positioned in seed coat. Water absorption germination is progressed through this.

7. Basic parts of a seed Embryo Endosperm Seed coat Embryo: The embryo is a baby plat. It consists of a plumule, radical and cotyledon. The embryo is the young multicellular organisms before it emerges from the seed.

8. Endosperm The endosperm is a source of stored food, consisting primarily of starches. It is the structure that has been formed to provide nutrition for embryo in germination. Seed coat: The seed coat consists of one or more protective layers that encase the seed. The seed coat is tough and waterproof. It covers and protects the embryo and the food supply.

9. Germination The emergency and development from the seed embryo of those structures which seed indicate the ability to produce a normal plant. Condition necessary for germination: Water Gases Temperature Light

10. Gases Air is composed of about 20% oxygen, 0.03% carbon dioxide, and About 80% nitrogen gas oxygen is required for germination of most species. Carbon dioxide concentrations higher than 0.03% retard germination. While nitrogen gas has no influence.

11. Temperature Seed germination is a complex process involving many individual reactions and phases, each of which is affected by temperature. The optimum temperature for most seeds is between 15 and 30° C. The maximum temperature for most species is between 30 and 40°C. The response to temperature depends on a number of factors, including the species, variety, growing region, quality of the seed, and duration of time from harvest.

12. Water Water is the most essential factor. The water content of mature, air-dried seeds is in the range of 5 to 15%, Well below the threshold required for fully active metabolism. In addition, water uptake is needed to generate the turgor pressure that powers cell expansion, the basis of vegetative growth and development.

13. Mode of Germination Seed present two mode of germination based on the behavior of the cotyledons or storage organs. Epigeal Germination Hypogeal Germination

14. Hypogeal Germination The cotyledons do not come above the soil surface. This type of germination is found in wheat, barley, maize and pea.

15. Epigeal Germination The cotyledons come out above the soil surface and generally turn green and act as first foliage leaves. This type of germination present in groundnut, bean, cotton, and sunflower.

16.   Pattern of seed Germination Most seeds undergo a specific sequence of events during germination. Prior to germination, seeds are in a “maintenance” phase. It is often characterized as dormancy being imposed by ABA, metabolic blocks or some other agent hindering the transition to germination.

17. Seed dormancy is a mechanism by which seeds can inhibit their germination in order to wait for more favorable conditions (secondary dormancy). However, primary dormancy is caused by the effects of abscisic acid during seed development.  Germination can be divided into three phases corresponding to the phases of water uptake. Phase I Phase II Phase III

18. Phase I: Imbibation The dry seed takes up water rapidly by the process of imbibation. It is the first key event that moves the seed from a dry, dormant organism to the resumption of embryo growth. The extent to which water imbibation occurs is dependent on three factors: (1) Composition of the seed (2) Seed coat permeability (3) Water availability

19. Phase II: Lag phase Water uptake by imbibation declines and metabolic processes, including transcription and translation, are reinitiated. The embryo expands, and the radicle emerges from the seed coat. Phase III: Mobilization of reserve food Water uptake resumes as the seedling grows, and the stored food reserves of the seed are fully mobilized.

20. Importance of seed germination Seed germination determines continuous plant production necessary for human survival with regards to the supply of medicinal plants, feed for animal grazing, and food security. The propagation of some plants is only possible by seed, and if they are difficult to germinate, this threatens their continuous existence.

21. . How long does it take for the first seed to germinate? Usually, it takes around 1 to 2 weeks to germinate. Some plants (for instance mini tomato, chilli pepper and rosemary) may take up to 3 weeks. All lettuce and kale plants are very sensitive to high temperatures (above 24 °C / 75 °F). So their germination might be inhibited by that.

22. Could a 2000 years old seed still grow? Researchers have successfully grown dates from 2000-year-old seeds recovered from an ancient fortress and caves in the Middle East. The find reveals how ancient farmers were selectively breeding dates from around the region, and it could give clues to how dates can survive for millennia.

23. Conclusion of seed germination Seeds have the ability to germinate in the presence of moisture, air, and light under the right temperature, even in the absence of soil. If you are interested in knowing more about seed germination, you can repeat the same experiment but keep the bag in a dark place instead of placing it in light.