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Seed Germination

Seed Germination. Processes and Requirements. Germination. What is germination? I have used this word before in class It is when the first embryonic root emerges from the seed coat Germination is a process that begins only when certain conditions are met. Germination.

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Seed Germination

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  1. Seed Germination Processes and Requirements

  2. Germination • What is germination? • I have used this word before in class • It is when the first embryonic root emerges from the seed coat • Germination is a process that begins only when certain conditions are met

  3. Germination • Seeds from some plants will germinate as soon as they are released • Others go dormant (a type of hibernation) • They remain dormant until proper conditions are met • What do you think some of those conditions are?

  4. Types of Dormancy • Stratification • Triggered by temperature • Must go through a period of cold • And then warm up • Scarification • Triggered by break-down of the seed coat • What are some ways that a hard seed coat could be broken down?

  5. Stages of Germination • # 1 – Imbibition • Absorption of water • Usually dormant seeds have 5-10% moisture content • At proper conditions water is imbibed very quickly • What does this do to the seed? • It swells • Becomes turgid

  6. Stages of Germination • # 2 – metabolic activity surges • Proteins are made • Enzymes are produced • Amylase – converts starch to sugar • Protease – breaks down stored proteins into amino acids • Sugars and amino acids are sent to meristems • That is where growth takes place • Tips of the root and shoot

  7. Stages of Germination • #3 – metabolic processes increase • Swelling cells break seed coat • Root tip emerges downward • Stem shoot grows upward • Shoot begins photosynthesis • Root begins absorbing water and nutrients

  8. Conditions for Germination • Conditions have to be right for the new plant to survive • They include: • Water • Air • Temperatures • Light/Darkness

  9. Conditions for Germination • Water triggers the process • How much moisture is usually in the seed? • Oxygen must be present for the seed to germinate • It is needed for cellular respiration • Converts stored food into energy

  10. Conditions for Germination • Temperature • Some seeds can begin germinating at as low as 32°F or as high as 105°F • Optimum Temperature is usually between 65°F and 80°F • Temperature influences metabolic activity • Usually faster at higher temps and slower at lower temps

  11. Conditions for Germination • To begin germination: • Some seeds actually need light • Others need darkness • Light sensitive seeds have a photoreceptor pigment in their seed coat • Called Phytochrome • It sends a message to the seed to begin or stop germination

  12. Seed Quality • Is seed quality important? • Why • If you buy a bag of seeds to plant, how many do you want to grow? • Good seeds make good plants

  13. Seed Quality • Defined by two things: • Viability • Ability of seeds to germinate under optimal conditions • Vigor • Ability of seeds to germinate under different conditions and still produce healthy plants

  14. Seed Quality • Seed producers test seeds for germination rates • These rates are printed on the label of the seeds you buy • How do they perform the test?

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