Germination &Seed DepthGreenhouse

ObjectiveAnalyze the effects of planting

depth in relation to seed germination.

Quick ReviewPropagation - Also defined as the

reproduction of plantsThe most common methods is

through seedsGermination- The beginning of

growth from a seedGermination Rate- The percentage

of seeds capable of germinating

Indirect SeedingA process in which the seed is

sown in a place separate from where the plants will eventually grow to maturity.

The seedlings are transplanted one or more times before reaching the permanent growing area.

Sowing SeedsTomato:

Time to Seed – 4 to 6 weeks before transplant date

Germination time in days – 7 to 14 days

Planting requirements – cover seed ¼ inch

Germination Temp. – 70 to 80 degrees F

Planting Seeds planting depth is a key factor in successful

germination. Seeds planted too deeply will likely rot

before they germinate seeds planted too close to the surface will

dry out, and produce spindly growth.

Some seeds need to be sown at or near the surface to allow exposure to sunlight, or they will refuse to germinate.

Depth of Planting The most common cause of poor

germination is the depth at which the seeds are sown.

Small seeds should be planted on the soil surface and pressed or rolled in for best results They contain only enough stored food

for a limited period of growth. If the seedling is to survive it must

emerge from the soil and quickly begin to produce its own food.

Depth of Planting If seeds are too deeply buried beneath

the soil surface, the seedling will either… exhaust its food reserve prior to reaching

the soil surface causing its deathOR

lack of sufficient oxygen will prohibit germination altogether.

Conditions for Germination 1) Water is needed to:

Activate hormones and enzymes Swelling of the seeds = bursting of seed

coat. Transport of simple materials to the

embryo – to be used for respiration and growth.

Metabolic and enzyme actions – occur in solution, therefore need water.

Conversion of storage compounds into simple components (i.e. starch to glucose)

Conditions for Germination 2) Oxygen is needed for aerobic

respiration. Without a supply of oxygen, seeds fail to

germinate because of the lack of energy – in the form of ATP.

Conditions for Germination 3) Suitable temperature

All reactions (in germination) are controlled by enzymes.

Optimal temperature for enzyme activity leads to faster rate of germination.

Freezing = inactivates enzymes Very high temperatures = denatures

enzymes

Seed Size and Planting Depth Food for the seedling is stored within the

seed; this is the edible part of plants we eat such as rice, wheat and corn.

The smaller the seed, the smaller the reserves of food and the less energy the growing plant has to push up to the surface. So smaller seeds need to be planted at shallower depths.

For instance, carrot seeds are less than one-eighth of an inch long and should be planted about one-quarter inch deep.

Corn seeds, thick, packed with food and over one-quarter inch long, can be planted as deep as 4 inches, though 2 inches or less is better

Sunlight The more soil that covers a seed, the less light it

receives. Now, for some seeds, this is a good thing. They won't germinate in the light, requiring total darkness to begin the process. Others need light and won't germinate if they are buried by even a quarter inch of soil. Luckily, most seeds are less picky about light. Always follow the directions on your seed packet, especially if the instructions include details such as "press into the soil lightly and do not cover," indicating that the seeds need light to germinate.

Let’s Germinate! Plant tomato seeds at various soil

depths Surface Normal Deep

Hypothesize the results of the plantings.