Treatments to Overcome Seed Dormancy

Softening seed coats and other coverings (Scarification)

Mechanical Scarification

Sandpaper, hammer, knife, tumbler.

Hot Water Scarification

Drop into hot water (77 to 100^oC), remove from heat, allow to cool and soak for 24 hours.

Acid Scarification

Seeds, in small batches, are brought into contact with 93% Technical Grade sulphuric acid. At the end of a set period of time (from as little as a minute to as much as an hour and a half), seeds are rinsed and acid is neutralized with baking soda. Initially shiny seed coats would appear dull after this treatment.

Warm Moist Scarification

Keep plants in warm moist soil or unsterilized sand for several months to soften seed coats through microbial activity. Seeds may also be planted directly in the summer or fall while soil temperatures are warm.

Stratification

Refrigerated Stratification

Stratification is accomplished by placing seeds in moist planting medium in a cold environment for a period of time (two weeks to three months). Seeds require moisture, cold and oxygen. In general, this period of time allows an undeveloped embryo to mature.

Outdoor Stratification

Seeds may be kept outdoors through the winter in lined pits or raised beds. They must be protected from freezing, drying and rodent predation (use wire netting in the soil). Pits or beds are layered with clean sand, medium with seeds, more clean sand, etc.

Outdoor Planting

Some categories of seeds may simply be planted outdoors in the fall and natural stratification is allowed to happen.

Leaching

Inhibitors in seed coat

Leaching simply requires washing seeds with fresh water. It may be accomplished by running water over seeds in a container (mason jar) for 12 to 48 hours. For longer washing, and for seeds that produce a large amount of soluble substances, water should be changed every 12 hours, or seeds should be washed in running water. If you use running water or a bubbler, foam may be produced; either use cheesecloth to prevent seeds from being carried out of the jar, or sit the jar in a pan.

Inhibitors in pulp

Some chemical inhibitors are found in the pulp of fleshy fruit. Pulp should be removed by soaking or maceration; seeds should then be washed.

Laboratory Treatments

Prechilling

Store imbibed seeds at 5 to 10^oC for five to seven days before attempting germination.

Predrying

Subject dried seeds to 37 to 40^oC for five to seven days prior to germination.

Alternating Temperatures

Use daily alternation of temperatures , going from 15-20^oC to 30^oC, with seeds held out the lower temperature for 16 hours and the higher temperature for 8 hours.

Light Exposure

Light should be provided by cool-white fluorescent lamps, at high intensity, for at least eight hours daily. Seeds should be imbibed and placed on tip of the medium.

Potassium Nitrate

Moisten substratum with 0.1 to 0.2 percent potassium nitrate solution.

Hormones

Soak in gibberellic acid or cytokinin (kinetin) solution. Twelve to 24 hour soak is recommended. Concentrations vary.