UNDERTAKE PROPAGATION ACTIVITIES - AHCNSY203A

Question 10

Describe 3 methods of overcoming dormancy of seeds?

Softening Seed Coats and Other Coverings---
Scarification is any process of breaking, scratching, mechanically altering, or softening the seed coverings to make them permeable to water and gases.

Mechanical Scarification
Mechanical scarification is simple and effective with seeds of many species if suitable equipment is available. These seeds are dry after such treatment and may be stored or planted immediately by mechanical seeders.
Chipping hard seed coats by rubbing with sandpaper, cutting with a file, or cracking with a hammer or a vice are simple methods useful for small amounts of relatively large seed. For large scale mechanical operations, special scarifiers are used.
Scarification should not proceed to the point at which the seeds are injured.

Hot Water Scarification

Drop the seeds into four to five times their volume of hot water 77-100
removed, and the seed soaked in the gradually cooling water for 12-24 hours. The seeds should usually be planted immediately after the hot water treatment.

Acid Scarification
Dry seeds are placed in containers and covered with concentrated sulphuric acid in a ratio of about one part seed to two parts acid. Containers should be glass. The mixture should be stirred cautiously at intervals during the treatment to produce uniform results and to prevent accumulation of the dark, resinous material from the seed coats.
At the end of the treatment period the acid is poured off, and the seeds are washed to remove the acid. The seeds can be washed for 10 minutes in running water. The acid treated seeds can either be planted immediately when wet, or dried and stored for later planting.

Warm Moist Scarification
Keeping seeds in a non sterile, moist, warm medium for several months can soften seed coasts through microorganism activity. 

High Temperature Scarification

Seeds of certain species of native plants with hard seed coats germinate extensively after a forest or range fire. Seed coats are modified by the high temperatures. This action allows release of the seeds which are then able to germinate. 

Seed dormancy
https://en.wikipedia.org/wiki/Seed_dormancy


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Question 18

What is pasteurisation and how is it used in propagation environments?

Good hygiene is imperative to healthy plant growth.
Pasteurisation is a heat treatment process that destroys pathogenic micro organisms.

The commercial grow may consider this technique:

Soil steam sterilization (soil steaming) is a farming technique that sterilizes soil with steam in open fields or greenhouses. Pests of plant cultures such as weeds, bacteria, fungi and viruses are killed through induced hot steam which causes their cell structure to physically degenerate. Biologically, the method is considered a partial disinfection. Important heat-resistant, spore-forming bacteria survive and revitalize the soil after cooling down. Soil fatigue can be cured through the release of nutritive substances blocked within the soil. Steaming leads to a better starting position, quicker growth and strengthened resistance against plant disease and pests. Today, the application of hot steam is considered the best and most effective way to disinfect sick soil, potting soil and compost. It is being used as an alternative to bromomethane, whose production and use was curtailed by the Montreal Protocol. "Steam effectively kills pathogens by heating the soil to levels that cause protein coagulation or enzyme inactivation."^[1]

Wiki

or

The home gardener is able to pasteurise seed raising or potting mix in their domestic oven. 

Pasteurizing Medium

Potting media mixed by home gardeners should be pasteurized to kill weed seeds, soil-borne insects, and pathogens. Pasteurization destroys most organisms and is done by applying heat until the soil reaches 180oF (82oC) for 30 minutes. When temperatures are raised above 212oF (100oC), most of the soil borne organisms are killed and the soil is considered sterile. Gardeners can pasteurize homemade potting soils using a kitchen oven; however, a long-lasting earthy odor can develop in the oven. To pasteurize soil, preheat the oven to 180oF. Then fill a pan with about 4 inches of moist soil and cover it with aluminum foil. Insert a candy or meat thermometer to monitor temperature and place the pan in the oven. When the thermometer reads 180oF, leave the pan in the oven for 30 minutes longer, then remove it and allow the soil to cool. Seeds can then be sown in the soil, or it can be used as a transplant medium for seedlings.

and

Remember to Sterilize Containers and Tools!!!

Efforts to pasteurize soil are in vain if contaminated tools, seed flats, or pots are used. Each should be disinfected by soaking it for 30 minutes in a 10% solution of chlorine bleach (one part bleach and nine parts water). Tools and containers should then be rinsed and allowed to dry before using them again.

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Question 21

Describe the differences between the following cutting types and describe the best time of the year to undertake these techniques.
a) Softwood cutting
b) Semi hardwood cutting
c) Hardwood cutting


a) Softwood
Softwood cuttings are prepared from soft, succulent new growth of woody plants just as it begins to harden . Shoots at the softwood stage will snap easily when bent. The youngest leaves have not yet reached their mature size.  Spring - Summer.

b)Semi-hardwood
Semi-hardwood cuttings are taken from the current season's growth after the wood has matured. The wood is firm and all leaves are full size. This occurs in Summer to early Autumn in most plants. Many broadleaf evergreens (e.g., boxwood, holly, rhododendron) can be propagated by semi-hardwood cuttings.

c) Hardwood

Hardwood cuttings are prepared from shoots that grew the previous summer. They are cut in winter or early spring while the plant is still dormant. The wood is firm and does not bend easily. Some deciduous shrubs and needled evergreens will root from hardwood cuttings.

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Pertaining to Question 29.  (for my personal info)

Describe 3 hygiene practices that are effective to use within a propagation work area.


Hygiene in Plant Propagation:

https://www.ngia.com.au/Attachment?Action=Download&Attachment_id=1593

by Nursery & Garden Industry Australia

Nursery & Plant Hygiene:

http://www.worldagroforestry.org/NurseryManuals/Research/Hygiene.pdf

How to Sprout seedlings indoors:

http://extension.oregonstate.edu/gardening/how-sprout-seedlings-life-indoors --------------------------------------------------------------------------------------------------------------------------