Seed Storage and Transportation Guidelines

Course Information

• Course Title/Code: Forest Seeds and Nursery Technology (For3091)
• Course Credit: 3 Credit Hours and 5 ECTS
• Instructor: Yadesa A.
• Year: 2024 AY

Handling of Fruit and Seed between Collection and Processing

• Seed handling encompasses collecting, sorting, cleaning, storing, and preparing seeds for planting or processing, ensuring viability and quality
• Effective seed handling boosts crop yield by promoting planting of high-quality seeds, crucial for agricultural productivity
• Proper seed handling supports ecosystem restoration by encouraging the growth of native plant species, vital for habitat and biodiversity recovery

Reduction of Bulk and Maintaining Viability

• Fruit, not seeds, are typically collected from trees
• Sun drying of fruits and seed extraction in the field is suitable in specific climates
• In other cases, quick transport of fruits to processing depots permits controlled extraction
• Careful handling is needed when seeds are not extracted in the field to prevent deterioration due to temperature, humidity, moulds, and overheating

Maintaining Identity

• Each fruit container should be correctly labeled
• Identical labels inside and outside containers prevent loss of information when dispatched
• Weatherproof labels should include species, seed lot number, geographic location/source, weight of seed, date of collection, and collector's name
• A copy of the seed collection data sheet or certificate of origin with seed lot number reference should accompany or be mailed with the seed

Hygiene and Contamination

• Special measures may be required to prevent damage from pests and diseases
• Insecticidal or fungicidal dusts are sometimes advisable but require extreme care to avoid chemical damage to the seed
• Maintaining fruit hygiene, particularly through good ventilation, is preferred to chemical reliance
• Storing sacks off the ground protects against rodents
• Prompt collection of fallen fruits helps minimize future losses

Temporary Storage at Seed Processing Depot

• If fruits cannot be transported immediately, temporary field storage in sheds or shelters is needed
• Shelters should have proper ventilation, and sacks should be spaced on racks or hung from hooks
• Open-sided or well-ventilated sheds are preferred, and canvas tarpaulins or polyethylene sheets can give overhead protection in open storage
• Sacks should not be piled too high.

Condition during transport

• Minimize time between dispatch from collection site (farm, depot) and the central processing depot
• Part of planning must include adequate transport to avoid delays and breakdowns
• Even short stops increase heat build-up in fruit and cone sacks
• Drivers should be briefed on load details and proper handling, aiming for prompt delivery
• Open trucks and trailers are preferred to close vans for improved air circulation

Seed Processing

• Fruit, not seeds, are usually harvested
• Some species are referred to as seeds but are technically fruits used for planting
• Seeds must be extracted from their coverings

Forest Seed Sorting

• Seed sorting aims for purity and quality in the final product.
• Prediction and control of this are generally difficult

Pre-Cleaning

• Cones and fruits should be cleaned of impurities for subsequent extraction, cleaning, storage, or sowing
• Cleaning is often done in large operations via oscillating screens or vibrators. Also, pre-cleaning via flotation is used.
• Hand cleaning may be used in small-scale operations to remove major debris

Pre-Curing

• Deliberate storage and slow air-drying of fruits/contained seeds to prepare them for operations of kiln drying, extraction, and long-term storage
• Seeds do not ripen uniformly, ideally, there is proper timing

Seed Extraction

• Extraction involves removal of seeds from fruits
• Methods for extraction vary by fruit type/species, e.g., drying, rubbing, crushing, scraping, etc

Operations between Extraction and Storage

• Seed lots contain debris that must be removed after extraction
• Sound seeds must be separated from empty or nonviable seeds and any inert fruit fragments
• Seeds must be properly graded for uniformity

Seed Storage

• Seeds should be stored after processing until dispatching
• Factors to consider for seed storage include temperature, humidity, moisture content, light, and protection from diseases and pests
• A cool, dry, dark, well-ventilated location that is protected from pests and diseases is essential

Trade and Distribution of Seed

• Seed transfer happens when the seed producer and user are geographically apart.
• Market pricing reflects procurement costs and seed quality
• Documentation like seed test records and origin/source documents are crucial
• Distance between producers and consumers can impact distribution

Seed Testing

• Seed testing measures the quality of seeds, determining the number of healthy plants expected to grow from a given amount of seed
• Tests include purity, authenticity, seed weight, germination, viability, moisture content, and seed health.
• The International Seed Testing Association (ISTA) sets standards for testing seed quality.

Seed Quality and Sampling

• Seed quality refers to purity, viability, vigor, and health
• Seed quality is assessed via seed testing, preferably shortly after collection/purchase
• Storage can negatively impact seed quality; testing should thus be repeated after long-term storage to estimate the seed amount needed to produce the required number of seedlings for planting

Seed Sampling

• Seed testing should only be conducted on representative samples due to their destructiveness.
• Samples are drawn prior to testing, and they should be representative of the entire seed lot
• Sub-samples are drawn from containers or parts of containers (for large seed lots)
• Combining a few small seed lots to test as a single lot may be useful in some circumstances

Genuineness (True-to-type) Test

• True-to-type seeds will reliably produce offspring reflecting the parent tree's characteristics.
• This is critical for reforestation, genetic diversity maintenance, and optimizing timber/fruit quality.
• True-to-type seeds are paramount in forestry; using seeds inconsistent with that can be risky

Purity Test

• Seed lots contain seeds from other species, fruits, twigs, leaves, and dirt, alongside the target species
• Pure seed refers exclusively to the seeds of the target species, both viable and non-viable
• Purity percentage is calculated by separating pure seed from other elements

Seed Moisture Content Test

• The test involves measuring moisture content, primarily to ensure proper condition for storage
• Oven-drying the seed sample is required.

Seed Weight Determination

• This test calculates the weight of 1000 seeds to determine weight per unit
• The quantity of seed in short supply can be reduced to 100 or 500 seeds

Germination/Viability Tests

• These tests determine a seed lot's capacity to produce healthy seedlings, crucially for estimating the amount of seed needed for a desired number of seedlings
• Direct tests for germination are suitable for easily germinable seeds
• Indirect tests for viability are more suitable for difficult-to-germinate seeds

Seed Pre-Sowing Treatments

• These methods help overcome seed dormancy, accelerating germination and seedling production.
• Method variations range in time commitment, from few minutes to a few days to complete

Soaking in Cool Water

• This method helps break physical, mechanical, and chemical dormancy in seed, often done over a single day.

Soaking in Hot Water

• This method is effective for breaking dormancy in seeds with hard, thick, and waxy seed coats

Mechanical (Scarification) Methods

• Seed coat or fruit shells are mechanically scarified (holes cut or scraped for water uptake)
• Post-treating soaking in cool water is usually done

Fire or Heating Methods

• This involves spreading and burning dry grass to stimulate germination
• Used for cracking seeds with thick shells

Trade and Distribution of Seeds

• Seed transfer occurs between geographically separated seed producers and seed users
• Price reflects procurement and seed quality, with quality tests recorded
• New species and small-scale producer needs may create unique issues to be addressed by the distribution system

During Tree Seed Dispatching

• Seed needs to reach end-users with minimum loss of viability, using optimized transport methods

End-users

• End-users may include plant owners, small-scale farmers, and others
• Their needs and capacities for seed usage can vary

Quiz Questions

• Describe seed extraction and its uses
• List tree seed pre-cleaning methods
• Describe key factors to consider when storing tree seeds