Seed Technology - Lecture 3: Seed Collection

Seed Collection Planning

  • Species selection: Determining which species to collect.
  • Quantity: Determining how much seed to collect.
  • Seed sources/trees: Identifying where to collect.
  • Optimal harvest time: Determining when to collect.
  • Collection method: Determining how to collect.

Methods for Collecting Quality Tree Seed

Depending on:

  • Abundance of crop
  • Phenotypic characteristics of tree species
  • What is being collected (cones, fruits, seeds)
  • Terrain conditions

Methods Include:

  • Collecting from the ground
  • Collecting from treetops of felled trees
  • Collecting from standing trees – reaching from the ground
  • Collecting from standing trees – climbing trees
  • Collecting from bent trees

Seed Tree Selection

  • Seed trees should be selected in a homogeneous environment for easier identification of superior genetic characters.
  • In a heterogeneous environment, strong environmental effects make it difficult to select genetically superior trees.
  • A = strong winds
  • B = shading
  • C = flooding
  • Sites for seed tree selection (IFSP, 2000).
  • Selection of superior phenotypic seed tree (Illustrated by Wiyono, 2002).

Genetic Quality of Seeds

  • Seeds contain constitution/inheritance, which determines the potential performance of the progeny.
  • Poor genetic potential results in poor performance, regardless of treatment.
  • Genetic quality can only be proven by progeny test.
  • For unknown genetic quality (genotype) of seed trees, genetic inferiority is avoided by:
    • Avoiding inbreeding (proposed: at least 100 m apart)
    • Selecting phenotypically superior trees
      • Phenotype = the product of both genotype + environment; is the tree as we see it.

Genetic Viability

  • Factors influencing genetic viability:
    • Mating system
    • Reproductive success of trees
    • Successful regeneration of seedlings
    • Survival of saplings
  • Verifiers of genetic viability:
    • Tree density
    • Sapling growth
  • Examples of good superior trees marked for seed production.

Practical Measures to Avoid Detrimental Genetic Effects

  • Collect seeds from stands with heavily fruiting trees in close proximity.
  • Spread collection from a large number of widely dispersed trees (at least 15 trees with at least 100 m apart).
  • Collect from vigorous trees of good form.

Seed Maturity Indices

  • Collector's ability to judge via fruit appearances when a significant quantity of good seeds can be collected.
  • Samples from quick cutting test.
  • Observation of natural dispersal (indication of seed maturity).
  • Collect seeds just matured (not over matured).

Preparation Before Seed Collection

  • Calculation of seed quality and labor demand.
  • Analysis of potential seed markets and suppliers.
  • Identification of seed sources.
  • Maintenance of seed source.
  • Updating the seed source documentation.
  • Obtain permissions and agreements with seed‐source owners.
  • Preliminary assessment of flower and seed crop.
  • Training of staff (e.g., climbing, collection, processing).
  • Preparation of forms for seed documentation and instruction for collection, logistics, budgets, nursery‐man etc.
  • Maintenance of equipment (repair and replacement).
  • Purchase of new equipment and spare parts.
  • Preparation of seed‐processing and storage units.
  • A selection of Acacia seed collecting equipment used in Australia. From top left: Plant press with specimen and tags, small bag containing clean seed, large collection bag, 2×2 m collection sheet, flexible saw, leather gloves, bow saw, secateurs, fine sieve with bottom pan, large sieve, throwing rope with weight.

Seed Collection Techniques

  • Collection from the forest floor
    • Using nets to gather natural seed fall
    • Shaking of branches - accelerates seeds fall
  • Collection from crown of felled trees
  • Collection from standing trees
    • Climbing
    • Cutting off branches
    • Advance line techniques
  • Always maintain SAFETY during seed collection

Collection from the Forest Floor

  • Collecting seed from the forest floor is easy, inexpensive and the only practical method to collect seed of some species.
  • Seed collected from the forest floor has been exposed to soil moisture and soil microorganisms. It may have imbibed moisture and possibly lost viability.

Seed Collection Directly from Trees (Without Climbing)

  • Appropriate for small to medium sized trees.
  • Mature fruit is harvested by hand directly from the ground or with the aid of pole pruners or saws
  • Unreachable fruit bearing branches can be pulled towards the collector by using pole hooks or ropes.
  • Lower branches might also by reached by using a stool, chair or foot‐ladder.
  • Spreading mats or plastic sheets below the trees will facilitate the gathering of seed that drops to the ground.
  • Branch hook or pole with saw used in seed collection.

Other Collection Methods

  • For trees with fully matured pods or fruits that are near ready to fall (pods will be opening naturally) the branches can be beaten with a stick to shake down seeds or dislodge fruits.
  • Fruits or pods of small trees with branches drooping low can be easily reached and collected.
  • Hand collection of seed using racket and light-weight hopper.

Seed Harvest by Rope and Climbing

  • Seed harvest done by pulling the ends of weighted rope to break branches.
  • Seed collection by climbing trees
  • Seed collection by climbing is appropriate for medium to large trees where the mature fruit can not be reached from the ground.
  • Climbing trees by using ladders is a simple, safe, and quick seed collection method.
  • The disadvantage of using ladders is the necessity to transport them to the seed source and carry them between trees. This is particularly strenuous in steep areas.

Climbing Trees

  • Climbing trees without using equipment or tools is a common seed collection method throughout the world involving skilled climbers.
  • The collector collects mature seed from nearby branches and access additional branches by using pole hooks, tying the branches to a main stem or branch and then collecting seed.
  • Harvested seed is placed in a strong, but light and flexible bag carried by the collector that will be passed down using a rope or dropped directly to the ground.
  • Conversely, harvested seeds can be dropped directly to mats or plastic sheets spread below the tree.
  • The use of mats or plastic sheets keep the seed clean and facilitate gathering.

Tree Climbing Using Tools

  • Many government agencies, forestry industries and commercial seed dealers use special tree climbing equipment to collect seed.
  • Though expensive, this equipment greatly facilitates seed collection activities.
  • Tree bicycle in use, with safety harness, helmet and ropes.
  • Single‐strut sectional ladder.
  • Boom lift used in seed collection.

Advanced Line Technique

  • (A)‐(C) show stages from shooting the advanced line to drawing up the working rope,(D)‐(F) show possible uses of the working rope, (D) with block and tackle to pull man into crown, (E) for branch shaking and (F) to sever branches by means of flexible saw. (A.M.J. Robbins)

Other methods of seed collection

  • Schaumann Tree Shaker. This is one of a number of makes of tree shaker now on the market.

Use of Vacuum Seed Harvester in the Netherlands

  • (A) Collection from the ground and (B) Discharge of seeds into sack.

Seed Documentation

  • All tree seed should be documented to provide information regarding its origin, collection, handling and quality.
  • Undocumented seed is dubious. It may be of good to adequate quality, but it is more likely of low viability and inferior genetic quality.
  • Seed documents vary greatly depending on the needs of the collector/dealer, the requirements of user/consumer, and the purpose of documents.
  • A complete set of seed documents provides detailed information of the whole seed procurement process from seed source identification through seed sowing in the nursery.

Examples of Seed Documentation

1. Seed Source Document

  • Botanical and local name of the species
  • Location and site information of seed source (elevation, temperatures, rainfall, soil types, etc)
  • Type of seed source (seed trees, seed stand, seed production area, seed orchard, other)
  • Number of seed trees in the seed source
  • Age of seed source

2. Seed Collection and Handling Document

  • Botanical and local name of the species
  • Date of seed collection
  • Seed source from where the seed was collected
  • Number of seed trees from which the seed was collected
  • Average distance between seed trees
  • Weight of fruit/seed collected
  • Number of seed containers filled with the seed collected
  • Name of collectors
  • Seed lot number (a unique number to identify the seed collected on a specific date from a specific seed source)

3. Seed Quality Document

  • Botanical and local name of the species
  • Seed lot number
  • Date of seed testing
  • Seed purity
  • 1000 seed weight test
  • Moisture content
  • Percentage of germination or viable seed

Seed collection methods and post-harvest handling

  • https://vimeo.com/277477263