Germplasm collection

Ramni Jamnadass

Ian Dawson

Tree Domestication Course

Nairobi

17 to 22 November 2003

Overview

• Reasons for collection?• Rangewide or local collection?• Collection approaches?• Practical issues?• Examples

Reasons for collection

• Immediate need expressed by farmersusers- national (farmers, extension workers, NGOs, researchers) or international (researchers) levels

• Conservation purposeswhere in collections, diversity represented is missing/ or insufficient ex situ storage, circa situ (on farms) and in situ

The natural resource base of many current or potentially useful species is being eroded

• Management researchDetermine seed physiology characteristics (increase longevity; decrease dormancy; increase germination rates, monitor germplasm health..)

Reasons for collection (2)

• Genetic improvement programmes

Collection to evaluate potential genetic improvement

Conventional breeding

Biotechnological enhancement of germplasm (pathogen resistant; drought resistant, enhanced product..)

The provision of superior tree germplasm can increase the uptake of, and return to farmers from, agroforestry systems

• First step in programs aimed at exploitation or conservation of plant genetic resources for future evaluation and utilization is the collection of those resources.

• A plant collector is a researcher consciously seeking to understand and record the bases of the adaptation of the plants to their general and specific environment and agricultural systems.

• He can do his job best against an in-depth background of knowledge of the ecological, human and agricultural characteristics of the area

Collection for domestication

• Diversity within ecological niches

• Diversity within and among species of important character traits (build up through evolutionary processes that keep provenances apart and impose adaptive pressures)

• Diversity of functionality (uses)

Rangewide or local collection?

Rangewide sampling (aims to capture genetic diversity built up through evolutionary processes that keep provenances apart across the ecogeographical range of a species)

Involves collecting numerous provenances across both geographical space and ecological clines (such as rainfall, soil and altitude gradients).

Rangewide or local collection? (2)

• Scale of collection (rangewide or local) depends on:

• Practical issues of germplasm exchange (e.g. recalcitrance)

• Legal issues of germplasm exchange• Relative focus on genetic improvement versus

physiological management• Importance of local genetic resource management• Trend toward community involvement

Collection approaches

• Strategies for sampling• Random systematic• Targeted• Seed• Vegetative

• Trend for community involvement• Advantages and disadvantages

bactris

Practical issues

• Rationale• Exploration• Logistics• Documentation• Biological standards• Flexibility• Processing and storage

prunus

Exploration

• Right time for seed collection • When the fruits/seeds are mature ?• How should tree seeds be collected ? • How do I know how much to collect? • Is it better to collect from the natural

forest or purchase seeds from a farmer?

• How do I handle fruits between collection and processing?

Basic Collection Strategy (Flexible)

When information on the population structure of the target species is lacking:

• Collect from 30-50(100) healthy mother trees• If insufficient material for procurement, sample more

sites• Sampling within a site should be random wrt phenotype,

but representative wrt to ecological variation• Sample as many sites as possible within the time

available• Ensure that sample sites represent as broad a range of

environments as possible• In natural forest, ensure regular distribution of seed

trees by keeping a distance of 50-100m

Examples

• Calycophyllum spruceanum• Prunus africana• Sclerocarya birrea• Warburgia ugandensis

calycophyllum

Examples (2)

• Dacroydes edulis

• Irvingia gabonensis and

I. wombolu• Case study Irvingia boy