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 farmers users- national (farmers, extension workers, NGOs, researchers) or international (researchers) levels Conservation purposes where 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 research Determine 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 m

Examples Calycophyllum spruceanum Prunus africana Sclerocarya birrea Warburgia ugandensis calycophyllum

Examples (2) Dacroydes edulis Irvingia gabonensis and I. wombolu Case study Irvingia boy