Germplasm collection Ramni Jamnadass Ian Dawson Tree Domestication

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 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 -100 m

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

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