Introduction

In the past, collecting activities have concentrated on particular species or on certain genetic characters which plant breeders were seeking. At present, because of the rapid rate of genetic erosion of crops in most parts of the world, exploration trips are now becoming ‘rescue operations’ in which as much diversity as possible is being collected. The concept of ‘now or never’ is in the forefront of the collectors’ minds.

The methodology of collecting and the scientific basis of sampling have also received considerable attention. Whereas some 30 years ago it was thought sufficient to collect a few seeds from a single plant, write one or two words on a label and put them all into a bag, this method is now thought to be most unsatisfactory.

The genetic resources collector is looking for diversity. Whereas the botanical or horticultural collector was content to collect a few herbarium specimens and a small packet of seeds, to serve as a representative for a species in a particular area, the genetic resources collector needs not uniformity, but diversity. How is this to be accomplished?

Studies of the population genetics of wild species by Allard (1970) and his colleagues showed that more sophisticated methods were needed if a reasonable amount of the genetic diversity of a species was to be captured.