Pollen migration in predominantly self-fertilizing plants: barley.

In barley, a heavily self-fertilizing species (approximately 99%), most outcrosses occur between plants that grow closely adjacent to each other. Outcrosses have been detected only rarely between plants that are separated by a meter or more. In this article we present evidence that outcrosses can occur at distances up to 60 m and we discuss the implications of this longer-distance pollen migration on the maintenance of the genetic integrity of pedigreed stocks and experimental populations.