Selfing in Clonal Seed Orchards of Slash Pine

Using 12 gene-marker clones occurring in eight clonal seed orchards, we estimated the frequencies of viable self-fertilized seed resulting from wind pollination over a period of 5 years. Frequencies averaged 2.5 percent but varied greatly among orchards and years. Using data from controlled self and cross-pollinations, we further estimated that frequency of total self-fertilized seed (viable + nonviable) averaged 9.5 percent. More selfing occurred in lower crowns than in upper crowns. Emasculation of a portion of the ramets suggested that selfing within ramets was greater than between ramets of the same clone. Implications for orchard management are discussed. Forest Sci. 28:71-78.