The after-effects of reproductive environment in shortleaf pine

Abstract

Thirteen identical controlled crosses were made among 22 shortleaf pine ( Pinus echinata Mill.) clones growing in two contrasting reproductive environments: a seed orchard in central Arkansas, USA (34.6°N) and a clone bank in south Mississippi (30.5°N). The resulting seedlings from both reproductive environments were planted at both locations where the seed was produced. After 4 years in the field (5 years from seed), trees from seed produced in the two environments differed significantly in height. The reproductive environment × family interaction was also significant, however, indicating that the effect depended upon the genetic background of the parent trees. By age 9 years, differences were no longer statistically significant. Allozymes were assayed in seed produced in the two reproductive environments. Chi-squared tests of heterogeneity of segregation ratios for polymorphic loci showed significant differences between the two environments for many cross/loci combinations. Although the pattern of differences was not obviously linked to differences in growth, gametophytic selection is suggested as a possible explanation for the after-effects.