DEVELOPMENT OF METHODS FOR AND EVALUATION OF JUVENILE CHARACTERISTICS IN JUNIPERUS NURSERY STOCK SEED SOURCES.

摘要

A study of 106 Great Plains Juniperus half-sib families (78 J. virginiana and 28 J. scopulorum) was made over a two-year period beginning after seed germination in 1978. The study was conducted in a "common garden" environment of a nursery unit at the USDA Forest Service Bessey Nursery in Halsey, Nebraska.; Chemical constituents, foliage color changes, height growth, cessation of growth and winter injury were measured and evaluated.; Statistical analyses of chemical constituents were made using two multivariate techniques--canonical variate analysis and principal coordinates analysis. Thirty chemical characteristics were analyzed in each of the methods for determination of the relationships among 17 geographical populations composed from 95 samples. A graphical hybrid method was used to plot distance diagrams to test for intermediacy of the 17 Great Plains populations. These analyses supported the presence of two species, J. virginiana and J. scopulorum, and the possible hybridization between the two species.; A technique for rating foliage color change for evaluation was developed. Foliage color change was closely associated with and possibly initiated by temperature. A north-south trend of foliage color in J. virginiana supported genetic control over foliage color in both actively growing and dormant seedlings.; Height growth was variable among families (seed sources), but more uniform within a family.; Growth cessation of all 106 families occurred during a three-week period from October 5 to October 26, 1979. Photoperiod appeared to have close association with growth cessation in these two Juniperus species. It was observed that families of southern origin continued growth the latest of all families measured. The start of growth cessation was closely associated with the beginning of foliage color change in early October.; Seedlings of J. virginiana families which had extensive late season, late August through mid-October, foliage growth suffered more winter injury than those which had lesser amounts of late season growth. All families originating from sources south of 37(DEGREES)N latitude had some degree of winter injury to branch tips.