Treesearch

In southern Michigan, the winter of 1976-1977 was marked by unseasonably cold weather in early December, prolonged cold weather in December and January, severe drought at the onset of cold weather, and by higher than average absolute minimum temperatures. Damage, presumably from the early December cold weather, was severe to southern seedlots of ponderosa pine, Austrian pine from the western Mediterranean, Cryptomeria, spanish origin Scotch pines planted in low-lying areas, and southern seedlots of white fir. Surprisingly, there was little damage to eastern white pine from the southern...

A reciptrocal crossing program of Picea glauca and P. omorika, and P. mariana and P. omorika with adequate intraspecific control crosses was carried out. Yields of full seed/cone ranged from 0 to 2.6 for the P. glauca-P. omorika combination. These low seed sets and a 9-day difference in female receptivity rule out producing this hybrid via seed. The full seed/cone yields of the P. mariana-P. omorika combinations averaged approximately half the yield of the intraspecific crosses. However, receptivity of the two species is well synchronized and in spite of reduced yields, mass production via...

Surging demands for wood fiber that must be produced on a decreasing acreage of forest land suggest soaring prices, a shrinking market for wood products, or both. Either of these consequences can be forestalled or prevented by implementing existing technologies, one of which is cultivation of genetically improved trees. Multiple and sizable gains from improved trees are likely. Gains are not without risks, however, as possible losses may occur through failure to accumulate capital necessary to establish plantations of improved trees on good sites.

Ten traits were measured on 10-year-old jack pine grown at Cloquet, Minnesota, from seed collected from 90 provenances. The traits were examined by using analysis of variance and computing correlations for all combinations of 9 traits plus latitude , longitude, and elevation of the seed sources and cluster analyses using the D2 values from the Mahalanobis distance function. Results of the ANOVA showed that seed sources differed greatly for the 10 traits measured and results of the cluster analysis showed that populations can be geographically defined.

Seed production in southern pine seed orchards can be evaluated by estimating the efficiency of four separate stages of cone, seed, and seedling development. Calculated values are: cone efficiency (CE), the ratio of mature cones to the initial flower crop; seed efficiency (SE), the ratio of filled seeds per cone to the seed potential; extraction efficiency (EE), the ratio of extracted seeds per cone to the total seeds; and germination efficiency (GE), the ratio of germinated seeds per cone to the filled seeds. The product of these four efficiency values is the overall seed orchard to...

The Eastern Region, USDA Forest Service has been establishing and managing seed orchards to produce improved seed for the National Forests in the Lake States since 1969. This paper presents a review of the female flower production for the past 4 years in the white pine, white spruce, and black spruce clonal seed orchards.

Seed production and percent of natural selfing were determined in an 8 x 8-foot, 1200-tree plantation. Actual seed production was determined through age 6; production through age 8 was projected based on first-year cone counts at age 7. The percent of natural self-pollination, production of seedlings from natural selfing, and percent of selfs that were lethal were determined by marker seedlings. Ovulate strobili production began at 17 months of age; by age 4 a few trees produced small quantities of mature cones and seed. By age 8 years most trees produced an average of 39 mature cones per...

An outline of the general problems involved with the propagation of elite conifer clones by rooted cuttings is drawn from published reports. New approaches for resolving these problems can come from studies of clone production through tissue culture methods. Probable extension of tissue culture techniques will permit the establishment of clones from adult, proven trees and may also provide a tool for in vitro propagule evaluation of disease resistance.

The genetic and economic effects of two stages of truncation selection in a white spruce seedling orchard were investigated by computer simulation. Genetic effects were computed by assuming a bivariate distribution of juvenile and mature traits and volume was used as the selection criterion. Seed production was assumed to rise in a linear fashion to maturity and then remain constant for the life of the orchard. Expected seed production was used to compute the number of acres that could be planted and volume gain over this acreage was estimated using predicted response to selection and...

The effectiveness of gibberellins as promotors of flowering in Cupressaceae and Taxodiaceae is historically reviewed, emphasizing that these groups of plants respond to polar gibberellins and produce sexual structures after exogenous application of GA3. Species in Pinaceae, on the other hand, can be brought into flowering with non-polar gibberellin treatments. Admixtures of gibberellins applied with auxin and stimulatory cultural treatments such as strangulation, nitrate fertilization, root pruning, or drought stress are particularly successful. Each species, age, even each clone and each...