Realized Genetic Gains for First Generation Improved Loblolly Pine in 45 Tests in Coastal North Carolina
Abstract:An improved first generation check (a mixture of 12 of the best open-pollinated families) was compared with an unimproved check in 45 tests in coastal North Carolina at age 6 or 7 yr. Excellent and consistent genetic gains were realized for exhibited site index and sweep reduction from the first generation of genetic improvement. It was rare that the unimproved check lot was better than the first generation improved stock for site index (2 out of 45 trials) or stem sweep (1 out of 45 trials). On average, a 3.4 ft improvement in exhibited site index (3.9%) and a 0.43 in. reduction in sweep (-27%) were realized across all tests, both highly statistically significant. Moderate but statistically significant gains in rust resistance were realized. Rust resistance gains were moderate because rust is not a serious problem in the region, and less emphasis was given to rust resistance in the selection of families than to growth rate and stem straightness. Improvements in survival through age six were nominal and statistically nonsignificant since survival was not a primary selection criterion in this region where survival is generally good. Regressions of improved check means by site were regressed onto unimproved check means for a better understanding of the nature of realized gains for the various traits. South J. Appl. For. 24(3):140-144.
Document Type: Journal Article
Affiliations: Weyerhaeuser Company, 810 Whittington Ave., Hot Springs, AR 71901, (501) 624-8510
Publication date: August 1, 2000
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- Each regional journal of applied forestry focuses on research, practice, and techniques targeted to foresters and allied professionals in specific regions of the United States and Canada. The Southern Journal of Applied Forestry covers an area from Virginia and Kentucky south to as far west as Oklahoma and east Texas.
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