Notes: Specific Gravity Variation in a Loblolly Pine Seed Source Study in the Western Gulf Region
Specific gravity in 28 plantings of the Western Gulf Forest Tree Improvement Program seed source study varied by provenance, family within provenance, and test location. Trees from south Arkansas had the highest specific gravity (0.424) while those from south Louisiana had the lowest (0.398). Southeast Texas and north Louisiana trees were intermediate with an average specific gravity of 0.405. Trees from a North Carolina coastal source had the lowest specific gravity in the five plantings in Arkansas and Oklahoma in which they were included. Families generally ranked the same in all tests. This implied that specific gravity was under strong genetic control and genotype by environment interaction was not operationally meaningful. However, specific gravity was environmentally sensitive as it varied significantly among locations. Environmental and genetic patterns of variation did not agree; therefore, in situ studies of regional specific gravities should not be used for making seed movement decisions. For. Sci. 34(3):798-803.
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