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Genetic variation in carbon isotope discrimination, respiratory metabolism, growth, bud phenology, and their interrelationships among seedlings of two Douglas-fir varieties and their F2 hybrid progeny.
Smith, Bruce *,1, Anekonda, Thimmappa2, Jones, Clayton1, Keller, Emily1, Hansen, Lee1, 1 Brigham Young University, Provo, Utah, USA2 Oregon State Univeresity, Corvallis, Oregon, USA
ABSTRACT- In a common garden study, seedlings of Psuedotsuga menziessii (Douglas-fir) var. menziessii (coastal) from Lacomb, Oregon and var. glauca (interior) from Clearwater National Forest, Idaho and their F2 hybrids were grown in nursery beds in order to understand the genetic variability in growth and phenology traits of segregating hybrids relative to their parents. Height, stem diameter, and bud burst percent were measured in May 1999. Metabolic heat rate and respiration rate were measured on the apical meristems at 30, 35, and 40oC. The tissue was then dried overnight in a vacuum oven, ground, combusted and analyzed for carbon isotopic ratios. The coastal variety was from an elevation of 245 m with a mean annual rainfall of 1,400 mm. The interior variety was from an elevation of 871 m and a mean annual rainfall of 600 mm. The two varieties differed from one another in growth traits, bud burst, carbon isotopic values and respiration measurements. The F2 hybrid progeny had similar isotopic values to the interior variety and differed significantly from the coastal variety. However respiration measurements of the hybrids were similar to the coastal variety. Few trait differences between families were noted. The fast growing coastal variety showed the least carbon isotope discrimination relative to the slow growing and presumably more stressed interior variety.
Key words: calorespirometry, Douglas-fir, carbon isotopes, adaptation