Seasonal changes in within-canopy allocation of /sup 14/C-photosynthate by white oak

Journal Article · Mon Jan 01 04:00:00 EST 1979 · For. Sci.; (United States)

OSTI ID:5634154

McLaughlin, S B ^[1]; McConathy, R K; Beste, B

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1. Oak Ridge National Lab., TN

Seasonal changes in photosynthate translocation and allocation of two mature, codominant white oak trees were studied by following rates of movement of /sup 14/C-photosynthate from foliage labeled with /sup 14/CO/sub 2/. Loss rates were determined by sampling foliage at 5 min and 1, 4, and 7 days after labeling on each of five dates (April 22 to October 4). Incorporation of /sup 14/C-photosynthate into 1-, 3-, and 5-year-old branches was determined 7 days after tagging. Losses of /sup 14/C from leaves were rapid by day 1 (less than or equal to 80 percent), greatly reduced by day 4, and ranged fom 63 to 91 percent by day 7. Maximum retention of initial activity levels occurred in April for leaves (44 percent) and in October for branches (15 percent). Approximately equal apportionment of activity between leaves and branches did not occur until August. Highest total retention of photosynthate in the canopy occurred in April (due to high incorporation in leaves) and June (due to high retention in both leaves and branches). Based on measured retention and estimated respiration losses, translocation of the original /sup 14/C-photosynthate from the canopy was calculated to be approximately 0 percent in April, 30 percent in June, and 60 percent in October. These results indicate that canopy growth and maintenance impose a significant drain on availability of photosynthate throughout the growing season.

• OSTI ID: 5634154
• Journal Information: For. Sci.; (United States), Journal Name: For. Sci.; (United States) Vol. 25:2; ISSN FOSCA
• Country of Publication: United States
• Language: English

Related Subjects

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59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON 14
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON ISOTOPES
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
EVEN-EVEN NUCLEI
ISOTOPES
LEAVES
LIGHT NUCLEI
NUCLEI
OAKS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANTS
RADIOISOTOPES
RESPIRATION
RETENTION
SEASONAL VARIATIONS
SYNTHESIS
TRANSLOCATION
TREES
VARIATIONS
YEARS LIVING RADIOISOTOPES