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

Journal Article · Fri Jun 01 04:00:00 EDT 1979 · For. Sci.; (United States)

OSTI ID:5151029

McLaughlin, S B; McConathy, R K; Beste, B

Seasonal changes in photosynthate translocation and allocation of two mature, co-dominant 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-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%), greatly reduced by day 4, and ranged from 63 to 91% by day 7. Maximum retention of initial activity levels occurred in April for leaves (44%) and in October for branches (15%). 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% in April, 30% in June, and 60% in October. These results indicate that canopy growth and maintenance impose a significant drain on availability of photosynthate throughout the growing season.

• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5151029
• Journal Information: For. Sci.; (United States), Journal Name: For. Sci.; (United States) Vol. 25:2; ISSN FOSCA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DISTRIBUTION
GROWTH
LABELLED COMPOUNDS
LEAVES
OAKS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANT GROWTH
PLANTS
SEASONAL VARIATIONS
SYNTHESIS
TISSUE DISTRIBUTION
TREES
VARIATIONS