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Photosynthesis, immediate export and carbon partitioning in source leaves of C 3 , C 3 ‐C 4 intermediate, and C 4 Panicum and Flaveria species at ambient and elevated CO 2 levels
Author(s) -
Leonardos E. D.,
Grodzinski B.
Publication year - 2000
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.2000.00604.x
Subject(s) - photosynthesis , panicum , starch , botany , biology , chemistry , food science
Immediate export in leaves of C 3 ‐C 4 intermediates were compared with their C 3 and C 4 relatives within the Panicum and Flaveria genera. At 35 Pa CO 2 , photosynthesis and export were highest in C 4 species in each genera. Within the Panicum , photosynthesis and export in ‘type I’ C 3 ‐C 4 intermediates were greater than those in C 3 species. However, ‘type I’ C 3 ‐C 4 intermediates exported a similar proportion of newly fixed 14 C as did C 4 species. Within the Flaveria , ‘type II’ C 3 ‐C 4 intermediate species had the lowest export rather than the C 3 species. At ambient CO 2 , immediate export was strongly correlated with photosynthesis. However, at 90 Pa CO 2 , when photosynthesis and immediate export increased in all C 3 and C 3 ‐C 4 intermediate species, proportionally less C was exported in all photosynthetic types than that at ambient CO 2 . All species accumulated starch and sugars at both CO 2 levels. There was no correlation between immediate export and the pattern of 14 C‐labelling into sugars and starch among the photosynthetic types within each genus. However, during CO 2 enrichment, C 4 Panicum species accumulated sugars above the level of sugars and starch normally made at ambient CO 2 , whereas the C 4 Flaveria species accumulated only additional starch.