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THE INFLUENCE OF LEAVES ON COTYLEDON PHOTOSYNTHESIS AND EXPORT DURING SEEDING DEVELOPMENT IN ACER
Author(s) -
AMPOFO S. T.,
MOORE K. G.,
LOVELL P. H.
Publication year - 1976
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1976.tb01458.x
Subject(s) - cotyledon , hypocotyl , photosynthesis , seedling , acer pseudoplatanus , biology , botany
SUMMARY The photosynthetic contributions of the cotyledons and of leaf pair one to seedling growth of Acer and the interactions between them were studied using 14 CO 2 . During early development the cotyledons of A. negundo, A. platanoides and A. pseudoplatanus exported photosynthates to the hypocotyl, roots and young expanding leaves. When the first pair of leaves began to export photosynthate, export from the cotyledons declined in A. negundo and A. pseudoplatanus and was directed increasingly to the roots and hypocotyl. As further leaf pairs were produced, the movement of photosynthates from the first leaf pair became increasingly basipctal (as occurred at an earlier stage for the cotyledons). The decline in total fixation in, and percentage export from, cotyledons of A. negundo and A. pseudoplatanus was shown to be due to the increase in other sources of photosynthesis (leaves) and a consequent reduction in the demand for cotyledon photosynthetic products. Removal of the expanded leaves resulted in an increase in cotyledon fixation and export and also a rapid, marked change in the direction of export. Thus, the cotyledons maintained a high potential for photosynthesis although this was realized later in seedling development only if other sources of photosynthetic products were removed. A. platanoides differed from the other two species in that there was an increase in export from both cotyledons and leaf pair one about 30 days after seedling emergence, coinciding with the production of leaf pairs two and three. Presumably these constituted a major sink which created a greater demand for photosynthetic products, thereby increasing fixation and export rates of the photosynthetic organs present.