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Photosynthetic down‐regulation over long‐term CO 2 enrichment in leaves of sour orange ( Citrus aurantium ) trees
Author(s) -
Adam Neal R.,
Wall Gerard W.,
Kimball Bruce A.,
Idso Sherwood B.,
Webber Andrew N.
Publication year - 2004
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.1469-8137.2004.01104.x
Subject(s) - photosynthesis , rubisco , biomass (ecology) , botany , orange (colour) , biomass partitioning , photosynthetic capacity , horticulture , chemistry , agronomy , biology
Summary• Understanding how trees are affected by a long‐term increase in atmospheric CO 2 is crucial to understanding the future impact of global climate change. Measurements of photosynthetic characteristics were made in sour orange trees ( Citrus aurantium ) growing under an enhanced CO 2 atmosphere and N‐replete soil for 14 yr to determine whether photosynthetic down‐regulation had occurred. • Photosynthesis, A : C i gas exchange relationships and Rubisco activity and content were measured throughout the 14th year of the experiment. The CO 2 ‐induced enhancement ratio of photosynthesis was calculated and compared with estimates of the enhancement of cumulative wood biomass production. • Content of the large subunit of Rubisco was significantly reduced by CO 2 enrichment indicating that down‐regulation had occurred. A high correlation between the CO 2 ‐induced enhancement of photosynthesis and the enhancement of cumulative wood biomass production suggested that the decline in wood biomass production was closely related to the decline in photosynthesis. • These results indicate that long‐term CO 2 enrichment can result in photosynthetic down‐regulation in leaves of trees, even under nonlimiting N conditions.