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Role of carbohydrate supply in white and brown root respiration of ponderosa pine
Author(s) -
Lipp Cynthia C.,
Andersen Christian P.
Publication year - 2003
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 - 10.1046/j.1469-8137.2003.00914.x
Subject(s) - respiration , shoot , respiratory quotient , botany , darkness , carbohydrate , chemistry , horticulture , photosynthesis , zoology , respiration rate , soil respiration , biology , biochemistry
Summary• Respiration of intact ponderosa pine ( Pinus ponderosa ) fine roots (< 2.5 mm) was measured to determine the role of recently fixed carbohydrate in maintaining root metabolism of growing white (WR) and recently suberized brown roots (BR). • The CO 2 efflux and O 2 uptake of individual roots were followed continuously over 24 h after carbohydrate supply was altered by exposing shoots to light/dark treatments and by root excision. • In situ respiration of individual WR and BR averaged 86.0 ± 2.6 and 21.1 ± 1.5 mol CO 2 g −1 h −1 , respectively. Growth respiration was estimated to be approximately two‐thirds the rate of WR respiration. Attached WR and BR respiration did not decline significantly over 24 h under continuous light. The WR respiration significantly decreased during a dark period. All roots maintained relatively constant respiration rates for at least 6 h after excision. Respiratory quotient (RQ; CO 2 : O 2 ) was not different between attached (0.84 ± 0.014) and detached (0.85 ± 0.017) roots. CO 2 environment of the cuvette did not influence WR or BR respiration. • The WR appear to be more sensitive to supply of current photosynthate than BR. Shoot light environment needs to be considered when measuring root and soil CO 2 efflux.