Role of carbohydrate supply in white and brown root respiration of ponderosa pine

• Published in: The New phytologist Vol. 160; no. 3; pp. 523 - 531
• Main Authors: Lipp, Cynthia C., Andersen, Christian P.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science 01.12.2003; Blackwell Publishing Ltd; Blackwell
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; carbohydrates; Carbon dioxide; diurnal variation; Economic plant physiology; forest trees; Fundamental and applied biological sciences. Psychology; light; light response; Metabolism; Net assimilation, photosynthesis, carbon metabolism. Photorespiration, respiration, fermentation (anoxia, hypoxia); Nutrition. Photosynthesis. Respiration. Metabolism; oxygen; photorespiration; Photosynthesis, respiration. Anabolism, catabolism; Pine trees; Pinus ponderosa; Plant physiology and development; Plant roots; Plants; ponderosa pine (Pinus poderosa); Respiration; root excision; Root growth; root hairs; root respiration; Seedlings; Soil ecology; Soil respiration; Tree physiology; Light effect; root excision; Root; Growth; Resource allocation; Carbon dioxide; Supply; Environmental factor; Metabolism; root respiration; Pinus ponderosa; Light; light response; Softwood forest tree; Gymnospermae; Coniferales; Spermatophyta; Carbohydrate; Developmental stage; ponderosa pine (Pines poderosa); Gas exchange; Suberization; Respiration; ponderosa pine (Pinus poderosa)
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1046/j.1469-8137.2003.00914.x

• 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 CO2 efflux and O2 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 μmol CO2 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; CO2: O2) was not different between attached (0.84 ± 0.014) and detached (0.85 ± 0.017) roots. CO2 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 CO2 efflux.