Details

Autor(en) / Beteiligte

• Wertin, Timothy M
• Teskey, Robert O

Titel

Close coupling of whole-plant respiration to net photosynthesis and carbohydrates

Ist Teil von

• Tree physiology, 2008-12, Vol.28 (12), p.1831-1840

Ort / Verlag

Canada: Heron Publishing

Erscheinungsjahr

2008

Quelle

MEDLINE

Beschreibungen/Notizen

• We studied the effect of changes in net photosynthesis (A(net)) on respiration, soluble sugars and carbohydrates in Populus deltoides Bartr. ex Marsh. saplings under controlled environmental conditions by making daily measurements of leaf respiration (R(d)), stem CO2 efflux and root CO2 efflux at a constant temperature in growth chambers. After a pretreatment period, one of three treatments was applied for 5 to 7 days: (1) increased atmospheric CO2 concentration; (2) decreased photoperiod and photosynthetic photon flux (PPF); or (3) continuous darkness. Increased Anet in response to elevated CO2 concentration resulted in a sustained increase in whole-plant respiration, with R(d) increasing 46%, stem CO2 efflux increasing 130% and root CO2 efflux increasing 16%. Elevated CO2 concentration also caused a significant increase in leaf soluble sugars. Decreasing photoperiod and PPF or complete darkness caused a rapid decrease in respiration throughout the saplings. In the low light treatment, R(d) decreased 40%, stem CO2 efflux decreased 78%, root CO2 efflux decreased 74% and significant decreases in leaf and root soluble sugar and leaf nonstructural carbohydrate concentrations were observed. Continuous darkness resulted in a 70% decrease in R(d), a 65% decrease in stem CO2 efflux, a 73% decrease in root CO2 efflux and significant decreases in leaf and root soluble sugar and root carbohydrate concentrations. In all treatments, changes in respiration rates in all tissues occurred within hours of treatment application. In addition, a diurnal pattern in root CO2 efflux was observed throughout the experiment under constant environmental conditions. The observed rapid changes in whole-plant respiration following treatment application and the diurnal patterns in root CO2 efflux suggest that growth and maintenance respiration in the saplings was strongly dependent on newly acquired carbohydrates.