We studied the effect of changes in net photosynthesis (A(net)) on respiration, soluble @entity3363 and @entity3363 in Populus deltoides Bartr. ex Marsh. saplings under controlled environmental conditions by making daily measurements of leaf respiration (R(d)), stem @entity515 efflux and root @entity515 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 @entity515 concentration; (2) decreased photoperiod and photosynthetic photon flux ( @entity2848 ); or (3) continuous darkness. Increased A(net) in response to elevated @entity515 concentration resulted in a sustained increase in whole-plant respiration, with R(d) increasing 46%, stem @entity515 efflux increasing 130% and root @entity515 efflux increasing 16%. Elevated @entity515 concentration also caused a significant increase in leaf soluble @entity3363 . 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 @entity515 efflux decreased 78%, root @entity515 efflux decreased 74% and significant decreases in leaf and root soluble sugar and leaf nonstructural @entity1735 concentrations were observed. Continuous darkness resulted in a 70% decrease in R(d), a 65% decrease in stem @entity515 efflux, a 73% decrease in root @entity515 efflux and significant decreases in leaf and root soluble sugar and root @entity1735 concentrations. In all treatments, changes in respiration rates in all tissues occurred within hours of treatment application. In addition, a diurnal pattern in root @entity515 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 @entity515 efflux suggest that growth and maintenance respiration in the saplings was strongly dependent on newly acquired @entity3363 .

Close coupling of whole-plant respiration to net photosynthesis and XXXX .

@entity2848 :: ('CHEBI:50459', 'Chemical') :: ['PPF'] @entity3363 :: ('MESH:D002241', 'Chemical') :: ['sugars', 'carbohydrates'] @entity1735 :: ('CHEBI:16646', 'Chemical') :: ['carbohydrate'] @entity515 :: ('CHEBI:29334', 'Chemical') :: ['CO(2)']
@entity3363 :: (MESH:D002241,Chemical) :: ['carbohydrates']
