Linked Life Data

12770844

Source:http://linkedlifedata.com/resource/pubmed/id/12770844

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
2003-5-28
pubmed:abstractText
It has been theorized that photosynthetic radiation use efficiency (PhRUE) over the course of a day is constant for leaves throughout a canopy if leaf nitrogen content and photosynthetic properties are adapted to local light so that canopy photosynthesis over a day is optimized. To test this hypothesis, 'daily' photosynthesis of individual leaves of Solanum melongena plants was calculated from instantaneous rates of photosynthesis integrated over the daylight hours. Instantaneous photosynthesis was estimated from the photosynthetic responses to photosynthetically active radiation (PAR) and from the incident PAR measured on individual leaves during clear and overcast days. Plants were grown with either abundant or scarce N fertilization. Both net and gross daily photosynthesis of leaves were linearly related to daily incident PAR exposure of individual leaves, which implies constant PhRUE over a day throughout the canopy. The slope of these relationships (i.e. PhRUE) increased with N fertilization. When the relationship was calculated for hourly instead of daily periods, the regressions were curvilinear, implying that PhRUE changed with time of the day and incident radiation. Thus, linearity (i.e. constant PhRUE) was achieved only when data were integrated over the entire day. Using average PAR in place of instantaneous incident PAR increased the slope of the relationship between daily photosynthesis and incident PAR of individual leaves, and the regression became curvilinear. The slope of the relationship between daily gross photosynthesis and incident PAR of individual leaves increased for an overcast compared with a clear day, but the slope remained constant for net photosynthesis. This suggests that net PhRUE of all leaves (and thus of the whole canopy) may be constant when integrated over a day, not only when the incident PAR changes with depth in the canopy, but also when it varies on the same leaf owing to changes in daily incident PAR above the canopy. The slope of the relationship between daily net photosynthesis and incident PAR was also estimated from the photosynthetic light response curve of a leaf at the top of the canopy and from the incident PAR above the canopy, in place of that measured on individual leaves. The slope (i.e. net PhRUE) calculated in this simple way did not differ statistically from that calculated using data from individual leaves.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0305-7364
pubmed:author
pubmed:issnType
Print
pubmed:volume
91
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
869-77
pubmed:dateRevised
2009-10-19
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Estimating photosynthetic radiation use efficiency using incident light and photosynthesis of individual leaves.
pubmed:affiliation
Istituto Sperimentale per l'Orticoltura, Via dei Cavalleggeri 25, 84098 Pontecagnano, (SA) Italy. adorosati@virgilio.it
pubmed:publicationType
Journal Article