Photosynthetic induction state of leaves in a soybean canopy in relation to light regulation of ribulose-1-5-bisphosphate carboxylase and stomatal conductance

Photosynthetic induction state, stomatal conductance and light regulation of ribulose-1,5-bisphosphate carboxylase (rubisco) were examined for leaves in a mature, closed soybean (Glycine max) canopy (leaf area index approximately 5) with the objective to determine the extent to which these factors m...

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Published inPlant physiology (Bethesda) Vol. 94; no. 2; pp. 628 - 633
Main Authors Pearcy, R.W. (University of California, Davis, CA), Seemann, J.R
Format Journal Article
LanguageEnglish
Published United States American Society of Plant Physiologists 01.10.1990
Subjects
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
COUVERT
CUBIERTA DE COPAS
ESTOMA
FEUILLE
Forest canopy
FOTOSINTESIS
GLYCINE MAX
HOJAS
Leaves
LIASAS
LUMIERE
LUZ
LYASE
NEVADA
Photons
PHOTOSYNTHESE
Photosynthesis
Physiological regulation
Plants
Soybeans
Stomatal conductance
STOMATE
Sunlight
TRANSPIRACION
TRANSPIRATION
Vegetation canopies
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Summary:Photosynthetic induction state, stomatal conductance and light regulation of ribulose-1,5-bisphosphate carboxylase (rubisco) were examined for leaves in a mature, closed soybean (Glycine max) canopy (leaf area index approximately 5) with the objective to determine the extent to which these factors may be limiting the capacity to respond to light transients during sunflecks. When sampled along a vertical gradient, leaves near the bottom of the canopy had lower rubisco contents and chlorophyll a/b ratios as compared with upper leaves. Leaves sampled at midcanopy showed a wide variation in photosynthetic induction state (ratio of the photosynthetic rate achieved after 1 minute exposure to high light to the steady-state assimilation rate achieved after 20 minutes exposure). Both photosynthetic induction state and the initial rubisco activity varied in parallel with stomatal conductance. By contrast there was no correlation between total rubisco activity and stomatal conductance. The results indicate that induction state, as determined by the light regulation of both rubisco activity and stomatal conductance, is an important limitation to the ability of leaves in a soybean canopy to respond to light transients that occur during sunflecks
Bibliography:F60
9109039
ObjectType-Article-1
SourceType-Scholarly Journals-1
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content type line 23
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.94.2.628