Journal Article

Seasonal changes in photosynthesis, nitrogen content and nitrogen partitioning in <i>Lindera umbellata</i> leaves grown in high or low irradiance

Yuko Yasumura, Kouki Hikosaka and Tadaki Hirose

in Tree Physiology

Volume 26, issue 10, pages 1315-1323
Published in print October 2006 | ISSN: 0829-318X
Published online October 2006 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/26.10.1315
Seasonal changes in photosynthesis, nitrogen content and nitrogen partitioning in Lindera umbellata leaves grown in high or low irradiance

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Seasonal changes in photosynthetic capacity, leaf nitrogen (N) content and N partitioning were studied from before leaf maturation (spring) until death (autumn) in high- and low-light-exposed leaves of a deciduous shrub, Lindera umbellata var. membranacea (Maxim.) Momiyama growing in a natural forest in northeast Japan. In spring, light-saturated photosynthetic rate (Pmax) was low despite high leaf N and Rubisco contents, indicating that the photosynthetic apparatus was not yet functionally developed. Rubisco seemed to be only partially active. In summer and autumn, Pmax per unit leaf N increased and changes in Pmax were correlated with changes in leaf N and two photosynthetic components, Rubisco and chlorophyll. Changes in these components paralleled the changes in leaf N. During leaf senescence, about 70% of leaf N was resorbed. Metabolic proteins that accounted for the majority of leaf N in summer were highly degradable and more than sufficient to explain the high N-resorption efficiency. Structural proteins represented only a small part of leaf N and were relatively resistant to degradation and thus contributed little to N resorption. Leaf N partitioning between metabolic and structural proteins determined the amount of retranslocatable N, but did not strictly determine the N content of a dead leaf or N-resorption efficiency.

Keywords: chlorophyll; dead leaf; leaf mass per area; leaf senescence; metabolic protein; nitrogen resorption; Rubisco; structural protein

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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