Journal Article

Water relations and photosynthetic capacity of two species of <i>Calotropis</i> in a tropical semi-arid ecosystem

Wilmer Tezara, Rita Colombo, Ilsa Coronel and Oranys Marín

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 107, issue 3, pages 397-405
Published in print March 2011 | ISSN: 0305-7364
Published online December 2010 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcq245
Water relations and photosynthetic capacity of two species of Calotropis in a tropical semi-arid ecosystem

More Like This

Show all results sharing these subjects:

  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

Background and Aims

Calotropis procera and Calotropis gigantea, originally from warm parts of Africa and Asia, are now pan-tropical and in ecological terms considered an indicator of overgrazed, disturbed lands; they grow successfully in dry areas. Variations in water relations, morphology and photosynthesis of the two species growing in the same habitat were studied to assess possible mechanisms of tolerance to drought and how these relate to their ecophysiological success. Also the hypothesis that their photosynthetic rate (A) under drought would be affected by stomatal and non-stomatal limitations was tested.

Methods

Water relations, gas exchange, water use efficiency (WUE), fluorescence parameters, pubescence and specific leaf area (SLA) of Calotropis procera and C. gigantea plants growing in the field were evaluated during the wet (WS) and dry (DS) seasons.

Results

The xylem water potential (ψ) was similar in both species during the WS and DS; drought caused a 28 % decrease of ψ. In C. procera, A, stomatal conductance (gs) and carboxylation efficiency (CE) were higher in the WS with half the values of those during the DS, this species being more affected by drought than C. gigantea. A high δ13C of C. gigantea (–26·2 ‰) in the WS indicated a higher integrated WUE, in agreement with its lower gs. Leaves of C. gigantea were more pubescent than C. procera. Relative stomatal and non-stomatal limitation of A increased with drought in both species; no changes in maximum quantum yield of photosystem II (PSII; Fv/Fm) were observed. The decrease in the relative quantum yield of PSII (φPSII) and in the photochemical quenching coefficient (qP) was more pronounced in C. procera than in C. gigantea.

Conclusions

The photosynthetic capacity of C. procera was higher than that of C. gigantea. During the DS, A was regulated by stomatal and non-stomatal factors in a coordinated manner and drought did not cause chronic photoinhibition. A higher density of trichomes and leaf angle in C. gigantea may contribute to the maintenance of A and confer more efficient protection of photochemical activity in the DS. Ecophysiological traits such as high photosynthetic rate throughout the year even during the DS, and high WUE, highly pubescent leaves and low SLA observed in both species contribute to the establishment and growth of Calotropis in dry conditions.

Keywords: Photosynthesis; Calotropis procera; Calotropis gigantea; fluorescence; non-stomatal limitation; stomatal limitation; drought

Journal Article.  6749 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.