Journal Article

Leaf gas exchange, chlorophyll fluorescence and pigment indexes of <i>Eugenia uniflora</i> L. in response to changes in light intensity and soil flooding

Marcelo S. Mielke and Bruce Schaffer

in Tree Physiology

Volume 30, issue 1, pages 45-55
Published in print January 2010 | ISSN: 0829-318X
Published online November 2009 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/tpp095
Leaf gas exchange, chlorophyll fluorescence and pigment indexes of Eugenia uniflora L. in response to changes in light intensity and soil flooding

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The interactive effects of changing light intensity and soil flooding on the photosynthetic performance of Eugenia uniflora L. (Myrtaceae) seedlings in containers were examined. Two hypotheses were tested: (i) the photosynthetic apparatus of shade-adapted leaves can be rapidly acclimated to high light after transfer from shade to full sun, and (ii) photosynthetic acclimation to changing light intensity may be influenced by soil flooding. Seedlings cultivated in a shade house (40% of full sun, ≈ 12 mol m2 day1) for 6 months were transferred to full sun (20–40 mol m−2 day−1) or shade (30% of full sun, ≈ 8 mol m−2 day−1) and subjected to soil flooding for 23 days or not flooded. Chlorophyll content index (CCI), chlorophyll fluorescence, leaf weight per area (LWA), photosynthetic light–response curves and leaf reflectance indexes were measured during soil flooding and after plants were unflooded. The CCI values increased throughout the experiment in leaves of shaded plants and decreased in leaves of plants transferred to full sun. There were no significant interactions between light intensity and flooding treatments for most of the variables analyzed, with the exception of Fv/Fm 22 days after plants were flooded and 5 days after flooded plants were unflooded. The light environment significantly affected LWA, and light environment and soil flooding significantly affected the light-saturated gross CO2 assimilation rate expressed on area and dry weight bases (Amax-area and Amax-wt, respectively), stomatal conductance of water vapor (gssat) and intrinsic water use efficiency (A/gs). Five days after flooded plants were unflooded, the normalized difference vegetation index (NDVI) and the scaled photochemical reflectance index (sPRI) were significantly higher in shade than in sun leaves. Thirty days after transferring plants from the shade house to the light treatment, LWA was 30% higher in sun than in shade leaves, and Amax-area and gssat were 59% and 99% higher, respectively, in shade than in sun leaves. Changes in CCI, NDVI and sPRI in leaves of E. uniflora seedlings transferred from shade to full sun appear to be associated with changes in pigment composition and protective mechanisms against excess light.

Keywords: chlorophyll content index; leafweight per area; Myrtaceae; photosynthetic acclimation; reflectance indexes

Journal Article.  8133 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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