Journal Article

Role of transitory carbon reserves during adjustment to climate variability and source–sink imbalances in oil palm (<i>Elaeis guineensis</i>)

S. Legros, I. Mialet-Serra, A. Clement-Vidal, J.-P. Caliman, F.A. Siregar, D. Fabre and M. Dingkuhn

in Tree Physiology

Volume 29, issue 10, pages 1199-1211
Published in print October 2009 | ISSN: 0829-318X
Published online October 2009 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/tpp057
Role of transitory carbon reserves during adjustment to climate variability and source–sink imbalances in oil palm (Elaeis guineensis)

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Oil palm (Elaeis guineensis Jacq.) is a perennial, tropical, monocotyledonous plant characterized by simple architecture and low phenotypic plasticity, but marked by long development cycles of individual phytomers (a pair of one leaf and one inflorescence at its axil). Environmental effects on vegetative or reproductive sinks occur with various time lags depending on the process affected, causing source–sink imbalances. This study investigated how the two instantaneous sources of carbon assimilates, CO2 assimilation and mobilization of transitory non-structural carbohydrate (NSC) reserves, may buffer such imbalances. An experiment was conducted in Indonesia during a 22-month period (from July 2006 to May 2008) at two contrasting locations (Kandista and Batu Mulia) using two treatments (control and complete fruit pruning treatment) in Kandista. Measurements included leaf gas exchange, dynamics of NSC reserves and dynamics of structural aboveground vegetative growth (SVG) and reproductive growth. Drought was estimated from a simulated fraction of transpirable soil water. The main sources of variation in source–sink relationships were (i) short-term reductions in light-saturated leaf CO2 assimilation rate (A max) during seasonal drought periods, particularly in Batu Mulia; (ii) rapid responses of SVG rate to drought; and (iii) marked lag periods between 16 and 29 months of environmental effects on the development of reproductive sinks. The resulting source–sink imbalances were buffered by fluctuations in NSC reserves in the stem, which mainly consisted of glucose and starch. Starch was the main buffer for sink variations, whereas glucose dynamics remained unexplained. Even under strong sink limitation, no negative feedback on A max was observed. In conclusion, the different lag periods for environmental effects on assimilate sources and sinks in oil palm are mainly buffered by NSC accumulation in the stem, which can attain 50% (dw:dw) in stem tops. The resulting dynamics of growth and production are complex because several dozen phytomers of different phenological ages develop at any given time and interact with a common pool of reserves.

Keywords: carbon assimilation; glucose; growth; non-structural carbohydrates; phenotypic plasticity; source–sink relationships; starch

Journal Article.  8062 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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