Silicon Isotopic Fractionation by Banana (Musa spp.) Grown in a Continuous Nutrient Flow Device
The determination of the plant-induced Si-isotopic fractionation is a promising tool to better quantify their role in the continental Si cycle. Si-isotopic signatures of the different banana plant parts and Si source were measured, providing the isotopic fractionation factor between plant and source. Banana plantlets (Musa acuminata Colla, cv Grande Naine) were grown in hydroponics at variable Si supplies (0.08, 0.42, 0.83 and 1.66 mM Si). Si-isotopic compositions were determined on a multicollector plasma source mass spectrometer (MC-ICP-MS) operating in dry plasma mode. Results are expressed as δ29Si relative to the NBS28 standard, with an average precision of ± 0.08‰ (±2σD). The fractionation factor 29ε between bulk banana plantlets and source solution is −0.40 ± 0.11‰. This confirms that plants fractionate Si isotopes by depleting the source solution in 28Si. The intra-plant fractionation Δ29Si between roots and shoots amounts to −0.21 ± 0.08‰. Si-isotopic compositions of the various plant parts indicate that heavy isotopes discrimination occurs at three levels in the plant (at the root epidermis, for xylem loading and for xylem unloading). At each step, preferential crossing of light isotopes leaves a heavier solution, and produces a lighter solution. Si-isotopic fractionation processes are further discussed in relation with Si uptake and transport in plants. These findings have important implications on the study of continental Si cycle.
KeywordsMusa Phytolith Silicon Si cycle Si-isotopic fractionation Si transport in plant
Unable to display preview. Download preview PDF.
We are grateful to A. Iserentant, C. Givron, P. Populaire (UCL), L. Monin, N. Dahkani, H. Doutrelepont (MRAC), J. de Jong and N. Mattielli (ULB) for their technical and scientific support. We thank J. Proost and L. Reylandt (UCL) for the SEM. This manuscript has greatly benefited from the constructive comm ents of two anonymous reviewers. This work was supported by the FNRS research convention No. 2.4629.05 and by the “Fonds Spécial de Recherche” (FSR) 2005 of the “Université catholique de Louvain”. S.O. is supported by the “Fonds National de la Recherche Scientifique” (FNRS) of Belgium as a Research Fellow, D.C. by the Federal Belgian Science Policy, C.H. by the “Fonds pour la formation à la Recherche dans l’Industrie et dans l’Agriculture” (FRIA) of Belgium, and X.D. is a Research Associate of the FNRS. L.A. thanks the FNRS for its financial support in the frame of the FRFC project #2.4512.00.
- Cardinal D, Alleman LY, Dehairs F, Savoye N, Trull TW, André L (2005) Relevance of silicon isotopes to Si-nutrient utilization and Si-source assessment in Antarctic waters. Global Biogeochem Cycles 19:GB2007Google Scholar
- Cardinal D, Savoye N, Trull TW, Dehairs F, Kopczynska EE, Fripiat F, Tison J-L, André L (in press). Silicon isotopes in spring Southern Ocean diatoms: large zonal changes despite homogeneity among size fractions. Mar ChemGoogle Scholar
- Carignan J, Cardinal D, Eisenhauer A, Galy A, Rehkämper M, Wombacher F, Vigier N (2004) A reflection on Mg, Cd, Ca, Li and Si isotopic measurements and related reference materials. Geostand Geoanal Res 28:139–148Google Scholar
- Ding T, Wan D, Wang C, Zhang F (2003) Large and systematic silicon isotope fractionation discovered in single sticks of bamboo. Goldschmidt Conf. Abstracts, A79Google Scholar
- Geis JW (1978) Biogenic opal in three species of gramineae. Ann Bot 42:1119–1129Google Scholar
- Lahav E (1995) Banana nutrition. In Gowen S (ed) Bananas and plantains. Chapman and Hall, London, pp 258–316Google Scholar
- Ma J F, Takahashi E (2002) Soil, fertilizer, and plant silicon research in Japan. Elsevier, AmsterdamGoogle Scholar
- Ma JF, Miyake Y, Takahashi E (2001) Silicon as a beneficial element for crop plants. In Datnoff LE, Snyder GH, Korndörfer GH (eds) Silicon in agriculture. Elsevier, The Netherlands, pp 17–39Google Scholar
- Raven JA (1983) The transport and function of silicon plants. Biol Rev 58:179–207Google Scholar
- Robinson JC (1995) Systems of cultivation and management. In: Gowen S (ed). Bananas and plantains. Chapman and Hall, London, pp 15–65Google Scholar
- Sangster AG, Hodson MJ (1986) Silica in higher plants. In: Evered D, Oȁ9Connon M (ed) Silicon biogeochemistry. J. Wiley, Chichester, pp 90–107Google Scholar
- Sangster AG, Parry DW (1981) Ultrastructure of silicon deposits in higher plants. In Simpson TL, Volcani BE (eds). Silicon and siliceous structures in biological systems. Springer-Verlag, New York, pp 383–407Google Scholar
- Stumm W, Morgan JJ (1996) Aquatic chemistry—chemical equilibria and rates in natural waters (ed). J. Wiley and sons. New York. 1022 ppGoogle Scholar
- Takahashi K, Ma JF, Miyake Y (1990) The possibility of silicon as an essential element for higher plants. Comment Agr Food Chem 2:99–122Google Scholar
- Tomlinson PB (1969) Anatomy of the monocotyledons III Commelinales-Zingiberales. Clarendon Press, OxfordGoogle Scholar