Silicon isotope study on rice plants from the Zhejiang province, China

Silicon isotope compositions of 16 rice plants from the Zhejiang province were studied, and potential applications of silicon isotope study to agriculture and biogeochemistry were discussed. It is found that the SiO2 contents in ignited rice plant samples increased generally from roots, through SL (stem and leaves), to husks. Large and systematic silicon isotope fractionation was observed among different organs of individual rice plants. Their delta Si-30 values show a generally increasing trend from roots and SL, through husks, to grains, which can be explained by kinetic isotope fractionation in a Rayleigh process. A delta Si-30 value of 6.1 parts per thousand was obtained from two samples of rice grains, which is much greater than the highest value (3.4 parts per thousand) observed in terrestrial samples before. It is inferred that monosilicic acid is the major silicon-bearing component taken up by rice roots. Passive uptake of silicon is important for rice and evapotranspiration may be the major mechanism for the transportation and precipitation of silicon in rice plants. It is suggested that silicon isotope study has a potential application to agriculture and biogeochemistry. (c) 2005 Elsevier B.V All rights reserved.