@article{hashimoto_smyth_israel_hesterberg_2010, title={LACK OF SOYBEAN ROOT ELONGATION RESPONSES TO MICROMOLAR MAGNESIUM ADDITIONS AND FATE OF ROOT-EXUDED CITRATE IN ACID SUBSOILS}, volume={33}, ISSN={["1532-4087"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-73149088156&partnerID=MN8TOARS}, DOI={10.1080/01904160903434279}, abstractNote={Additions of micromolar concentrations of magnesium (Mg) to hydroponics enhance aluminum (Al) tolerance of soybean by increasing citrate secretion from roots and external complexation of toxic Al species. The objective of this study was to assess the ameliorative effect of Mg additions on soybean root elongation into mineralogically different acid soils. Roots of soybean seedlings grew for 28 days into acid soils treated with three Mg levels in their soil solution (Control, 150 and 300 μM) and lime. Root growth in the acid soils and aboveground dry matter responses to the Mg treatments were less than for the lime treatments. Citrate fate in the acid soils revealed that 66–99% of added citrate was either adsorbed or biodegraded, suggesting that root secreting citrate in the soil abundant with Al and iron (Fe) hydroxides potentially reduces the availability to complex rhizotoxic Al. A calcium (Ca) deficiency may have constrained root growth response to the Mg-treated soils.}, number={2}, journal={JOURNAL OF PLANT NUTRITION}, author={Hashimoto, Yohey and Smyth, T. Jot and Israel, Daniel W. and Hesterberg, Dean}, year={2010}, pages={219–239} }
 @article{hashimoto_2007, title={Citrate sorption and biodegradation in acid soils with implications for aluminum rhizotoxicity}, volume={22}, ISSN={["0883-2927"]}, DOI={10.1016/j.apgeochem.2007.07.006}, abstractNote={Abstract Citrate and other organic acids play an important role in the rhizosphere and pedogenic processes. Although secreting citrate from roots in response to Al and heavy metal stress has been recognized as a central mechanism for plants to avoid toxicity, the efficiency of root citrate on metal detoxification is still contradictory in acid soil with abundant oxide minerals that serve as a potential sorption site for citrate. The objective of this study was to investigate sorption and biodegradation of citrate in subtropical acid soils with different mineralogical properties. A batch experiment was conducted to assess the possible fates (adsorption and biodegradation) of citrate in the three acid soils (Cecil, Creedmoor and Norfolk) under microbial-active and inactive conditions. Citrate adsorption isotherms for all soils were adequately described by the Freundlich equation with the R 2 value being over 0.90. The Cecil soil had the highest affinity for citrate adsorption among the soils with 99% adsorption observed throughout the citrate concentration range, which was due primarily to the abundant Al and Fe oxides. Citrate sorption to the mineral phase significantly reduced its biodegradation by 56%, 65% and 99% for the Creedmoor, Norfolk and Cecil soils, respectively. The results suggest the efficiency of rhizosphere processes for Al detoxification by root-secreted citrate would be significantly reduced in acid soil with abundant Al and Fe oxides.}, number={12}, journal={APPLIED GEOCHEMISTRY}, author={Hashimoto, Yohey}, year={2007}, month={Dec}, pages={2861–2871} }