Indonesian Journal of Agricultural Science Vol. 18 No. 2 December 2017: 69–76 DOI: http//dx.doi.org/10.21082/ijas.v.18.n2.2017.p.69–76 RELEASE OF SILICON FROM SILICATE MATERIALS AND ITS UPTAKE BY RICE PLANT Pelepasan Silika dari Bahan Silikat dan Penyerapannya oleh Tanaman Padi Linca Anggria a* , Husnain a , Kuniaki Sato b and Tsugiyuki Masunaga b a Indonesian Soil Research Institute Jalan Tentara Pelajar No.12 Bogor 16124, West Java, Indonesia Phone: +62 251 8336757, Fax: +62 251 8321608, 8322933 b Faculty of Life and Environmental Science, Shimane University, Japan *Corresponding author: anggria_linca@yahoo.com Submitted 09 October 2017; Revised 02 November 2017; Accepted 20 Desember 2017 ABSTRACT Plants absorb silicon (Si) from soil solution in the form of monosilicic acid, also called orthosilicic acid (H 4 SiO 4 ). Application of organic and inorganic materials containing readily soluble Si can increase Si supply in the soil and its uptake by plant. The study aimed to evaluate the release of Si from organic and inorganic material sources and its uptake by rice plant. The released phosphorus (P) from those materials was also evaluated. The inorganic materials evaluated included fy ash, steel slag, silica gel and Japanese silica gel (JSG), while the organic materials consisted of rice husk ash (RHA), rice husk burnt (RHB), media of mushroom (MM), cacao shell biochar (cacao SB) and rice straw compost (RSC). The dynamics of Si and P were observed by periodical samplings at 7, 17, 24 and 34 days after transplanting (DAT). Tiller number and plant height were measured at 16, 21 and 36 DAT. The results showed that Si concentration in solution derived from inorganic material was highest for JSG followed by silica gel (1.107 and 0.806 mmol L -1 , respectively). The release of Si from organic material was higher for RHB and RHA (0.618 and 0.539 mmol L -1 , respectively). Cacao SB, silica gel, JSG and RHB signifcantly increased plant height at 36 DAT. Meanwhile, Si materials did not signifcantly afect the tiller number. Of the materials used, steel slag and JSG signifcantly afected Si uptake by rice plant. [Keywords: rice, silicate materials, silicon, silicon uptake] ABSTRAK Tanaman menyerap silikon dari larutan tanah dalam bentuk asam monosilikat, yang juga disebut asam ortosilikat (H 4 SiO4). Penggunaan bahan organik dan anorganik yang mengandung Si yang cepat tersedia bagi tanaman dapat meningkatkan ketersediaan Si dalam tanah dan penyerapannya oleh tanaman. Penelitian ini bertujuan untuk mengevaluasi pelepasan Si dari bahan organik dan anorganik dan penyerapannya oleh tanaman padi. Pelepasan fosfor (P) dari bahan-bahan sumber Si tersebut juga dievaluasi. Bahan anorganik yang diteliti meliputi abu terbang (fy ash), terak baja, silika gel, dan silika gel Jepang, sedangkan untuk bahan organik terdiri atas abu sekam padi (RHA), sekam padi bakar (RHB), media jamur (MM), biochar kulit buah kakao (cacao SB), dan kompos jerami padi (RSC). Pengamatan dinamika Si dan P dilakukan secara berkala pada 7, 17, 24, dan 34 hari setelah tanam (HST), sementara jumlah anakan dan tinggi tanaman padi diamati pada 16, 21, dan 36 HST. Hasil penelitian menunjukkan bahwa konsentrasi Si dalam larutan yang berasal dari bahan anorganik paling tinggi untuk JSG dan diikuti oleh silika gel, masing-masing 1,107 dan 0,806 mmol L -1 . Pelepasan Si dari bahan organik tertinggi terdapat pada RHB dan RHA (0.618 dan 0.539 mmol L -1 ). Biochar kulit buah kakao, silika gel, JSG, dan RHB nyata meningkatkan tinggi tanaman padi pada 36 HST. Sumber Si tidak memengaruhi jumlah anakan tanaman. Dari bahan yang digunakan, terak baja dan silika gel Jepang (JSG) nyata memengaruhi serapan Si oleh tanaman padi [Kata kunci: bahan silikat, padi, penyerapan silika, silika] INTRODUCTION Silicon (Si) is the second most common element of the earth’s crust (Wedepohl 1995). Silica minerals undergo chemical and physical weathering which release Si into soil solution, followed by combination with other elements to form clay minerals or release toward the streams and oceans or to be absorbed by vegetation (Guntzer et al. 2012). The form of Si absorbed by plant root is silicic acid (Datnof et al. 2001). According to Matichenkov and Bocharnikova (2001), monosilicic acid, polysilicic acid, organo-silicon compound and complex compounds with organic and inorganic substances are the mobile forms of Si. By replacing phosphorus (P) from calcium (Ca), aluminum (Al) and magnesium (Mg) phosphates, monosilicic acid can control the mobility of phosphates and transform plant- unavailable P into plant-available P (Matichenkov and Ammosova 1996). Silica as a benefcial element for plant may reduce biotic and abiotic stresses. Si has been recognized for reducing rice blast caused by fungus Magnaporthe grisea (Winslow et al. 1997; Meena et al. 2014) and enhancing wheat resistance to freezing stress (Liang et al. 2008)