Sources and Application Methods of Silicon for Rice in Acid Soil

Rice (Oryza sativa L.) is a key food grain crop in acid soil regions of the world. An economical and efficient nutrient application method should be developed for crops in acidic soil region. Use of Si as a source of beneficial nutrient is well known. Therefore, a pot experiment was planned with rice variety CAU-R1 to find out the effective combination of application method and source of Si. Three sources of Si viz. silicic acid (C1), calcium silicate (C2), and sodium meta silicate (C3), and five different application methods: (1) M1, seedling root-dipping (SRD) in soil: water slurry (applied @ 225 mg kg⁻¹ soil as silicic acid, calcium silicate and sodium meta silicate), (2) M2, foliar spray (1% Si) at the vegetative stage (FSV), (3) M3, foliar spray (1% Si) at the reproductive stage (FSR), (4) M4, foliar spray vegetative + foliar spray reproductive, and (5) M5, seedling root dip + foliar spray reproductive. Plant growth parameters, soil nutrient status and plant nutrient uptake were determined at 45 days after transplanting and harvesting stage. Results indicated that silicic acid as seedling root dip method with 225 mg Si kg⁻¹ soil and sodium meta silicate foliar spray vegetative stage and reproductive stage method with 1% Si was found to be the best performing. This study also highlighted that choice of silicon source and application method may lead to decrease the cost of production for transplanted rice cultivation.