Effect of Combined Application of Foliar Sprays of Orthosilicic Acid (OSA) with Basal NPK Fertilizer on Growth and Yield of Rice (Oryza sativa L.)

Benefits of silicon to plant growth and yield in higher plants has been explored recently. This study was conducted to assess effects of application of foliar application of stabilized Orthosilicic Acid (OSA) with NPK fertilizer on growth and yield of rice. The study was conducted in Ntende site at Rwagitima marshland, Gatsibo district in the Eastern province of Rwanda. The field experiment was laid in randomized complete block design with three replications across two cropping seasons in 2019 and 2020. Two recommended doses of fertilizer (RDF); 100 % RDF (200 kgha− 1 NPK and 100 kgha− 1 Urea) and 75 % RDF (150 kgha− 1 NPK and 75 kgha− 1 Urea) were used in combination with different doses of stabilized orthosilicic acid (OSA), a commercial formulation is named as Silixol OSA (referred as OSA in the text). The Si fertilizer was applied in at panicle initiation and grain filling stages, at three different doses (2 ml/l, 3ml/l and 4 ml/l). Combined application of Silixol OSA with RDF produced better growth attributes (plant height, number of tillers, root length, flag leaf length and width) compared to that of RDF only. Similarly, OSA application showed higher yield components, number of panicles, panicle weight, grain weight per panicle and 1000-grain weight. Highest yield of 5.81 t/ha which equates to 24 % increase was obtained when 100 % RDF + 4ml/l OSA was applied. Interestingly, when OSA was used at 4ml/l dose, with 75 % RDF, it attributed to significant increase in yield. Rice fertilization with OSA helps to stimulate plant growth, yield attributes and yield. Therefore, potential of Si could further be explored among rice farmers in Rwanda. Further saving of 25 % of fertilizer dose would be a good economic benefit to farmers as well as government of Rwanda. Lesser use of fertilizers would also reduce the risk of degradation of environment following the application of OSA fertilizer.