Comparative effectiveness of soil and foliar application of different silicon sources on wheat productivity in coastal soils of the Ganges delta

Silicon (Si) has emerged as a beneficial nutrient element for increasing crop resilience under various stresses; however, limited information is available regarding the comparative performance of different application methods and sources for wheat production in coastal areas of the Ganges delta. A field experiment was conducted during two consecutive winter seasons of 2024–25 and 2025–26 in Patuakhali district of Bangladesh, to examine the effects of different Si sources and application methods on growth, yield, Si uptake and economic performance of wheat in coastal soil. The experiment was laid out in a randomized complete block design with three replications comprising seven treatments: control, soil application of calcium (Ca) silicate, sodium (Na) meta-silicate, and Si dioxide (80 kg Si ha −1 ), and foliar spraying in the morning four times of the same sources as 0.3% Si solution (total 30 kg Si ha −1 ). Data were statistically analysed following two-way ANOVA model where year and Si treatments were the factors. Si supplementation significantly increased plant height, tillers m −2 , spike length, grains spike −1 , 1000 grain weight, grain yield, straw yield, straw Si content and straw Si uptake. Among treatments, foliar Si dioxide provided the highest grain yield (4.47 t ha −1 ), representing a 21.8% increase over control (3.67 t ha −1 ) which was statistically similar with foliar Na meta-silicate (4.21 t ha −1 ) and soil applied Si dioxide (4.17 t ha −1 ). Foliar Si dioxide also resulted in the highest grains spike −1 (31.9) and straw yield (5.99 t ha −1 ). The Si uptake efficiency and economic efficiency (MBCR) of foliar applied Si was much better than the soil application, and among the sources Si dioxide was the greatest. Overall, the results endorse that Si dioxide both in foliar spray or soil application was the best-performing treatment under tested single-site conditions and requires multi-location validation.