Silicon-mediated sodium exclusion and biomass enhancement in rice under salinity stress

Abstract

Soil salinity is a major constraint to rice productivity in coastal regions, while silicon (Si) is recognized as a beneficial element in stress mitigation. However, the mechanisms underlying its interaction with salinity and rice genotypes remain insufficiently understood. A pot experiment was conducted during early-monsoon season, 2023 at Patuakhali Science and Technology University, Bangladesh, to investigate the role of Si amendment in reducing sodium (Na) uptake, and enhancing biomass production in contrasting rice genotypes. The treatments comprised two salinity levels (0 and 6 dS m^− 1), two rice genotypes (BRRI dhan48 and Malachina), and two Si rates (0 and 100 mg Si kg^− 1 soil, applied as calcium silicate) arranged in a factorial design. Salinity significantly reduced plant height, tiller number, leaf area, and root and shoot dry weight, whereas Si application improved these parameters by 4.0%, 10.7%, 24.8%, 16.6% and 20.0%, respectively. Silicon supplementation increased root Si content by 44.1% under non-saline conditions and 85.7% under saline conditions; while shoot Si content increased by 26.9% and 45.9%, respectively compared with Si control. Furthermore, under saline conditions, Si application reduced shoot Na content by 11%. The traditional variety Malachina exhibited greater biomass production and higher Si uptake than BRRI dhan48, indicating genotypic differences in Si-mediated stress tolerance. Overall, the findings demonstrate that Si amendment alleviates salt stress in rice by enhancing Si uptake, restricting Na translocation, and promoting chlorophyll content and biomass yield. These results suggest that integrating Si fertilization into rice production systems could improve the resilience and productivity of coastal agriculture.