Silicon-induced leaf structural reinforcement modulates growth, foliar disease and yield performance of rice under nutrient-limited conditions

Nutrient imbalance can compromise rice (Oryza sativa L.) cultivation, hindering the potential of rice plants to produce optimum grain yield. In this study, Si was added as a supplementary fertilizer to reinforce leaf anatomical structure, modulating growth performance, foliar disease resistance, and yield under nutrient-limited conditions. Four fertilization treatments were evaluated using a randomized complete block design, including the use of conventional NPK with and without Si addition. Its effect on leaf structural reinforcement and nutrient accumulation was assessed. Growth parameters, foliar disease severity, incidence, the area under the disease progress curve (AUDPC), and yield components were evaluated across all phenological stages. The results showed that Si accumulation in the leaf, stress-induced or fertilized, significantly affected Mg (194.8 mg kg-1 DW) and Zn (82.9 mg kg-1) without compromising P and K uptake. Structural reinforcements of the leaf evaluated included increased thickness of the cuticle (18.3 μm) and mesophyll (256.2 μm), higher stomatal density (473.9 stomata mm-2), and higher chlorophyll content (15.4 SPAD index). Si modulated vegetative growth and biomass during grain filling. Furthermore, Si accumulation reduced AUDPC values for bacterial red stripe, leaf blight, and narrow brown spot from 771.1 to 159.1 %-days, 119.9 to 9.9 %-days, and 786.1 to 452.1 %-days, respectively, demonstrating high resistance toward foliar diseases. Grain yield at 14% moisture content was similar among treatments (6.15-6.24 t ha-1). Si fertilization increased physiological efficiency, strengthened leaf structural defenses, and reduced disease-induced yield losses. It may be used to compensate for or substitute nutrient deficiencies, potentially reducing the quantity of conventional fertilizer required in agricultural practices.