Physiological Performance and Growth Responses of Ratoon Sugarcane to Hydrogel, Nano-Silica Particles, and K-Humate Applications

Abstract

Ratoon sugarcane cultivation systems experience declining productivity due to soil degradation, which adversely affects plant physiological capacity. This study evaluated physiological and growth responses of the Bulu Lawang ratoon sugarcane variety to hydrogel, silica nanoparticles (SiNPs), and K-humate, applied individually and in combination to improve soil physical, chemical, and biological properties. A field experiment used a randomized complete block design with seven treatments under uniform NPKS fertilization. Parameters observed included nitrogen metabolism, chlorophyll content, gas exchange, photosynthetic rate, vegetative growth, and biomass. The combination of SiNPs and K-humate, with or without hydrogel, produced the most favorable responses, increasing nitrate reductase activity by 147%, total chlorophyll by 75%, stomatal conductance by 194%, and photosynthetic rate by 89% relative to the control, with corresponding gains in leaf area, root area, plant population, and dry biomass. Hydrogel provided no additional benefit beyond that of SiNPs and K-humate under the high-rainfall conditions of this study. Correlation analysis showed strong positive relationships between nitrogen metabolism and chlorophyll synthesis, photosynthetic rate and leaf and root area, and photosynthesis and biomass, indicating an integrated physiological response. These findings indicate that SiNPs and K-humate, rather than the hydrogel, primarily drive improvements in ratoon sugarcane productivity on degraded soils.