Synergistic effects of silicon-induced photosynthesis and fungal diversity on sugarcane yield

Silicon (Si) plays a significant role in crop growth and development, thus being important for crop yield and quality. Although there have been some studies on the effects of Si on sugarcane, these have focused mainly on barrel or newly planted sugarcane, and there are still few studies on the specific mechanism by which Si affects sugarcane growth. We compared different parameters of three sugarcane varieties, ‘LC05–136’, ‘YT93–159’, and ‘ROC22’, under Si-free (T1) and Si application rates of 200 kg (T2), 400 kg (T3), and 600 kg (T4) per hectare during a 2-year field experiment. The results showed that the optimal application of Si (T2) significantly increased sugarcane yield by 6.82–23.57% and sugar yield by 8.05–20.01%. T2 also consistently improved the sprouting rate (0.38–46.67%) and tillering rate (2.97–13.53%). Moreover, optimal application of Si affected the ultrastructure of sugarcane leaves, increasing the quantity of leaf siliceous cells, and the distribution of rhizosphere fungi. At the genus level, Si application significantly decreased the relative abundance of pathogenic genera ( Fusarium and Gibberella ) while increasing beneficial genera ( Serendipita and Cercospora ). However, excessive Si application (T4) may have detrimental effects, underscoring the need for balanced application. A multi-analysis showed that under the T2 treatment, the root system of sugarcane was improved; the rates of germination and growth were increased, and photosynthesis (photosynthetic enzymes and photosynthesis-related genes) was increased, leading to improvements in sugarcane yield and quality. The study highlights the role of Si in augmenting the photosynthetic capacity of sugarcane and enriching the beneficial fungal richness of sugarcane soil, contributing to more sustainable agricultural practices.