Background and aims <p>Quantifying the dynamic relationship between soil labile silicon (LSi) pools and rice silicon (Si) upstake during growth is crucial for improving regional rice Si accumulation and increasing crop yields.</p> Methods <p>We analyzed various silicon pools in soil and Japonica rice samples from paddy fields at tillering, spike and maturity stages. Correlation analysis and regression models were employed to determine their relationships.</p> Results <p>As rice develops, the Si content in rice plants transitions from a strong positive correlation with soil dissolved Si at the tillering stage to a strong positive correlation with other LSi fractions (e.g., adsorbed Si, sodium acetate-extractable Si), which have higher storage. Increasing the supply of plant-available silicon (PASi) in the soils of the study area promoted overall Si accumulation in rice plants, with a stronger response observed for straw and husk (Spearman's r: 0.39–0.64, p &lt; 0.05). Especially, the growth rate of Si concentration in local japonica rice straw showed an increasing and then leveling off trend with the soil PASi content. Local data revealed that the growth rate of straw Si accumulation increases with soil PASi when the japonica rice straw Si content is below 42 g kg⁻¹. Comprehensive cross-regional involving different soil Si contents showed a quadratic relationship between soil PASi and rice straw Si, indicating the existence of an upper limit to rice Si accumulation.</p> Conclusions <p>The response of rice Si accumulation in relation to different LSi fractions is contingent upon changes in crop Si demand at various growth stages. In regard to the current low soil PASi in the study area, additional Si fertilizer can effectively promote Si utilization in Japonica rice, but it should be noted that there is a certain physiological upper limit for crop Si accumulation.&#xa0;</p>