To evaluate the effect of silica and phosphorous application on the growth and yield of a local rice variety, a field study was conducted in 1997 in Rice Research Institute of Iran (RRII). A split plot in a RCBD was adopted with four replications including different levels of silicate application (0, 400, 800 and 1600 kg/ha calcium silicate) as sub plots and rates of P2O5 application (0, 25, 50 and 100 kg/ha P2O5 as triple super phosphate) as main plot. Rice grain yield, silicon and phosphorous concentration in the shoot of rice plant, dry matter and total P as well as Si uptake in plant tops were determined at ripening stage. Results showed that effect of phosphorous on the grain yield, and effect of Si application on the dry matter, Si concentration and total uptake of Si and P were significant. Although among different rates of P2O5 and calcium silicate, application of 25 kg/ha P2O5 and 400 kg/ha calcium silicate showed higher dry matter and grain yield, but a combination of 25 kg/ha P2O5 with 800 kg/ha calcium silicate produced highest grain yield. This may indicate positive interaction of silica with phosphorous on the growth as well as rice grain yield.
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