Which of the following is most important in inhibiting the digestibility of paddy straw?

Silica is most important in inhibiting the digestibility of paddy straw.
The presence of silica in the outer layer of rice straw reduces enzymatic hydrolysis and ethanol production yield.
Silica removal from rice straw was investigated through various alkali treatments. The results showed that sodium carbonate could effectively remove silica from the straw (> 91%).