Root dry weight increased in a quadratic fashion with the advancement
of plant age from 19 to 120 days (Figure 2). Whereas, shoot dry weight
increased in a linear fashion during growth cycle of the rice plants. Rice
plant weight mainly consists of organic matter like protein and carbohydrate.
Carbohydrates are composed of cell wall substances such as cellulose
and reserved substances like starch. The protein metabolism dominates in
the vegetative growth stage and carbohydrate metabolism does in the reproductive
growth stage (Murayama, 1995). The portion of inorganic matters
in the weight of rice plant is generally small. However, rice straw generally
has high silicon content. In mature shoot of rice silicon content can be as
high as 10% (Murayama, 1995).