colorimetric molybdenum blue
method [18]. Briefly, 0.3 g samples of rice leaves were ashed in porcelain crucibles for 3 h
at 550°C, the ash was dissolved in 1.3% hydrogen fluoride, then the Si concentrations in
the solutions were measured by the colorimetric molybdenum blue method at 811 nm with
a spectrophotometer (PGENERAL TU-1901 UV-VIS, Beijing, China). A control (no
sample) was added to eliminate porcelain crucible errors.