Differences in plant canopy bi-directional reflectance factors among rice varieties

We statistically discuss the possible ways to classify rice varieties using canopy bi-directional reflectance factor (BRF) data. Fourteen varieties of rice (Oryza sativa L.) were grown in an experimental paddy field where environmental conditions such as soil, nutrients, water supply, and local climate were homogeneous. Spectral reflectance of each of the rice varieties was measured at nadir and at off-nadir angles of 45°, 30°, 15°, −15°, −30°, and −45° on both the principal and perpendicular planes at intervals of 1 nm from 400 to 850 nm. The reflectances in green (550–560 nm), red (675–685 nm), and near infrared (745–749 nm) bands at every measuring angle were computed for each rice variety. As a result of unpaired Student t-tests, the number of pairs of rice varieties that can be statistically distinguished using BRF data was larger than the number that can be distinguished using just the spectral reflectance data at the nadir angle. The difference in BRF among rice varieties was statistically significant.