Time-series of NDVI and CI_{red edge} was obtained through ground-based spectrometers and smoothed by double logistic regression function.

The positions of the maximum, zero-crossing and minimum points in the first derivative of the smoothed CI_{red edge} temporal profiles can be used to estimate the dates of jointing, middle booting and dough grain, respectively.

The positions of the maximum, zero-crossing and minimum points in the first derivative of the smoothed NDVI temporal profiles can be used to estimate the dates of active tillering, middle heading and maturity, respectively.

Between the NDVIs from passive and active sensors, NDVI_GS yielded better performance than NDVI_ASD for estimating thephenological dates.

Rice cultivar and N rate exhibited more impact on the estimation accuracy than growing season and planting density.