Among the inputs usually used in the sugarcane production the nitrogen (N) is the most significant. With the use of ground-based canopy sensors to obtain vegetation indexes (VI), it is possible to obtain recommendations of nutrient supply in rates that will vary depending on the crop variability. One of the common VI used for estimating N to be applied is the NDVI (normalized difference vegetation index). However, studies have demonstrated that  other VIs are capable to minimize the interference of climate, soil and plant stress that may bias the quantity of biomass accumulated by the crop, showing to be more reliable in estimating the N plant status. We are studying the interference of different soil water levels and time of the day for the VI readings in a controlled greenhouse environment and on field experiments exploring the interference of different surface background, nitrogen rates, soil water content and wet leaves condition. The readings have been obtained with a CropCircle sensor ACS-470 Multi-spectral (Holland Scientific Inc., Lincoln, NE, USA), calculating CI, GNDVI, NDRE, VI-Yara, MCARI/MTVI2 e MCARI/OSAVI, in comparison with NDVI.  Two portable chlorophyll meters SPAD-502 (Konica Minolta Sensing, Inc., Sakai, Osaka, Japan) and ClorofiLOG (Falker Automação Agrícola, Porto Alegre, Brazil) were also used. Up to now some relationships have been observed between the VIs towards the water stress and the plant biomass. The growing season is stepping up and measurements will continue until February 2012, with the final results.