Nitrogen assessment of lowland rice (Oryza sativa L.) at different growth stages using low altitude remotes sensing
2016
Cuevas, C.M.C.
Rapid and non destructive assessment of the nitrogen status can be achieved using low altitude remote sensing technology. This study demonstrated the use of Unmanned Aerial Vehicle (UAV) with on-board NDVI camera in assessing nitrogen status of irrigated lowland rice. A nutrient omission plot experiment for lowland rice was conducted during the dry season (January 2016 to May 2016) in a 1, 500 sq m experimental field. A series of aerial images of rice field were captured at different growth stages. These images were stitched and orthorectified to produce a geo-referenced mosaic map of the rice field. Quantum GIS was used to convert the mosaic map into normalized difference vegetation index (NDVI) map. Ground-based measurements of rice leaf chlorophyll content were also performed using SPAD 502 leaf chlorophyll meter. From tillering to grain filling stage, the observed differences in SPAD and NDVI values between 0.30-30 and 90-30-30 kg/ha NPK ranged from 9% to 18% and 9% to 30%, respectively while 20% to 40% and 54% to 68% respectively, between 0-0-0 and 90-30-30 kg/ha NPK. The results suggest that AUV system can detect nitrogen deficient rice plots. Strong correlation between SPAD and NDVI values (p0.001 was observed during the flowering stage (r
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