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Title: POTENTIAL USE OF NITROGEN REFLECTANCE INDEX TO ESTIMATE PLANT PARAMETERS AND YIELD OF MAIZE

Author
item Diker, Kenan
item Bausch, Walter

Submitted to: Biosystems Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2003
Publication Date: 6/20/2003
Citation: DIKER, K., BAUSCH, W.C. POTENTIAL USE OF NITROGEN REFLECTANCE INDEX TO ESTIMATE PLANT PARAMETERS AND YIELD OF MAIZE. BIOSYSTEMS ENGINEERING. 2003.

Interpretive Summary: In-season plant stress conditions can cause severe yield reduction. So, producers need a timely determination of any plant stress conditions occurring during the growing season. Once the plant stress is determined in any particular area in the field then, producers can apply the necessary management operations in that particular area to correct the problem and they can produce the optimal yield. This study was conducted to evaluate the Nitrogen Reflectance Index (NRI) for its performance in predicting plant variables Leaf Area Index (LAI) and dry matter as plant stress indicators, as well as yield of corn with two different canopy structures in comparison with commonly used Normalized Difference Vegetation Index (NDVI) and Modified Soil Adjusted vegetation Index (MSAVI). It was determined that the NRI was related well with the plant variables at all the growth stages of corn, except at early stage. Data showed also that the NRI was superior to NDVI and MSAVI for predicting the final crop yield. Mapping spatial distribution of the plant variables estimated by the NRI would be a reliable way to determine the stress areas and make necessary amendments to those areas for being able achieve the optimal yield.

Technical Abstract: Estimating the spatial variability of various plant parameters during the growing season can assist in timely correction of stress conditions within a field. This research illustrates that the nitrogen reflectance index (NRI) developed to estimate plant nitrogen status can be used to estimate plant parameters and yield potential. The study was conducted on two experimental maize sites. Selected maize hybrids were 'Pioneer 3790', which was a planophile canopy architecture and 'NC+ 1598' with an erectophile canopy architecture. The first site consisted of six non-replicated fertiliser plots. Data from these plots were used to develop the relationships between reflectance data and the plant parameters. The second site contained four plots with various nitrogen (N) and water treatments on which the developed relationships were verified. Leaf area, biomass, and plant reflectance data were collected almost weekly from both sites during the 1996 growing season. Measured and estimated yield, leaf area index (LAI) and dry matter were mapped in ArcVIEW geographical information system. Results showed that the NRI was a comparable estimator of potential yield to the normalised difference vegetation index or to the modified soil adjusted vegetation index. For the leaf area index (LAI) and biomass, all vegetation indices produced similar coefficients of determination. Results showed that the NRI could be used to estimate the within-field variation of yield potential and plant parameters.