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This article in AJ

  1. Vol. 104 No. 6, p. 1604-1611
     
    Received: June 11, 2012
    Published: September 13, 2012


    * Corresponding author(s): btubana@agcenter.lsu.edu
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doi:10.2134/agronj2012.0214

In-Season Canopy Reflectance-Based Estimation of Rice Yield Response to Nitrogen

  1. B. S. Tubaña *a,
  2. D. L. Harrellb,
  3. T. Walkerc,
  4. J. Teboha,
  5. J. Loftona and
  6. Y. Kankea
  1. a School of Plant, Environmental and Soil Sci., Louisiana State Univ. Agricultural Center, 104 Sturgis Hall, Baton Rouge, LA 70803
    b Louisiana State Univ. Agricultural Center-Rice Research Station, 1373 Caffey Road, Rayne, LA 70578
    c Mississippi State Univ. Delta Res. and Ext. Center. Published with the approval of the Director of the Louisiana Agricultural Experiment Station as publication number 2012-306-7579

Abstract

A sensor-based approach to derive N recommendation based on crop needs and seasonal variation in yield potential and plant-available soil N requires an estimate of in-season rice (Oryza sativa L.) response to applied N. The objectives of this study were to: (i) determine if normalized difference vegetation index (NDVI) readings can be used to predict rice grain yield response to applied N and (ii) establish the relationship between NDVI-estimated response index (RI-NDVI) and measured response index at harvest (RI-YIELD). Sensor and yield data were collected from multiple N-rate trials from different locations in Louisiana and Mississippi from 2008 to 2010. The NDVI readings were collected using a ground-based active sensor at panicle initiation (PI), one (PI + 1 wk) and 2 wk (PI + 2 wk) after PI. Two sets of RI values were computed: (i) the ratio of the highest yielding N-fertilized plot to the check plot and (ii) ratio of N fertilized plots to the check plot. Across sampling dates, significant linear relationships were obtained between RI-NDVI and RI-YIELD (P < 0.01). The highest coefficient of determination value (r2) obtained between estimated and measured RIs was obtained at PI + 1 wk (r2 = 0.63). The quality of the models was improved when RI values were computed by comparing all variable rate N-fertilized plots to the check plot. Our results showed that RI-YIELD can be predicted using RI-NDVI measured within a 3-wk period starting at PI which is in synchrony with the schedule of topdress N application in mid-southern United States rice production systems.

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Copyright © 2012. Copyright © 2012 by the American Society of Agronomy, Inc.