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    • Keywords


      Leaf area index; vegetation index.

    • Abstract


      The time of forcing of spatial LAI to crop models at single or multiple stages is important to simulate crop biomass and yield in varying agro-climatic conditions and scales. The high temporal resolution (5-day) by Advanced Wide Field Sensor (AWiFS) on-board Resourcesat-1 Satellite IRS-P6 with 56 m spatial resolution and large swath (740 km) has substantially increased the availability of regional clear sky optical remote sensing data. The present study aimed at developing empirical vegetation index VI-LAI models for wheat using AWiFS optical data in four bands and in-situ measurements sampled over five different agro-climatic regions (ACRs) during 2005–2006 followed by validation during 2006–2007. While nonlinear relations exist for all the three normalized indices such as normalized difference vegetation index (NDVI), normalized difference water index (NDWI) and Green NDVI, linear relation was the best fit for ratio vegetation index (RVI). Both NDVI and RVI models generally showed better correlation ranges (0.65–0.84 for NDVI and 0.37–0.76 for RVI) than other indices. The common NDVI-LAI model was found to produce lower root mean square errors (RMSE) between 0.5 and 1.1 from pooled model than those between 0.5 and 1.32 from regional models. The rate of substantial increase in errors from NDVILAI model (RMSE of modelled LAI: 0.85 to 1.28) as compared to RVI-LAI model (RMSE of modeled LAI: 1.12 to 1.17) at LAI greater than 3, than below 3 revealed the early saturation of NDVI than RVI. It is therefore recommended that LAI estimates can be used to force crop simulation model up to early vegetative stage based on NDVI and maximum vegetative to reproductive stages based on RVI.

    • Author Affiliations


      Sasmita Chaurasia1 R Nigam1 B K Bhattacharya1 V N Sridhar1 K Mallick1 S P Vyas1 N K Patel1 J Mukherjee2 Chander Shekhar3 Dhiraj Kumar4 K R P Singh5 G D Bairagi6 N L Purohit7 J S Parihar1

      1. Earth, Ocean, Atmosphere, Planetary Sciences and Applications Area, Space Applications Centre (ISRO), Ahmedabad 380 015, India.
      2. Department of Agricultural Meteorology, Punjab Agricultural University, Ludhiana, India.
      3. CCS Haryana Agricultural University, Hisar, India.
      4. UP Remote Sensing Applications Centre, Lucknow, India.
      5. Bihar Remote Sensing Applications Centre, Patna, India.
      6. M.P. State Remote Sensing Applications Centre, Bhopal, India.
      7. Rajasthan State Remote Sensing Applications Centre, Jodhpur, India.
    • Dates

  • Journal of Earth System Science | News

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      Posted on July 25, 2019

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