Influence of Different Rice Growth Stages on NDVI in the Latter Half of Growth and Relative Evaluation of Rice Yield and Rice Protein Content by NDVI for Paddy Fields

Abstract

The target area of this research is one in which the irrigation starting date and planted rice varieties were determined for each paddy field using satellite data and paddy cultivation ledger data. Due to utilizing normalized difference vegetation index (NDVI) images for managing the cultivation of rice paddies, the relationship between NDVI obtained from Sentinel-2 satellite data on June 29 (before the heading stage date) or August 1 (after the heading stage date) in 2018 and the rice planting period (date of transplanting five days after the start of irrigation) for the paddy fields where Akitakomachi (early-maturing cultivar) or Koshihikari (medium-maturing cultivar) rice was transplanted. Field lot average values of the NDVI aggregated for each field were used for the analysis. In addition, relative evaluations were conducted of the rice yield and rice protein content for the paddy fields where Akitakomachi rice was transplanted from date No. 1 (April 6–8) to date No. 5 (April 26 to May 2) based on the analysis results. The relative evaluation of rice yield was performed using the field lot average NDVI on June 29, and the relative evaluation of the rice protein content was performed using the field lot average NDVI on August 1. Fields judged to have a high rice yield and high rice protein content in this evaluation are fields that should be considered for reducing the amount of additional fertilization and the timing of additional fertilization. Providing this information to farmers should be useful for their cultivation management in the next year.