The paper describes the possibility of using land spectrometry data and high-resolution satellite images of the PlanetScope grouping to assess weediness of cereal crops. The objects of monitoring were on the territory of the Krasnoyarsk Agricultural Research Institute of Federal Research Center “Krasnoyarsk Science Center of SB RAS” (Middle Siberia, Krasnoyarsk region). For interpretation satellite images, the NDVI (Normalized Difference Vegetation Index) vegetation index was used. Biological assessment of the degree of crops weediness was determined on a four-level scale.
As the result of monitoring wheat crops the influence of weed vegetation on the value of NDVI of agricultural crops was revealed. The average NDVI for wheat planting with a low degree of weediness is higher than the NDVI of wheat plantings with a high degree of weediness. As the result of the analysis of the spectra of cultural and weed vegetation on July 09, 2019, a difference in the value of the spectral brightness coefficient in the near-infrared region was noted, which is mainly connected with different structure of plants. For wheat planting with a strong degree of weediness (3 level) in the near-infrared region, the spectral brightness coefficient reaches 50%, while with a weak degree of weediness (1 level) below 40%. The NDVI analysis of wheat plantings with different levels of weediness during the whole vegetation period showed the same dynamics. However, for fields with a low degree of weediness, the NDVI value reaches 0.5 in the middle of the growing season, while for fields with a high degree of weediness, the NDVI value reaches only 0.35. According to the satellite data, spatial distribution maps of NDVI were constructed in different time of growing season (July 09, 2019 and August 02, 2019). The areas of wheat plantings with different degrees of weediness are reliably revealed on them.