Arid Zone Research ›› 2024, Vol. 41 ›› Issue (6): 1069-1078.doi: 10.13866/j.azr.2024.06.15

• Agricultural Ecology • Previous Articles     Next Articles

Estimation of nitrogen contentration in winter wheat leaves based on hyperspectral images of UAV

SUN Fafu1,2,3(), LAI Ning1,2, GENG Qinglong1,2, LI Yongfu1,2, LV Caixia1,2, XIN Huinan1,2, LI Na1,2, CHEN Shuhuang1,2()   

  1. 1. Institute of Soil, Fertilizer and Water Saving Agriculture Xinjiang Academy of Agricultural Sciences, Urumqi 830091, Xinjiang, China
    2. Agricultural Remote Sensing Center, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, Xinjiang, China
    3. College of Resources and Environmental Sciences, Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China
  • Received:2023-12-01 Revised:2024-04-20 Online:2024-06-15 Published:2024-07-03

Abstract:

Established leaf nitrogen concentration (LNC) is the response of crop photosynthesis, an important index of nutrition and growth. To accurately and efficiently estimate different growth period of winter wheat LNC, with the new winter 22 as the research object, using the (UAVs) Pika L hyperspectral cameras for four key growth period of winter wheat canopy reflectance data. The LNC-sensitive spectral index was screened based on the band optimization algorithm and correlation analysis. Stepwise regression, multiple linear regression, and partial least squares regression were combined to establish the estimation model of winter wheat LNC in each key growth stage, which was compared with the single variable estimation model. The results showed that (1) the correlation between the combined spectral index screened using the band optimization algorithm and LNC was stronger than that obtained using the traditional vegetation index and was extremely significant; (2) the combined spectral index in the single variable LNC estimation model allowed to obtain a more accurate model compared with the traditional vegetation index, including Yang flowering DSI(R940, R968) estimate model is set up, best R2 of 0.789. The multi-variable estimation models were more accurate than the single variable estimation models and, among them, the LNC estimation model based on partial least squares regression was the best, and the fitting effect of the booting and flowering stages was better. This model had a coefficient of determination of 0.923 and root-mean-square errors of 0.082 and 0.084. The results of this study provide a theoretical basis and technical support to estimate the LNC of winter wheat and monitor its growth.

Key words: winter wheat, leaf nitrogen content (LNC), unmanned aerial vehicle (UAV), hyperspectral, partial leastsquares regression, combination of spectral index