Fig. 7.

Estimation of the number of wheat seedlings with different leaf ages and densities using the coverage degree. The datasets are these images for model training (720 observations), and each treatment has 60 data. The densities of images from the first line to the fourthly are 75 × 10⁴ plants ha⁻¹, 150 × 10⁴ plants ha⁻¹, 225 × 10⁴ plants ha⁻¹, 300 × 10⁴ plants ha⁻¹