Spectral estimation of the aboveground biomass of cotton under water–nitrogen coupling conditions

Table 3 Cotton AGB Estimation model based on machine learning

Spectral variable	Modeling approach	Growth stage	Training set			Validation set
Spectral variable	Modeling approach	Growth stage	R²	RMSE (g)	RPD	R²	RMSE (g)	RPD
characteristic wavelengths	SVM	bud stage	0.58	9.82	0.47	0.57	1.06	4.73
		flowering stage	0.62	9.68	14.11	0.60	3.48	2.15
		boll stage	0.76	0.35	17.59	0.73	0.74	10.14
	RT	bud stage	0.79	0.24	16.18	0.64	0.10	35.49
		flowering stage	0.71	1.84	4.10	0.73	2.27	3.47
		boll stage	0.48	12.54	0.58	0.56	2.58	3.36
	CNN	bud stage	0.70	0.42	4.50	0.55	0.46	4.62
		flowering stage	0.57	2.31	2.38	0.54	1.04	5.43
		boll stage	0.59	2.36	2.71	0.58	3.99	1.69

ISSN: 1746-4811