Table 6.

Regression coefficients of the relationships between the RGB-indices, measured at ground and aerial levels, with grain yield. These indices are defined at section Material and Methods. Level of significance (p-value): *, p < 0.05; **, p < 0.01; ***, p < 0.001. Treatments: CA, conservation agriculture; CP, conventional agriculture; LD, low density; HD, high density.

		Intensity	Hue	Saturation	Lightness	a*	b*	u*	v*	GA	GGA
Ground measurements	Tillage
	CA	−0.065	0.484***	−0.317*	−0.021	−0.509*	−0.226	−0.544***	−0.137	0.487***	0.507***
	CP	0.503***	0.741***	−0.478***	0.568***	−0.742***	−0.206	−0.717***	0.157	0.777***	0.783***
	Planting density
	LD	0.342*	0.597***	−0.483***	0.366*	−0.633***	−0.350*	−0.623***	−0.152	0.660***	0.662***
	HD	0.361*	0.754***	−0.509***	0.410**	−0.785***	−0.326*	−0.771***	−0.100	0.767***	0.767***
	Combinations
	CA * LD	−0.054	0.422*	−0.386	−0.032	−0.498*	−0.310	−0.539**	−0.213	0.511*	0.513*
	CA * HD	−0.054	0.580**	−0.247	0.020	−0.570**	−0.138	−0.585**	−0.052	0.493*	0.528**
	CP * LD	0.419*	0.622	−0.304	0.456*	−0.596**	−0.032	−0.567**	0.218	0.627**	0.636***
	CP * HD	0.565**	0.827***	−0.594**	0.671***	−0.850***	−0.318	0.830***	0.176	0.894***	0.898***
Aerial mesurements	Tillage
	CA	−0.393**	0.548***	−0.149	−0.363*	−0.567***	−0.265	−0.554*	−0.145	0.562***	0.561***
	CP	−0.776***	0.754***	−0.719***	−0.777***	−0.796***	−0.818***	−0.812***	−0.794***	0.784***	0.798***
	Planting density
	LD	−0.555***	0.614***	−0.495***	−0.565***	−0.651***	−0.606***	−0.658***	−0.617***	0.653***	0.664***
	HD	−0.627***	0.684***	−0.440**	−0.631***	−0.739***	−0.667***	−0.751***	−0.697***	0.776***	0.786***
	Combinations
	CA * LD	−0.468*	0.582**	−0.292	−0.444*	−0.600**	−0.395	−0.594**	−0.296	0.578**	0.572**
	CA * HD	−0.360	0.519**	−0.105	−0.331	−0.544**	−0.262	−0.533**	−0.116	0.545**	0.557**
	CP * LD	−0.606**	0.577**	−0.649***	−0.610**	−0.654***	−0.694***	−0.674***	−0.662***	−0.662**	0.633***
	CP * HD	−0.907***	0.881***	−0.793***	−0.906***	−0.900***	−0.920***	−0.913***	−0.905***	0.916***	0.920***