. 2018 May 23;9:1000. doi: 10.3389/fmicb.2018.01000

Table 6.

Correlations of root length (RL), surface area (SA), projection area (PA), root volume (V), root diameter (AD), nodule number (NN), nodule weight (NdW), and nitrogen content of the shoot (NS) and root (NR) of soybean inoculated with Bradyrhizobium japonicum USDA110 in hydroponic culture with low nitrogen but high phosphorous and magnesium supplies (LNHP (N−300 μmol/L and P−250 μmol/L) and LNHMg (N−300 μmol/L and Mg−1,000 μmol/L).

Parameter	Treatments	RL	SA	PA	V	AD	NN	NdW	NS
SA	LNHP	0.04	1.00
	LNHMg	0.58^**
PA	LNHP	−0.62^**	0.55^**	1.00
	LNHMg	0.74^***	0.69^***
V	LNHP	0.21^*	0.74^***	0.19^*	1.00
	LNHMg	0.75^***	0.26^*	0.64^**
AD	LNHP	0.43^**	0.43^**	−0.18^*	0.82^***	1.00
	LNHMg	−0.37^**	−0.64^**	−0.42^**	0.24^*
NN	LNHP	−0.06	0.91^***	0.78^***	0.57^**	0.25^*	1.00
	LNHMg	0.07	0.17^*	0.59^**	0.20^*	0.03
NdW	LNHP	−0.07	−0.53	−0.26^*	−0.31^*	0.23^*	−0.42^**	1.00
	LNHMg	0.06	−0.39^**	−0.17^*	0.00	0.32^*	0.31^*
NS	LNHP	−0.20^*	−0.90^***	−0.58^**	−0.69^***	−0.49^**	−0.95^***	0.33^*	1.00
	LNHMg	0.34^**	−0.29^*	0.37^**	0.55^**	0.08	0.08	−0.15^*
NR	LNHP	0.46^**	−0.09	0.01	−0.47^**	−0.42^**	0.14^*	−0.12^*	−0.16^*
	LNHMg	−0.53^**	−0.14^*	0.08	−0.29^*	0.22^*	0.81^***	0.19^*	−0.17^*

Significance levels for positive correlations are

P < 0.05 (significant),

^**

P < 0.01 (highly significant), and

^***

P < 0.001 (extremely significant).