Table III.

Phenotypic and genotypic correlations between agronomic and physiological traits

Trait	N+					N−
	GY	KN	TKW	GNY	GME	GY	KN	TKW	GNY	GME
Leaf NO3− content	0.33a	0.17	0.19b	0.24c	0.19b	0.26c	0.18b	0.25c	0.34a	0.09
	(0.54)	(0.23)	(0.26)	(0.82)d	(0.30)	(0.44)	(0.29)	(0.29)	(1.00)d	(0.14)
Leaf NR activity	−0.19a	−0.02	−0.25b	0.01	−0.17	−0.22b	−0.17	−0.12	−0.04	−0.02
	(−0.28)	(−0.03)	(−0.30)	(0.03)	(−0.20)	(−0.32)	(−0.25)	(−0.15)	(−0.10)	(−0.10)
Leaf GS activity	0.15	0.07	0.15	0.28a	0.08	0.25c	0.21b	0.13	0.09	0.28b
	(0.24)	(0.12)	(0.19)	(0.93)d	(0.13)	(0.41)	(0.32)	(0.16)	(0.26)	(0.43)

N⁺ corresponds to plants grown in the field under high nitrogen input (N⁺ = 175 kg N/ha) and N⁻ to plants grown in the field with no nitrogen fertilization (soil N content = 60 kg N/ha). The physiological traits measured in young vegetative plants grown under greenhouse-controlled conditions are: Leaf NO₃⁻ content (mg dry wt⁻¹), leaf NR activity (μmol h⁻¹ mg⁻¹ protein), and leaf GS activity (nmol mn⁻¹ mg⁻¹ protein). The agronomic characters are GY (10⁻¹ t ha⁻¹), KN, TKW (g), GNY (g), and GME (ratio grain yield/N uptake in aerial biomass). Results are the mean of a 2-year experiment except for NR activity.

^a  

^b  

^c Phenotypic correlations significant respectively at 0.001, 0.05, and 0.01 probability levels. Genotypic correlations are indicated below in parentheses. 

^d Poor estimation of genotypic correlation due to a large environmental effect.