Table 1. List of the measured traits with their abbreviations.

Trait	Abbreviation
Longest leaf length	LLGTH
Number of tillers	NBT
Shoot biomass	SB
Deepest point reached by the roots in position in the plates	DEPTH
Maximum root length	LENGTH
Angle to the vertical of the root cone	ANGLE
Number of roots reaching 30 cm depth	NBR_30
Root dry mass in the 00-20 cm layer	RB0020
Root dry mass in the 20-30 cm layer	RB2030
Root dry mass below 30 cm	RBB30
Deep root biomass	DRB
Deep root proportion	DRP
Root biomass	RB
Plant biomass	PB
Root to shoot ratio	R_S