Context : The abundance ratio N/O is a useful tool to study the interplay of galactic processes , e.g .
star formation efficiency , time-scale of infall and outflow loading factor

Aims : We aim to trace \log ( N/O ) versus [ Fe/H ] in the Milky Way and to compare it with a set of chemical evolution models to understand the role of infall , outflow and star formation efficiency in the building-up of the Galactic disc .

Methods : We use the abundances from idr2-3 , idr4 , idr5 data releases of the Gaia-ESO Survey both for Galactic field and open cluster stars .
We determine membership and average composition of open clusters and we separate thin and thick disc field stars .
We consider the effect of mixing in the abundance of N in giant stars .
We compute a grid of chemical evolution models , suited to reproduce the main features of our Galaxy , exploring the effects of the star formation efficiency , the infall time-scale and the differential outflow .

Results : With our samples , we map the metallicity range -0.6 \leq [ Fe/H ] \leq 0.3 with a corresponding -1.2 \leq \log N/O \leq -0.2 , where the secondary production of N dominates .
Thanks to the wide range of Galactocentric distances covered by our samples , we can distinguish the behaviour of \log ( N/O ) in different parts of the Galaxy .

Conclusions : Our spatially resolved results allow us to distinguish differences in the evolution of N/O with Galactocentric radius .
Comparing the data with our models , we can characterise the radial regions of our Galaxy .
A shorter infall time-scale is needed in the inner regions , while the outer regions need a longer infall time-scale , coupled with a higher star formation efficiency .
We compare our results with nebular abundances obtained in MaNGA galaxies , finding in our Galaxy a much wider range of \log ( N/O ) than in integrated observations of external galaxies of similar stellar mass , but similar to the ranges found in studies of individual H ii regions .