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We have analysed the [OI]6300 A line in a sample of 131 young stars withdiscs in the Lupus, Chamaeleon and signa Orionis star forming regions, observedwith the X-shooter spectrograph at VLT. The stars have mass accretion ratesspanning from 10^{-12} to 10^{-7} Mo/yr. The line profile was deconvolved intoa low velocity component (LVC, < 40 km/s) and a high velocity component (HVC, >40 km/s ), originating from slow winds and high velocity jets, respectively.The LVC is by far the most frequent component, with a detection rate of 77%,while only 30% of sources have a HVC. The [OI]6300 luminosity of both the LVCand HVC, when detected, correlates with stellar and accretion parameters of thecentral sources (i.e. Lstar , Mstar , Lacc , Macc), with similar slopes for thetwo components. The line luminosity correlates better with the accretionluminosity than with the stellar luminosity or stellar mass. We suggest thataccretion is the main drivers for the line excitation and that MHD disc-windsare at the origin of both components. In the sub-sample of Lupus sourcesobserved with ALMA a relationship is found between the HVC peak velocity andthe outer disc inclination angle, as expected if the HVC traces jets ejectedperpendicularly to the disc plane. Mass loss rates measured from the HVC spanfrom ~ 10^{-13} to ~10^{-7} Mo/yr. The corresponding Mloss/Macc ratio rangesfrom ~0.01 to ~0.5, with an average value of 0.07. However, considering theupper limits on the HVC, we infer a ratio < 0.03 in more than 40% of sources.We argue that most of these sources might lack the physical conditions neededfor an efficient magneto-centrifugal acceleration in the star-disc interactionregion. Systematic observations of populations of younger stars, that is, class0/I, are needed to explore how the frequency and role of jets evolve during thepre-main sequence phase.

Connection between jets, winds and accretion in T Tauri stars: the X-shooter view