In this contribution we discuss the use of the surface Li abundance in lower
RGB stars as alternative diagnostic of the primordial Li abundance. These stars
are located in the portion of the RGB after the completion of the First
Dredge-Up and before the extra-mixing episode occurring at the RGB Bump
magnitude level. They are sensitive to the total Li content left at the end of
the Main Sequence phase and are significantly less sensitive to the efficiency
of atomic diffusion when compared with dwarf stars. We analysed lower RGB stars
in the Galactic Halo and in the globular clusters NGC 6397, NGC 6752 and M4.
The final estimates of initial A(Li) span a narrow range of values (between
2.28 and 2.46 dex), in good agreement with the Spite Plateau and confirming the
discrepancy with the values obtained from the standard Big Bang nucleosynthesis
calculations.Comment: 7 pages, 3 figures, 1 table, to appear in the proceedings of 'Lithium
in the Cosmos', Paris, Feb. 27-29, 2012, Memorie della Societa' Astronomica
Italiana Supplement