  The non-local thermodynamic equilibrium (NLTE) line formation of neutral
boron in the atmospheres of cool stars are investigated. Our results confirm
that NLTE effects for the B I resonance lines, which are due to a combination
of overionization and optical pumping effects, are most important for hot,
metalpoor, and low-gravity stars; however, the amplitude of departures from LTE
found by this work are smaller than that of previous studies. In addition, our
calculation shows that the line formation of B I will get closer to LTE if the
strength of collisions with neutral hydrogen increases, which is contrary to
the result of previous studies. The NLTE line formation results are applied to
the determination of boron abundances for a sample of 16 metal-poor stars with
the method of spectrum synthesis of the B I 2497 A resonance lines using the
archived HST/GHRS spectra. Beryllium and oxygen abundances are also determined
for these stars. The abundances of the nine stars which are not depleted in Be
or B show that, no matter the strength of collisions with neutral hydrogen may
be, both Be and B increase with O quasi-linearly in the logarithmic plane,
which confirms the conclusions that Be and B are mainly produced by primary
process in the early Galaxy. The most noteworthy result of this work is that B
increases with Fe or O at a very similar speed as, or a bit faster than Be
does, which is in accord with the theoretical models. The B/Be ratios remain
almost constant over the metallicity range investigated here. Our average B/Be
ratio falls in the interval [13+-4, 17+-4], which is consistent with the
predictions of spallation process. The contribution of B from the nu-process
may be required if the 11B/10B isotopic ratios in metal-poor stars are the same
as the meteoric value.
