  We present the first light curve analysis of Population II novae that
appeared in M31 globular clusters. Our light curve models, based on the
optically thick wind theory, reproduce well both the X-ray turn-on and turnoff
times with the white dwarf (WD) mass of about 1.2 Mo for M31N 2007-06b in Bol
111 and about 1.37 Mo for M31N 2010-10f in Bol 126. The transient supersoft
X-ray source CXO J004345 in Bol 194 is highly likely a nova remnant of 1.2 --
1.3 Mo WD. These WD masses are quite consistent with the temperatures deduced
from X-ray spectra. We also present the dependence of nova light curves on the
metallicity in the range from [Fe/H]=0.4 to -2.7. Whereas strong optically
thick winds are accelerated in Galactic disk novae owing to a large Fe opacity
peak, only weak winds occur in Population II novae with low Fe abundance. Thus,
nova light curves are systematically slow in low Fe environment. For an
extremely low Fe abundance normal nova outbursts may not occur unless the WD is
very massive. We encourage V or y filter observation rather than R as well as
high cadence X-ray monitorings to open quantitative studies of extragalactic
novae.
