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Fig. 4.47. A summary of the effects on garlic sprouting, bulbing and flowering of
temperatures during storage and of temperatures and photoperiods after planting.
Flowering
The discovery of seed-fertile garlic in central Asia (Etoh and Simon, 2002) raised
the possibility of improving garlic using conventional crossing rather than
clonal selection and has increased interest in how to achieve normal flower
development in garlic. This is not easy, since ten millennia of selection for bulbs
have resulted in the suppression of florigenesis. Garlic genotypes vary con-
siderably in their ability to produce scapes, umbels, fertile pollen and receptive
stigmas (Etoh and Simon, 2002: Kamenetsky et al. , 2003). As discussed above,
inflorescences are induced by subjecting plants or stored bulbs to low
temperatures (-2 to 2°C optimum in Japanese cultivars (Takagi, 1990)). The
differentiation of inflorescences did not occur within the stored bulb (see Fig.
2.18) but after planting, in the study by Kamenetsky and Rabinowitch (2001).
Inflorescence differentiation following low temperature induction is favoured by
growth in relatively cool temperatures and short photoperiods (e.g. below 13°C
and 12 h for Japanese cvs). These conditions cause slow inflorescence initiation
and emergence, but they slow bulbing more than inflorescence formation. As
with onion, inflorescence development and bulbing 'compete' during this phase
so that bulbing, which is favoured by long photoperiods and high temperature,
tends to prevent or arrest inflorescence emergence.
Various degrees of arrested inflorescence development are commonly seen in
garlic, ranging from a vestigial flower stalk within an apparently normal bulb,
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