Agriculture Reference
In-Depth Information
Fig. 7.8. Sprouting, respiration rate and internal CO
2
concentrations in bulbs of
onion cv. 'Texas Grano 1015Y' stored at different temperatures after 4 (
●
), 8 (
) or
12 (
) weeks. The error bars show standard deviations based on ten replicates. (a)
Internal shoot lengths. (b) The respiration rate of the centre scales. (c) Internal CO
2
concentration (A) and internal gas volume (B) (from Yoo
et al
., 1997. Courtesy of
Postharvest Biology and Technology
).
The rate of sprouting is more rapid in bulbs transferred from 0 or 5 to 25°C
than in those kept continuously at 25°C (Tanaka
et al.
, 1985a). Bulbs stored at
25°C for 5 months and then transferred to 2°C subsequently had a lower
respiration rate than those stored at a constant 2°C (Ward, 1976). The reasons for
these effects are not known, but they do indicate that some long-lasting
dormancy-enhancing process is engendered by storage at 25-30°C. Storage at
these temperatures also inhibits cytokinin activity (see below), has a devernalizing
