Internal CO2 concentrations in onion bulbs at different storage temperatures and in response to sealing of the neck and base
Kil Sun Yoo, Craig R. Andersen and Leonard M. Pike
Postharvest Biology and Technology Vol: 12 Issue: 2 Vol: 12 Issue: 2 Pages: 157-163.
1997
บทคัดย่อ
Internal CO2 concentrations were measured in onion (Allium
cepa L. cv. TG 1015Y) bulbs stored at 1, 7, 13, 20, 27, or 34°C
for 12 weeks and their relationships with shoot growth and respiration rates
were investigated. Maximum shoot growth was observed at 13 and 20°C.
Respiration rates were greatest at 13 and 20°C for 8 weeks, then linearly
increased with storage temperatures after 12 weeks. Internal CO2
concentrations ranging from 2 to 5% increased with increasing storage
temperatures, while internal gas volume decreased. Bicarbonate concentrations
in outer scales ranged from 130 to 190 
M
and increased with increasing storage temperatures. The centre scale tissues
contained 11¯17% CO2 , which paralleled
respiration rates. Sealing the neck area of onion bulbs stored at 1 or 27°C
significantly increased internal CO2 concentrations, but had no
effect on inhibiting shoot growth. Internal CO2 concentrations
appeared to be regulated by gas exchange rates through the neck area and/or
elevated HCO3- concentrations in outer scales. Elevated
internal CO2 concentrations or high levels in centre scale tissues
did not appear to be a primary reason for inhibited shoot growth at high
storage temperatures. There seems to be thermo-dormancy controlling shoot
growth and respiration in onion bulbs.