Respiration rate, Q10, firmness and dry weight are presented in
Table 1. Respiration rate was significantly higher in purple and
yellow local landraces at 20 C. Measurement of respiration rate is
useful when investigating the physiology of many vegetables
(Kader, 1986). A continuously high rate of respiration is often
associated with a shortened shelf life (Day, 1990). The Q10 value,
which indicates the n-fold decrease in shelf life caused by a 10 C
temperature increase (Labuza, 1982), was significantly higher in all
local landraces, especially in the purple and yellow types. As reported
by Kader (2002), Q10 is inversely correlated with shelf life.
These results were confirmed by firmness measurements. Commercial
carrots showed a mean firmness 28% higher than local
landrace carrots (Table 1). This difference could be attributed to the
higher dry weight of commercial types in comparison with orange,
yellow and purple carrots (Table 1). All these results indicate that
the local landrace carrots are perishable and difficult to store as raw
products.