Production Practices and Quality Assessment of Food Crops. Vol. 1

conditions followed by sudden high moisture or heavy irrigation after the dry period
also leads to cracking. Too rapid growth at high nitrogen levels will lead to coarse,
loose heads, poor processing and storage quality and cracking. Cracking may also
occur as a result of boron deficiency in the soil.
4.3.4. Blindness
Blindness may result from planting blind seedlings from the beginning. The apical
meristem is damaged or is missing from the beginning. Physical damage to the
growing tip will result in cabbages that will not head due to the absence of the
shoot tip. Freezing injury during the initial stage of head formation may lead to
blindness (Yamaguchi, 1983). According to Rice and Tindall (1983) temperatures
higher that 24 °C hinder head formation and may also lead to blindness.
4.3.5. Foul smell
Very dry conditions cause the cabbage leaves to be tough and rough and the cabbage
produces a typical strong cabbage smell when cooked. The leaves are supposed to
be tender and slightly succulent as cabbage is generally consumed fresh and raw
in salads. As a heavy feeder cabbage requires higher nitrogen content than other
vegetables. If this is lower than its requirements yields are drastically reduced,
storage life shortened, maturity delayed and there is an increase in the ‘cabbagey’
flavour (foul smell) which is undesirable (Cantwell and Suslow, 2001).
4.3.6. Tip burn
Leaf margins become brown and papery later turning dark brown to black and finally
necrotic. Injured tissue becomes predisposed to attack by soft rot bacteria. Tipburn
mainly due to localized Ca 2+ deficiency in the head that can be enhanced by several
environmental conditions. The Ca 2+ can be unavailable due to drought or water
logging in the soil or when soil fertility is too high due to high levels of N, K
and Mg (http://www.cals.ncsu.edu/sustainable/peet/profiles/ppleafy.html). This
disorder is believed to be very similar to blossom end rot in tomatoes in not only
its causes but also the environmental factors affecting. Conditions favouring include
fluctuating growth rates especially rapid growth caused by high temperatures, light
intensities and excess nitrogen (http://www.cals.ncsu.edu/sustainable/peet/profiles/
ppleafy.html). Late harvesting and wide spacing of crop in the field can also increase
the incidence of this disorder.
4.3.7. Oedema
Effect of Preharvest Factors 27
These are wart-like swellings that appear mainly on the underside of leaves of
cabbage. Over-watering or prolonged rainy weather cause such swellings.