This document discusses physiological disorders that can occur in longan fruits, including: 1. Browning of the pericarp can occur at temperatures between 20-30°C within 24 hours of harvest due to water loss. Packaging the fruits can help reduce water loss and browning. 2. Fruit cracking is more common in early cultivars and is caused by low humidity, high temperatures, and hot winds during fruit development. Maintaining soil moisture through irrigation and mulching can help minimize cracking. 3. Prolonged storage and overmaturity can cause aril breakdown, softening, loss of turgidity and flavor, starting at the blossom end and moving to the stem end.

2. Longan Physiological Disorders
A
Lecture To ToT trainees ( FFS)
By
Mr. Allah DadKhan
Provincial Coordinator IPM KPK
MINFAL Pakistan

3. SYMPTOMS
 Browning of the pericarp
occurs at ambient
temperatures of 20-30°C
within 24 hours of harvest.
Water loss (desiccation) of
litchi results in brown spots
on the bright-red shell
(pericarp). Under severe
conditions or prolonged
exposure, packaging in
polymeric films reduces water
loss and browning severity
FRUIT CRACKING

4.  Fruit cracking is one of the major limiting factors in the cultivation
of lychee, especially early cultivars (Singh, 1986).The early
varieties are more prone to the problem of fruit cracking in
comparison to late cultivars.The low atmospheric humidity, high
temperature and hot winds during fruit development and maturity
stage favour fruit cracking. Light irrigation to maintain soil
moisture and to improve humidity has been found to minimize
this problem through maintenance of a better micro-climate.
Mulching with farm residues and 3 irrigations significantly reduced
the cracking (Singh, 1986) in a trial conducted on the cultivar
Shahi. In addition, spraying with either 100 ppm NAA or 0.2
percent borax during the developing stage of the fruits has been
found to be highly effective in checking the cracking.

5.  Water loss (desiccation) of lychees results in
brown spots on the bright-red shell (pericarp).
Under severe conditions or prolonged exposure,
the spots enlarge and coalesce until the surface
is completely brown.The flavor of the arils
within browned fruit may or may not be
adversely affected. Packaging in polymeric films
reduces water loss and browning severity.

6.  Symptoms include pericarp browning (similar
to that caused by water loss) and increased
susceptibility to decay. Storage at 1°C (34°F)
for 12 days before transfer to 20°C (68°F) for
one day resulted in pericarp browning

7.  Incidence and severity of cracking depend on
cultivar and desiccation during storage.
Cracks provide an entry way for decay-
causing pathogens.

8.  Prolonged storage and overmaturity may
cause aril breakdown (softening, loss of
turgidity, translucency) and loss of flavor
beginning at the blossom end and spreading
to the stem end.