physiological disorder in plants

1. Physiological
disorders in
crop plants

2. Introduction
Physiological disorders are those
problems resulting from the influence of
environmental and cultural factors on
plant growth
The main causes are:
• Nutrient deficiencies
• Excess fertilizers
• Low temperature and frost
• High temperature
• Lack of light
• Overwatering
• Under watering
• High concentration of CO2

3. Nutrient
Deficiency
physiological
disorders
Symptoms include:
Stunted
growth
Chlorosis
Interveinal
chlorosis
Purplish-
red
colouring
Necrosis
Lack of plant nutrients or the presence
of nutrients at levels toxic may lead to
physiological disorders in plants
Nutrients are chemical elements
required by plants for growth and
development

4. Nitrogen deficiency
 Younger leaves become pale green and
the older leaves turns yellow eventually.
 leaves that will eventually turn brown and
die.
 Plant growth is slow, plants will be stunted,
and will mature early.

5. Phosphorous deficiency
 Plant growth will be slow and stunted, and the
older leaves will have a purple coloration,
particularly on the underside.

6. Potassium deficiency
 On the older leaves, the edges will look burned,
a symptom known as “scorch”.
 Plants will easily lodge and be sensitive to
disease infestation.
 Fruit and seed production will be impaired and
of poor quality.

7. Blosson end rot
 Physiological disorder in tomatoes and pepper
due to deficiency of calcium.
 Tissue typically at the blossom end turns brown
and then black and becomes sunken and
leathery

8. Bitter pit in apple
 Bitter pit is a disorder in apple induced by
calcium deficiency. It occurs commonly in
 The affected fruit have dark spots about 0.5 cm
diameter which occur on the skin and/or in the
flesh.
 The cells in the spots are necrotic and turn
brown black

9. Magnesium deficiency
 Older leaves will be yellow in color with
interveinal chlorosis (yellowing between the
veins) symptoms.
 Plant growth will be slow and some plants may
be easily infested by disease.

10. Sulfur deficiency
 A general overall light green color of the entire
plant with the older leaves being light green to
yellow in color as the deficiency intensifies.

11. Hen and chicken disorder
 This disorder is cause by the deficiency of
boron resulting in more number
of undeveloped round or oblate short berries
with few berries attaining the normal shape
characteristic of the variety.

12. Internal black rot
 Lesions are typically tan, roughly circular, and
approximately 1/8 of an inch in diameter
 Deficiency of boron
 Underlying cause is cell death

13. Chlorine deficiency
 Younger leaves will be chlorotic and plants will
easily wilt.

14. Copper deficiency
 Plant growth will be slow and plants stunted
with distortion of the young leaves and death
of the growing point.

15. Iron deficiency
 Interveinal chlorosis will occur on the emerging
and young leaves with eventual bleaching of
the new growth.
 When severe, the entire plant may be light
green in color.

16. Whiptail
 Caused due to the deficiency of molybdenum
 In young plants the deficiency symptoms are
chlorosis of leaf margins and the whole leaves
turn while
 The leaf blades do not develop properly. When
the deficiency is severe, only the midribs
develop

17. Excess
Fertilizer/
Nutrients
When fertilizers are present at too high-
level roots are scorched and are unable to
provide nutrients for the other parts of the
plants often resulting in the plants death
Manganese toxicity: yellowing of margins
of older leaves; poor root development
Chloride toxicity: premature yellowing of
young leaves, marginal or tip necrosis of
older leaves, caused by saline water and
soil condition
Ammonium toxicity: poor emergence
followed by wilting and death of seedlings;
browning of central root tissue etc

18. Manganese toxicity
 It causes new leaves to become pale and
rapidly develop light necrotic areas on leaf
margins near the apex that move towards the
midrib between the veins
 This necrosis can appear as fine pinpoint spots
on tendril leaves
 As the toxicity increases some leaves develop
severely necrotic tips and margins that shrivel
leaving the leaf cupped

19. Chloride toxicity
 Symptoms are similar to typical salt damage
 Leaf margins are scorched and leaf size is
reduced and appear to be thickened
 Overall plant growth is reduced
 Chloride accumulation is higher in older tissues
than in newly matured leaves

20. Ammonium toxicity
 Plants fertilized with ammonium-nitrogen
(NH4- N) may exhibit ammonium-toxicity
symptoms. Lesions may occur on plant stems,
there may be a downward cupping of the
leaves, and a decay of the conductive tissue at
the base of the stem with wilting of the plants
under moisture stress. Blossom-end rot of fruit
will occur and Mg deficiency symptoms may
also occur.
 Poor emergence followed by wilting and death
of seedlings; browning of central root tissue etc

21. Vegetable splitting
 Roots get splitted making it unfit for market.
Root splitting increases with soils having high
content of nitrogen and also with higher
concentration of ammonium compounds

22. 3.Low temperature and frost
 Plants differ in their tolerance to low
temperature. Low temperature slow down
plant’s growth
 Frost often causes the above-ground parts of
sensitive plants to collapse into a mess of green
tissue after ice has formed inside the plant and
fractured all the cells

23. Leaf chlorosis and frost banding
 Chlorosis was caused by a disruption of
chloroplasts caused by winter cold. Green
chlorophyll pigments are often converted in to
yellow pigment namely chlorophyllins. Leaf may
appear with distinct bleached bands across the
blade of young plants called frost banding
 eg: sugarcane, wheat and barley.

24. Leaf necrosis and malformations
 Spring frost causes various types and degree of
injury including cupping, crinkling finishing and
curling of leaves of apple trees and stone fruits.
The distortion is caused by death of the
developed tissues before the expansion of
leaves.

25. Stem disorders
 Frost cracks develop when tree trunk or limps
lost their heat too rapidly. The outer layer of
bark and wood cool most rapidly and subjected
to appreciable tension causing marked
shrinkage and cracking following a sudden
temperature drop. Affected timber of poor
quality.

26. 4. High temperature
 1. Leaf scorch
High temperature causes leaf scorch directly or indirectly
by stimulating excessive evaporation and
transpiration. Tip burn of potato is a widespread
example for this disorder.
Maize: Marginal scorching

27.  2. Sunscald
In leaf vegetable crops like lettuce and cabbage,
when leaves on the top of the head are exposed to
intense heat, water soaked lesions or blistered
appearance occur These irregular shaped areas
become bleached and parched later

28.  3. Water core
In fruit crop like Tomato, exposure to high
temperature causes death of the outer cells of
fruit skin. Subsequently corky tissue occurs
beneath the skin, with watery appearance of
the flesh near the core of the fruits faster. Often
light stress is coupled with heat stress eg. sun
scald of bean, sun burning of soybean and
cowpea. In flower crop like chrysanthemum,
increase in light intensity affects flower bud
formation. Reproduction phase does not
commence and modified into leaf like bracts.
Pear: Water core

29. 5.Lack of light
 Adverse light intensity causes impaired growth
and reduced vigour.
 Subsequently leaves gradually lose green
colour, turning pale green to yellow, stems may
dieback little every year.
 Insufficient light limits photosynthesis, causing
food reserves to be depleted.

30. 6.Overwatering
Overwatering replace the air
spaces in soil thus preventing
root respiration which is
needed to supply energy for
root growth and nutrient
uptake.
Overwatering symptoms may
include
The lower leaves turn yellow
and drop
New foliage may have brown
spots
The whole plant may become
stunted and stems and roots
become brown and decayed
Flower structure is deteriorated

31. 7.Underwatering
 The plant needs sufficient water to carry
nutrients around to transpire from the leaf in
order to keep a desirable leaf temperature and
to maintain turgidity in some plant tissues
 In some plants leaves changes from shiny to
dull as a first signal of water stress and also may
change from bright green to grey green
 Flowers may fade quickly and fall prematurely
 Water should be applied as per requirements of
the plants

32. 8.High concentration of co2
 High concentration of CO2 is generally
beneficial for growth and provide maximum
benefit between 0.1 and 0.2 Kpa
 Photosynthetic activity actually reduces when
CO2 concentration exceeds optimal level so
plant may turn yellow
 Plants which are sensitive to higher levels of
CO2 should not be grown in closed
environments