Chlorine cycle in the environment, absorption of chlorine by plants, its structural and functional role in plants.

2. Chlorine
Structural & Functional Role
Deficiency Symptoms
Chlorine Cycle

3. Submitted By:
Muhammad Ahsan Jamil

4. What is Chlorine?
• Chlorine is one of the halogen elements belonging to group 17
of the periodic table.
• The atomic number of 17, an atomic mass of 35, five oxidation
states (–1, +1, 3, 5 and 7), of which the -1 state is most common
in nature.

5. What is Chlorine?
Chlorine has two naturally occurring isotopes (35Cl and 37Cl),
of which 35Cl comprises 76% of the total mass. Chlorine is a
greenish-yellow gas that is slightly soluble in water. Chlorine
has a suffocating odor. (Kaufmann 1999b).

6. Functional Role of Chlorine
Chlorine performs many functions in plant body, including
• Osmoregulation
• Stomatal Opening
• O2 evolution during Photosynthesis

7. Functional Role of Chlorine
• Chloride diminishes the effects of fungal infections
• Chloride competes with nitrate uptake, tending to promote the use of
ammonium nitrogen. Lowering nitrate uptake may be a factor in chloride’s
role in disease suppression, since high plant nitrates have been associated
with disease severity

8. Sources of
Chlorine in soil
• Natural inputs of Cl to soils come mainly
from rainwater, sea spray, dust, and air
pollution.
• In addition, human practices, such as
irrigation and fertilization, contribute
significantly to Cl deposition.
• The rates of Cl deposition to soils range
from 1 to >1000 kg ha−1, depending on
location and cultural practices (White and
Broadley, 2001)

9. Chlorine Distribution in
plants:
• Chlorine, existing in plants mainly as Cl−
anion, is distributed in the vegetative
organs such as the shoots and leaves.
• The amount of Cl− in the nutritional
organs is more than 80% of the total
amount, and it accumulates more in the
lower layer leaves or the elder leaves than
the upper or the younger ones (Li et al.,
2002).

10. Continued
• There is limited Cl, varying from 1.0% to 2.9%, accumulated in plant seeds.
• Johnson et al. (1957) suggested a critical Cl concentration in plant tissue of
approximately 0.1 g kg−1.
• Tang et al. (1996) found that the distribution sequence of Cl in cotton was:
leaf > stem > root > seed > fiber.
• In lettuce it was: leaf > shoot > root.

12. Components of Chlorine Cycle
• The global chlorine cycle is now usually divided into the following major
reservoirs of chlorine interconnected by pathways of exchange:
• The atmosphere
• The Volcanic emissions
• The oceans, rivers, lakes etc.
• The air pollution (CFCs)
• The Earth's interior, carbon from the Earth's mantle and crust.

13. The mechanisms involved in the chlorine cycle
are as follows :
• Movement of marine NaCI + aerosols from atmosphere to hydrosphere and
lithosphere through sedimentation, rain and wind action.
• Movement of HCI, CI, C10 and NH4C1 aerosols from atmosphere to
Lithosphere and hydrosphere –through volcanoes, rain and sedimentation.
• Transformation of chlorocarbons and chlorofluoro-carbons into other
atmospheric compounds by stratospheric decomposition.

14. Continued:
• Transformation of biospheric, lithospheric and hydrospheric chloride into
chlorofluoro-carbons by fermentation, combustion, marine algae,
refrigerators, etc.
• Movement of chlorides between biosphere, hydrosphere and lithosphere
through biological decay, plant roots and marine organisms.

15. Toxicity symptoms of Chlorine
• Toxic symptoms are similar as is found with typical salt damage.
• Leaf margins are scorched and abscission is excessive.
• Leaf/leaflet size is reduced and may appear to be thickened.
• Overall plant growth is reduced. Chloride accumulation is higher in older
tissue than in newly matured leaves.
• In conifers, the early symptoms are a yellow mottling of the needles,
followed by the death of the affected needles.

17. Deficiency symptoms of Chlorine
• Wilting, restricted and highly branched root system, often with stubby tips.
• Leaf mottling and leaflet blade tip wilting with chlorosis has also been
observed.
• bChloride insufficiency in cabbage is marked by an absence of the cabbage
odor from the plant

19. Chlorine Fertilizers
Material Formula Percent Cl
Sodium Chloride NaCl 61%
Potassium Chloride KCl 47%
Calcium Chloride CaCl2 64%