Salt stress is a limiting factor for cultivation in fruit crops

1. Ankit Kumar Pandey
Ph. D. Research Scholar
Horticulture (Fruit and Fruit Technology)
BAU, Sabour, Bhagalpur, Bihar
Salt Stress in Perennial Fruit
Plants
Presentation
on

2. Salt Stress
 Salt affects 7 % of world land area, which amounts to 930
million hectares.
 Saline soils occur in arid and semi-arid regions, where
amount of rainfall is insufficient for leaching
 Due to high evaporation of soil moisture, salts accumulate
in the surface of soil.
 Salinity problem is very rare in heavy rainfall areas due to
downward movement of salts in the groundwater.
 Agricultural lands that have heavily irrigated are highly
saline.
 Saline soils extensively occur in Punjab, Haryana, Uttar
Pradesh, Gujarat, W. B., T. N., K. R., and Rajasthan.

3. Salinity Soil
 Soils with- electrical conductivity (EC) - >4 dS m−1
exchangeable sodium percentage
(ESP) <15
pH - < 8.5.
 Presence of white crusts of salts on the surface
 Soluble salts – like sodium, calcium and
magnesium with low amounts of potassium and
anions, chloride, sulphate and sometimes nitrate.
 India’s share - land resources of the world 2%, on
which 18% of the world’s population and over 15%
of the world’s livestock survive.
 As per ministry of Agriculture (GOI) -In India -8.5
mha lands reported to be saline soil. Mostly found
in Indo-Gangetic plains, arid regions and coastal
areas.

4. Difference between Alkalinity and Salinity

5. Salt Tolerate Fruit Crops

6. Effect of Salt Stress on Crop Growth and Development
Germination
 Increased osmotic pressure of the soil solution
which restricts the absorption and entry of water
into the seeds.
 Certain salt constituents are toxic to the embryo
and seedlings. Anions like CO3, NO3, Cl-, SO4 are
more harmful to seed germination.
 Salt stress hampers the metabolism of stored
materials. Protease, enzyme catalyzes the
solubility of proteins to soluble nitrogen in seeds
is inhibited by salinity.

7. Photosynthetic
 Accumulation of high concentration of Na2 and Cl- in
chloroplast, photosynthesis is inhibited. Since
photosynthetic electron transport appears relatively
insensitive to salts, either carbon metabolism or
photophosphorylation may be affected
Vegetative growth
 Due to accumulation of more ions in the soil as well as
in the root zone, plants are unable to absorb water and
thus water deficit stress condition is occurred in plants,
which is termed as physiological drought.
 During vegetative stage, salt induced water stress
causes closure of stomata leads to reduction in CO2
assimilation and transpiration.
 Reduced turgor potential affects the leaf expansion.
Because of reduction in leaf area, light interception is
reduced, photosynthetic rate is affected which coupled

8. Reproductive growth and yield
 Under salt stress condition, the onset of flowing is
delayed due to the limitations of source size.
 Due to high deposition of salts in tissues, most of
the metabolic processes such as synthesis of
proteins, amino acids, sugars, starch and other
organic compounds are altered.
 Therefore the development of reproductive
structures and further maturation processes are
very much affected which ultimately diminish the
crop yield.
 Due to imbalance of nutrients under salt stress,
hormone synthesis is hampered leads to reduction
in quantity as well as quality of crop produce

9. GENERAL SIGNS OF SALT STRESS –
Plants on the basis of adaptive evolution can be classified roughly into two major types
HALOPHYTES
 Plants that can survive and
reproduce in environments with high
salt concentration (200 mM NaCl)
 These plants constitute about 1% of
the world's flora.
 Halophytes can be classified as
“natural” and plants that tolerate salt
but do not normally live in saline
conditions (Patane et al., 2012).
GLYCOPHYTES
 The plants that cannot withstand
salinity and eventually die.
 The general signs of salinity include
reduction in total leaf area, indeed,
decreased leaf growth is the earliest
response of glycophytes exposed to
salt stress (Munns et al., 1986),
marginal and tip burning of leaves,
followed by yellowing and bronzing.

10. Salt Tolerance Mechanisms
Salt Avoidance
Some fruit plants have the
avoidance mechanism in which the
reduction in the canopy area may
be considered as an avoidance
mechanism, which minimises
water loss by transpiration when
the stomata are closed.
Salt Exclusion
Prevents the entry of salts into the
vascular system. Na+ and Cl-
exclusion by roots ensures that
Na+ and Cl- do not accumulate to
toxic concentrations in leaves.
Salt Excretion
Halophytes can survive in the
presence of high NaCl
concentrations (300–500 mM)
because they have developed
better salt resistance mechanisms
viz. salt-secreting glands and hairs
actively eliminate salts, thus
keeping the salt concentration in
the leaves beneath a certain
threshold.

11. Osmotic Adjustment
The osmotic adjustment, i.e., reduction of cellular osmotic
potential by net solute accumulation, has been considered
an important mechanism to salt and drought tolerance in
plants. This reduction in osmotic potential in salt stressed
plants can be a result of inorganic ion (Na+, Cl-, and K+)
and compatible organic solute (soluble carbohydrates,
amino acids, proline, betaines, etc) accumulations
(Hasegawa et al., 2005). However these changes are only
any few initial responses of many others occurred from salt-
stressed seedlings. Likewise Higher salt tolerance due to
higher capacity of osmotic adjustment (high proline) was
found in Sour Orange and Attani-1 than Troyer citrange and
Billikhichlli.
Antioxidant Defensive System
Salinity tolerance is positively correlated with the activity of
antioxidant enzymes, such as superoxide dismutase (SOD),
catalase (CAT), glutathione peroxidise (GPX), ascorbate
peroxidise (APX), and glutathione reductase (GR) and with
the accumulation of non-enzymatic antioxidant compounds
salt stress induces the increased activities of SOD, CAT,
Ascorbate peroxidase and GR in Karna khatta having higher

12. Salinity Tolerance Strategies
Traditional Approaches
 better irrigation practices- such as drip irrigation,
to optimize use of water can be employed.
 In rain-fed agriculture-practices such as rotation
of annual crops with deep-rooted perennial
species may restore the balance between rainfall
and water use, thus preventing rising water tables
bringing salts to the surface.

13. Leaching
 Leaching excess salts and maintaining a favourable
salt balance remains the best strategy to prevent
detrimental salt accumulation in the soil profile.
 Since soil salinity makes it more difficult for plants to
absorb soil moisture, these salts must be leached out
of the plant root zone by applying additional water.
This water in excess of plant needs is called the
leaching fraction (Grattan, 2002).

14. Rootstocks For Salinity Tolerance

15. Cope Up The Salt Stress Problem
A. Conventional Approaches:
 Development of stress tolerant rootstocks
 Development of stress tolerant fruit varieties
B. Biotechnological Approaches
 Somaclonal variations.
 Somatic hybridization
 Use of Molecular Marker

16. Thank You