seed germination problems

1. Power point presentation
Presented by: Anila Khalid & Qurat-ul-Ain
Presented to: Dr. Sajid Ali

2. 
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3. 
 Seed germination problems
 Stand failure
 Mixtures
 Genetic
 Weeds
Content
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4. 
Germination
 Germination in plants is the process by which a
dormant seed begins to sprout and grow into a
seedling under the right growing conditions.
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5. 
 external factors
 Also known as environmental factors
 Abiotic factors
 Water
 Air
 Temperature
 Light
 Soil condition
 Biotic factors
 Pathogenic organisms
 Internal factors
 Biotic factors
 Seed reserves
 Dormancy
 Impermeable seed coat
 Other factors
Factors Responsible For
Seed Germination
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6. 
 Deterioration of seed
 Kind/variety of the seed
 Genotypic factors
 Initial seed quality
 Effect of organisms associated with seeds
 Bacteria and fungi
 Insects and mites
 Fluctuating environmental conditions
 Oxygen pressure
 Storage life of seed
 Direct sunlight exposure on the seed
Other factors
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7. 
 Number of times and kind of fumigation
 Effect of seed treatment
 Damping off of stand seedlings
 Infestation of weeds
 Morphological changes
 Cell membrane changes
 Loss of enzyme activity
 Reduced respiration
 Increase in seed leachates
 Increase in free fatty acid content
Other factors
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8. 
External factors
 Abiotic factors
 Water
 Water is required for germination. The uptake of water
by seeds is called imbibition, which leads to the swelling
and the breaking of the seed coat.
 After the seedling emerges from the seed coat and starts
growing roots and leaves, the seedlings food reserves are
typically exhausted; at this point photosynthesis
provides the energy needed for continued growth and
the seedling now requires a continuous supply of water,
nutrients and light.
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9. 
 Abiotic factors
 Air
 Germinating seeds respire at a very high rate.
 The adequate supply of oxygen is necessary for
germination to take place and the seedlings to grow.
 Germination rate and germination percentage of most
kinds of seeds are adversely affected if the germinating
medium is poorly aerated.
 In seed-beds that are over-watered or poorly drained
with clayey soil, the soil pore spaces may be so filled
with water that oxygen supply to the seeds is retarted or
prevented.
External factors
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10. 

External factors
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11. 
 Abiotic factors
 Soil conditions
 Soil salinity and poor quality water used to irrigate the
seed beds often retard or prevent germination.
 Salinity problems become severe when the germinating
medium is lightly and frequently watered; evaporation
of water leaves salt deposits on the soil surface. Small
shallowly sown seeds are likely to be damaged by salts.
 This problem can be solved by using soils with adequate
organic matter and irrigation water low in slats, with
holding fertilizers and by irrigating more copiously but
less frequently so that excess salts are leached out.
External factors
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12. 
 Abiotic factors
 Light or darkness
 Light or darkness can be an environmental trigger for
germination and is a type of physiological dormancy.
 Most seeds are not affected by light or darkness, but
many seeds, including species found in forest settings,
will not germinate until an opening in the canopy allows
sufficient light for growth of the seedling.
External factors
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13. 
 Biotic factors
 Pathogenic organisms
 Pathogenic organisms on the seed surface, in the
germinating medium, in the irrigation water or on the
tools may cause low germination and rotting of
seedlings.
 The situation is known as damping-off and is aggravated
by high moisture and high temperature condition.
External factors
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14. 
 Biotic factor
 Seed dormancy
 In some plants the embryo is not fully mature at the time of
seed shedding.
 Such seeds do not germinate till the embryo attains maturity
 The freshly shed seed in certain plants may not have sufficient
amounts of growth hormones required for the growth of
embryo.
 These seeds require some interval of time during which the
hormones get synthesized.
 The viability period ranges from a few weeks to many years.
Seeds of Lotus have the maximum viability period of 1000
years. Seeds germinate before the ending of their viability
periods.
Internal factors
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15. 
Schematic representation of the different categories of
dormancy together with associated problems
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16. 
 Biotic factors
 Seed viability
 Factors affecting seed viability
 Causes of less viability
Internal factors
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17. 
Factors affecting seed viability Causes of less viability
Harvesting of seed Degeneration of enzyme
Duration between harvesting and
threshing
Disappearance of stored food
Methods of threshing Abnormal seed coat
Moisture content and relative
humidity of the stored seed
Loss of power to protect the
protoplasmic molecule from the inert
molecule
Age of seed Gradual coagulation of protein of
embryo
Temperature of the stored seed
Aeration in stored seed
Contaminate of the seed
Seed viability
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18. 
Seed factor for germination Field factor for germination
 viability  Good tilth
 vigor  Optimum soil moisture
 Seed age  Optimum soil
temperature
 Free from dormancy  Aeration
 Free from injury  Free from obstacle
Factors for Germination
Factors for germination
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19. 
 Some types of seeds are inherently long lived; others
are short lived, while others have an intermediate
life span owing to their differences on genetic
makeup.
 During seed production strict attention must be
given to the maintenance of genetic purity and other
qualities of seeds by introduction of new superior
crop plant varieties.
 In other words, seed production must be carried out
under standardized and well-organized condition.
Genotypic factors
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20. 
Deterioration of varieties
Developmental variation
Mechanical mixtures
Mutations
Natural crossing
Minor genetic variations
Selective influence of diseases
Techniques of plant breeders
Genetic principle
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21. 
 When the seed crops are grown
 In difficult environment
 Under different soil and fertility conditions
 Or different climatic conditions
 Or under different photoperiods
 Or at different elevation for several consecutive generations
-----the developmental variation may arise some times as
different growth response
To minimize the opportunity for such shifts to occur in
varieties it is advisable to grow them in their areas of
adaptation and growing season
1-Developmental
variation
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22. 
 To avoid this sort of mechanical contamination it
would be necessary
 To rogue the seed fields at least at the three stages
 And practice the utmost care during the seed
production, harvesting, threshing and further
handling.
2-Mechanical mixtures
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23. 
 This is not a serious factor of varietal deterioration.
 In the majority of the cases it is difficult to identify or
detect minor mutation
4-Natural crossing
 In sexually propagated crops, natural crossing is
another most important source of varietal
deterioration due to introgression to genes from
unrelated stocks which can only be solved by
prevention.
3-Mutations
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24. 
Natural crossing with undesirable
types
Natural crossing with diseased plants
Natural crossing with off-type plants
Natural crossing occurs
due to following three
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25. 
The breeding system of species
Isolation systems
Varietal mass
Polling agent
Size of the pollen grain
Duration of pollen viability
Natural crossing occurs
due to following factors
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26. 
 Minor genetic variations may exist even in the
varieties appearing phenotypically uniform and
homogenous at the time of their release.
 During later production cycle some of this variation
may be lost because of selective elimination by the
environment
 To overcome these yields trials are suggested.
5-minor genetic
variations
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27. 
 The selective influence of disease in varietal
deterioration is also of considerable importance
 New crop varieties often become susceptible to new
races of diseases often caused by obligate parasites
and are out of seed programs
 Similarly the vegetatively propagated stocks
deteriorate fast if infected by viral, fungal and
bacterial diseases.
 During seed production it is, therefore, very
important to produce disease free seeds/stocks.
6-selective influence of
diseases
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28. 
 In certain instances, serious instabilities may occur in
varieties due to cytogenetically irregularities not
properly assessed in the new varieties prior to their
release.
 Other factors, such as
 Breakdown in male sterility
 Certain environmental conditions
 And other heritable variations
-------May considerably lower the genetic purity.
7-Techniques of plant
breeders
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29. 
 Most important source of variety deterioration take place
 At sowing time if more than 1 variety is sown with same
drill
 During harvesting & threshing operations
 Gunny bags, seed bins, elevators, etc. are connected with
seeds of other varieties
 Solution
 rogue the seed fields
 Care during seed production, harvesting, threshing &
further handling.
Mechanical mixtures
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30. 
 The presence of weed seeds at time of crop harvest
leads to mixing of weed seeds with crop seeds. In
many instances it is difficult to remove them during
the processing of seeds.
 The presence of weeds in the seed field or nearby
areas may serve as host to no. of diseases. Good &
effective weed control therefore would be necessary
to obtain good seed yields & to avoid contamination.
Weed control
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31. 
 Faulty germination and wide gap cause weed crop
competition intense
 Weed seeds germinate readily while crop emergence
at longer intervals, which leads to severe weed crop
competition, hence adequate seed rate, use of good
quality seed and growing quickly germinating crop
in weed susceptible crop in weed susceptible area,
have to be practiced.
Weed crop interference
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32. 
 It has been recognized as a definite disease
responsible for poor germination and stand of
seedling in nursery bed.
 The disease may be physiological(caused by
physiological disorder) or Pathogenic(caused by
microorganisms mostly fungi).
 The seedlings of ornamental and vegetable plants,
field crops, and forest trees in nurseries all are liable
to be affected.
Failure of stand seedling
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33. 
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