Presented By: Dhaval Bhanderi

1. Course Name: SEED PATHOLOGY (2+1)
Topic: Management of Seed - Borne Plant Pathogens/
Diseases and Procedure for Healthy Seed Production
Submitted to :
Dr. D.S.Kelaiya
Associate Research Scientist (Pl.Path.)
Main Oilseeds Research Station
Junagadh Agricultural University
Junagadh
Submitted by :
Dhaval Bhanderi
M.Sc.(Hons.) Agriculture
1st
Sem

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Management of Seed - Borne Plant Pathogens/
Diseases
❖ The top five control methods against seed borne pathogens are:
1. Regulatory Methods
2. Cultural Methods
3. Physical Methods
4. Chemical Methods
5. Biological Methods
(1) Regulatory Method:
There are certain federal and state laws which regulate the conditions for
cultivation of crop and their distribution between states and countries. This helps
preventing the import and spread of pathogen into country or individual states.
Such regulatory methods are enforced by means of quarantines, inspection
of plants in field or warehouses, and occasionally by voluntary or compulsory
eradication of certain host plants.
I. Plant Quarantine:
Plant quarantine as a practice covered two basic principles of disease
management exclusion and eradication. When germplasm is regulated by
quarantine the entry of organism and seeds with infection is prevented by
inspection and treatment or the host is banned or otherwise restricted.
The entry of plants, plant parts and their product is conditioned, regulated
and restricted at national and international levels through Plant Quarantine Acts.
The growth of quarantine regulations has been under way since 1870. Since then
each country has its own such organization.
In India, Destructive Insect and Pests Act (DIP Act) was passed by Govt., of
India in 1914. The Agricultural Pests and Diseases Acts of different states prevent
interstate spread of pests and pathogens. The plant quarantine stations are at major
sea and airports.
Pathogens are likely to introduced in or on live plants, seeds, tubers and
other planting material, in imported grain, fruit vegetables and other food stuffs, in
plant material used in industry (as cotton fibers etc.), in plant material used in
packing, and in soil or incidental plant debris present.

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The plant and their products must be imported only from disease- free areas.
Even if the material is already inspected by the quarantine services of the exporting
country, it should be rechecked at the point of import. Special precautions are
needed when cultures of pathogenic fungi, bacteria etc. are exchanged for scientific
purposes.
In extreme cases it may become necessary to prohibit the import of certain
plant material from areas where certain pathogens occur. Effective examination of
incoming plant material depends largely on having enough number of adequately
trained and experienced inspectors at ports, airports, railway stations and frontier
posts. The dramatic increase in air travel has created problems in plant quarantine.
e.g. Late blight of potato, Brown spot of rice, Downey mildew of pearl millet,
Banana bunchy top, Potato wart.
II. Inspections/Certification:
Several voluntary inspection and certification systems are also in effect in
various areas in which appreciable amount of seed, seedling nursery stock, potato
seed tubers etc. are produced. Growers interested in sale of these materials submit
for voluntary inspection and/or indexing of their crop in the field and in storage by
regulatory agency.
III. Use of Pathogen Free Seeds/Propagating Material:
Crop plants attacked by vectored viruses, mycoplasmas, fungi, bacteria and
nematodes can be protected from disease by this method. It must be ensured that
the propagating materials (seed, tubers, buds, bulbs, grafts, root stocks, corms,
cuttings, rhizomes etc.) are free from pathogens.
➢ Guidelines for Import of Germplasm (seed or others):
✓ Import from a country where the pathogen(s) is absent.
✓ Import from a country with an efficient plant quarantine service. So that
inspection and treatment is done.
✓ Obtain plant material from the safest known source within the selected
country.
✓ Obtain untreated seeds so that detection of seed borne pathogens is
facilitated.
✓ Obtain clean healthy looking seeds free from impurities.
✓ Obtain an official certificate of freedom from pests and diseases from the
exporting country.

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✓ Import the smallest possible amount of planting material, the smaller the
amount the less the chance of its carrying infection. It will also simplify post
entry inspection.
✓ Inspect material carefully on arrival and treat.
✓ If other precautions are not adequate, subject the material to intermediate or
post entry quarantine.
➢ Problems in Plant Quarantine:
Quarantine serves as a filter against the introduction of hazardous pathogens
but still pathogens are introduced.
Possible reasons are that:
• It is difficult to detect all types of infectious pathogens by conventional
methods.
• The latent infection may pass undetected under post entry quarantine.
• Destruction of all infected or suspected material.
• Lack of sensitive methods for testing fungicide treated seeds.
• Plant pathogens may be introduced on inert material such as packing
material, dried root bits, plant debris, soil clods etc.
(2) Cultural Methods:
Adjustment of crop management procedures has been an age old practice
with the farmers for prevention of losses in crops due to diseases and other causes.
It is an integral part of subsistence agriculture in developing countries. Cultural
practices are now being considered as essential back up procedures for
management of resistant varieties and also for chemically protected crops.
For development of a disease, contact between the host and the parasite must
occur in an environment that is favourable for the pathogen and pathogenesis.
Suitable modification in cultural practices can modify the environment that is not
favourable for the pathogen but favourable for the host
On this basis disease control by cultural practices is mainly preventive. Many
practices reduce the density and activity of the inoculum. Precautions taken under
avoidance are also mainly cultural practices. A large number of fungal, bacterial
and virus pathogens are transmitted through true seed or vegetative propagating
material. For effective disease control this source of primary inoculum must be
taken care of.

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➢ Seeds carry the pathogens as:
(i) Internally seed-borne infection,
(ii) Externally seed borne inoculum,
(iii) Contaminants with the seed, and
(iv) Through nursery raised planting stock.
Although the infested or infected propagating material can be made
pathogen free by chemical or physical treatments, production of such seed in the
field is the first and important step. Following practices are followed to produce
and use pathogen-free seed material.
I. Dry Climate for Seed Production:
Control of seed-borne diseases favoured by wet climate can be achieved by
raising the crop in dry areas. Some examples are anthracnose of bean
(Colletortichum lindemuthianum), anthracnose of cucurbits (Colletortichum
lagenarium), Ascochyta blight of pea (Ascochyta spp.).
For producing seed of such crops dry areas are preferred where leaf wetness is
avoided. Reasonably good dry climate can be created in wet areas through
management of crop canopy facilitating air circulation and entry of sun rays.
II. Isolation Distance for Seed Plots:
Separation of seed plots from sources of inoculum helps in production of
healthy seed. In the production of certified seed, a particular distance between plots
is mandatory.
III. Inspection of Seed Plots:
Periodical inspection of the crop being raised for seed or orchards producing
grafts and seedlings of fruit trees for distribution is an important step. Eradication
of diseased plants or plant organs immediately follows the inspection. If the crop is
badly diseased the plot is rejected for seed. The procedure is followed in
production of seed tubers of potato.
IV. Drying and Aging of Seed:
Some pathogens do not tolerate drying of seeds. Viability of some seed is
longer than the pathogen present in them. Thus prolonged storage often eliminates
the pathogen from the seed. Fusarium solani f.sp. cucurbitae, infecting different
cucurbits, is internally seed-borne.
When the infected seed is stored for two years before sowing the fungus is
killed. In such method proper conditions for storage must be maintained to avoid
harm to the seed.

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V. Cleaning of Seed:
Sclerotia and oospores of many fungal pathogens and cockles or cysts of
nematodes may be present in the debris mixed with the seed. Common examples
are white blisters of crucifers, cyst nematode of sugar beet, and ear cockles of
wheat.
Cleaning of seed is done by hot air blast that removes the dust also and by hand.
In hand cleaning the seed is submerged in a 20% common salt solution. The debris
and nematode cysts or cockles float on the surface and can be skimmed off by
hand.
VI. Thermal and Chemical Treatment of Seed:
Heat or chemical treatment of seed before storage is a part of cultural practices
for healthy seed production. Chemical seed treatment is a compulsory step in the
production of certified seed. Thermal treatment of seed is favored in those cases
where the pathogen is deep seated and ordinary protective fungicides control reach
the pathogen.
Many systemic fungicides are capable of reaching the internal tissues.
Treatment of seeds with vitavax and thiram are the examples of seed treatment for
eradication of the pathogen. Bare root dip treatment of seedlings with nematicides
is practiced to control root knot and other nematodes, anthracnose of chillies,
French bean, cowpea, Indian bean, cluster bean.
VII. Site and Treatment of Nursery Beds:
Diseases like club root of cabbage, root knot of tomato are generally carried by
seedlings or grafts from the contaminated nurseries. The nursery site should be
chosen with care avoiding locations near infested fields and the soil should be
periodically treated with heat or chemical.
Soil solarization is feasible method for nursery soil treatment. The other method
is to burn a heap of farm trash over the beds. Soil fungicides are also available for
chemical treatment.
VIII. Adjustment of Harvesting Time of the Crop:
Time of harvesting affects cleanliness of the seed. Delayed harvesting of grain
crops in temperate regions gives the pathogens more time for contaminated the
seed. Grain crops harvested in wet weather often produce contaminated seed.
Harvesting of potato when the leaves are still green allows the late blight
pathogen to contaminate tubers which carry it to the next season. Such situation
can be avoided by suitable alteration in the timing of harvest of the crop.

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(3) Physical Methods:
Different physical methods employed for reduction or elimination of primary
inoculum are as follows:
I. Hot Water Treatment of Seeds and other Parts:
Hot water treatment or hot water therapy was first employed by gardeners in
Scotland for treating the bulbs of ornamental plants.
Hot water is widely used for control of seed borne pathogens especially bacteria
and viruses also fungi. Temperature and period of treatment will vary with the
infection or pathogen concerned. In hot water treatment seeds are to be presoaked for
four hours at 20-30°C, during which period dormant mycelium develops activity and
becomes more vulnerable to exposure in hot water at 50-52°C for a few minutes. e.g.
Black rot of cauliflower, Black leg of cabbage.
Seeds after treatment are to be dried very carefully before they can be use for
sowing. This method is cumbersome. Small quantities can be treated at a time.
Besides, temperature has to be exactly maintained during the period of treatment.
II. Hot Air Treatment:
Hot air treatment is less injurious to seeds and easy to operate but also less
effective than hot water. It is use for treating sugarcane stalk on commercial scale for
control Ratoon-stunting Disease (RSD). In this method hot air treatment at 54°C for 8
hour effectively eliminate pathogen without impairing germination of buds. Similarly
grassy shoot disease of sugarcane has been controlled by hot air at 54°C for 8 hour.
III. Solar Heat Treatment:
Solar heat treatment is effective in controlling both seed borne and soil borne
diseases.
Solar heat treatment controls effectively the loose smut of wheat (Ustilago nuda
tritici). In this method the seed is soaked in water for four hours (8 a.m. to 12 noon)
on a bright summer day. After this presoak, that seed is dried in the sun for four hours
from 12 noon to 4 p.m.
Ascochyta rabiei the casual organism of Ascochytosis of chick pea survives in
seed. Chaube and Singh studied the effect of sun drying on the survival of the
pathogen in chickpea seeds.
The seeds were exposed to bright sun light during the last week of May and the
first week of June. The seeds were spread on cemented floor from 8 a.m. to 4 p.m.,
daily for 15 days. Direct exposure of seeds on cemented floor reduced the recovers of
the fungus.
In seeds covered with polythene sheets on cemented floor the reduction in survival
of A. rabiei was of higher magnitude. In both the exposure methods, there was no
effect on germination of the seed.

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(4) Chemical Methods:
➢ Seed Treatment by Chemicals:
It is a known fact that large number of disease/seed borne pathogen
carried/introduced through the seeds. Seed treatment is a process of application
of chemical or protectants (with fungicidal, bactericidal, nematicidal
insecticidal properties) to seed, that prevent the carriage of diseases and also
insects causing pathogens in/on the seeds. Seed treatment also enables the seed
to overcome seedling infection by soil borne fungi.
➢ The seed treatment has two purposes:
1. Control of disease caused by seed borne pathogen/seed infection.
2. Protection of germinating seed or seedling from the attack of soil borne
pathogen.
Appropriate treatment of seeds can get rid of the seed borne pathogen and can
control, to a large extent diseases that would otherwise/harmful result. Besides,
incorporation of protective chemical on the surface of seed can reduce the change
of infection, consequently harmful effect of many soils borne pathogen which are
capable of causing decay of seeds, pre- or post-emergence of damping off or
infection in seedlings.
➢ Methods of Seed Treatment and Equipment to be used:
(i) Wet treatment:
Water soluble chemical are dissolved in water in containers of convenient
size and seed are dipped for a certain period of time and then dried properly
packing, storage, or sowing. If the seed is not properly dried, it is likely to be
damaged during storage. Metallic containers should not be used when mercurial
chemical are chosen for seed treatment. This method is generally not preferred as
its time consuming.
(ii) Dust treatment:
Dry seed treatment is usually carried out in rotary or gravity- fed seed dressers.
Bulk of seed is treated by dust formulation which does not require very
complicated equipment. Industry made are used for seed treatment which reduce
the inhalation hazards these drums treat the quickly and uniformly.
The closed barrel type rotatory drums are available in market and these are also
available in Government agencies them on loan or hire.

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(iii) Slurry treatment:
The slurry method of seed treatment eliminates, both wet and dry seed
treatment difficulties. This method is most suitable for applying wet-table powder
formulation. The chemicals are mixed with a small quantity of water and then the
mixture is applied with seeds by manual or by automatic, semi-automatic
machines.
During the process of treatment slurry gets deposited on the surface of seeds in
the form of a thin paste which dries up. This method also suitable, seed treatment
for large scale. Seeds treated with dry dusts may be stored for a long period so also
slurry treated seeds. But seeds treated by steeping in liquid cannot be stored.
➢ Type of Seed Treatment:
1. Seed disinfestation:
Seed disinfestation refers to the destruction of surface borne micro-organism
that have contaminated the seed surface but not infected seed surface. In other
words, chemical applied prior to microorganism infection.
2. Seed disinfection:
Seed disinfection refers to the eradication of micro-organism spores that have
become established with in seed coat, or in more seated tissue. In other words,
chemical applied after microorganism has caused infection.
3. Seed protectant:
Seeds and young seedling can be protection from microorganism in soil which
can caused decay of seed or seedling. That type used chemical called seed
protectants.
4. Protection:
Seed treatment includes surface treatment with pesticide, fungicide, or
insecticide.
➢ Chemicals which may be used as Seed Treatment:
Disinfection of seeds by chemicals was in vogue for a long time. Copper
sulphate used for the seed treatment of cereal seed with spores of bunt fungi.
Sulphur dust used for the seed treatment of smuts causing fungi.
With the discovery that mercuric chloride can get rid of seed borne infection in
the case of fusarium causing fungi, and later the introduction of organomercuric
compound for disinfection of seeds a new chapter opened in seed treatment in case
of fungal infection.

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Organomercuric chemicals have shown effectiveness against a number of
diseases in a number of different crops and may be called broad spectrum seed
treating fungicides. Seed dressing with organomercurial, it has been to control a
large number of diseases of cereals and commercial crops. Later on non-mercurial
organic chemicals also appeared in the market and were successfully used for seed
treatment.
Such treatments besides controlling infestation and or infection, as the case may
be, also afford protection to the seeds or during germination and young seedling in
the early stage of growth from soil borne fungi.
➢ The introduction of systemic fungicides for seed treatment has
added further possibility:
(a) Control of pathogen located deep inside the seeds.
(b) Control of air borne infection at a later stage of growth of the crops because its
systemically translocated to aerial part.
➢ Precaution of Seed Treatment:
1. Many chemicals used for the treatment of seeds are poisonous or toxic to man
and animals, so they should be used with caution.
2. Chemically treated seeds should never be used for consumption by man and
animals as food and feed.
3. Seed treatment should be carried out in well aerated area.
4. Contract with chemicals through breathing avoided and also avoided skin and
eye.
(5) Biological Methods:
Bacterial and fungal antagonists may be more effective when applied to seed
than applied to soil because of their proximity, in large numbers, to the infection
court. Seeds are vulnerable to seed borne and soil borne pathogens, and the period
of protection not be long.
The first commercial use of an organism to control a plant disease in soil is
Agrobacterium radiobacter to control crown gall in rosaceous hosts. Kerr (1980)
isolated strain 84 that was antagonist to A. tumefaciens strain 84 produces an
antibiotics called “agrocin 84,” which is one of a group of highly specific
antibiotic known as nucleotide bacteriocins.

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Since 1973, Agriculture Research Institute has supplied commercial growers
with culture of strain 84, but now the organism is marketed commercially in India.
Seeds, cuttings, or roots of young plants are dipped into a bacterial suspension; in
order for the non-pathogenic strain to be effective, the ratio of pathogenic to non-
pathogenic at the root surface cannot exceed one.
Seed treatment with strain 84 is inexpensive, simple, and effective. It is
harmless to humans and other mammals; inoculum can be stored in peat and retain
a half-life of six months at room temperature, in field tests, B. subtilise was
effective when soil was moist.
Table 1. Selected Examples of Root Diseases Control By Application of
Antagonstic Bacteria or Fungi to seeds

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Procedure for Healthy Seed Production
❖ Characteristics of Good Quality Seeds :
1. It must be genetically pure.
2. It should have the required level of physical purity for certification.
3. It should have high pure seed percentage.
4. It should be free from other crop seeds.
5. It should be free from objectionable weed seeds.
6. It should be free from designated diseases.
7. It should have good shape, size, colour, etc., according to specification of
variety.
8. It should have high physical soundness and weight.
9. It should posses high physiological vigour and stamina.
10. It should posses high longevity and shelf life.
11. It should have optimum moisture content for storage.
12. It should have high market value.
❖Seed Production Starting with Seed Nurseries :
1) Source of Seed :
The seed enterprise through research recommends the variety and the class of
seed to be multiplied. Seed must be obtained from an authentic source. The
contracting seed enterprise will supply the registered seed grower with higher class
seed than the class the farmer has been contracted to grow.
2) Selection of Land :
The land/field must meet seed production requirements. For certification
purposes, field/land requirements of the enterprise must meet the selection
requirements of the SQCU. The land must be ecologically suitable.
The choice of the right nursery site is a prerequisite for proper seedling
establishment, reduction in seedling damage and stuck during transplanting.
The land selected for seed production must be fertile, preferably light textured,
with adequate irrigation and proper drainage system. The field should be free from
weeds and volunteer plants from the previous paddy crop. The field should not be
infested with serious pests and diseases.

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3) Isolation/ Previous Cropping :
The field should be well isolated in accordance with rice seed isolation and
previous cropping requirements. Generally as a self pollinating crop isolation is
normally not very serious except for inadvertent admixtures. A minimum of about
10meters from another rice field is acceptable. Rice seed should follow a rice crop,
only after a minimum of 2years duration.
4) Land Preparation :
There are different ecologies for rice seed cultivation in Sierra Leone. Rice
varieties are ecology-specific, and yield best in a specific ecological condition. The
nursery area must be properly brushed, and all thrash removed. The area is then
ploughed and the beds are raised.
Land preparation must be thorough, to attain the required tilth, to suppress weed
growth and enhance moisture retention, easy germination and root penetration.
Remember, good land preparation is the starting point for good weed control.
5) Nursery Bed Preparation and Sowing :
Due to the high cost of breeder/foundation seed, it is essential to raise the
nursery bed in a well managed field, if healthy and robust seedlings are to be
obtained. Optimum seed rate should be applied usually at 40kg/ha and every seed
must be utilized by adopting good nursery management practices. A sparse well-
managed nursery gives healthy seedlings for the main field.
6) Fertilizer Application :
Apply basic fertilizer preferably NPK, 15:15:15 which is the recommended
NPK fertilizer before nursing/planting.
For nursing purposes, puddle the soil if the field has been used for another rice
variety to avoid introduction of volunteer crops which is a source of mixing the
variety under seed production; in other words check previous cropping state, to
avoid inadvertent admixtures. Dry the seed for 2-3 days to break dormancy and
then pre-germinate to be able to determine percentage germination before nursing.
After nursing the seed, water the nursery adequately to ensure seeds imbibe enough
water to trigger physiological processes to speed up germination. Apply ammonia
after germination to speed up growth and root penetration.
7) Labeling :
Label all nurseries clearly for easy identification; each label should have the
necessary information, such as crop spp, variety, class of seed, date nursed etc.
This stage also advertises your new variety of rice seed.

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8) Transplanting :
During transplanting, adhere to field inspection regulations of isolation
distances and previous cropping requirements. If transplanting is to be done on old
irrigated fields, the fields must be properly pulverized to effectively destroy weeds
and any volunteer plants. Flood the field for about twenty four hours. Drain field
for about a day before transplanting the seedlings. This allows seedlings to be
firmly established before field is flooded again.
Transplanting is done when the nursery crop is about 25-30 days old. When
seedlings are transplanted at a very young stage there is a delay in flowering.
Equally, when the seedlings are transplanted at a very old stage, there is
accelerated flowering. In both cases the tillering capacity of the crop is reduced.
Therefore transplant at optimum time of 25-30 days after nursing.
Before transplanting, the seed plot should be properly pulverized and evenly
leveled so as to allow even water distribution and to keep fertilizers applied within
the seed plot.
Uproot seedling by using a spade or cutlass. Remove seedlings gently with a
ball of earth around the roots. Transplant with the ball of earth at least 1 to3
seedlings per hill with a spacing of 20cm by 15cm. This will reduce shock and
allow easy seedling establishment in the seed plot. Tiller formation is enhanced
when seedlings are transplanted at the rate of 2-3 seedlings per hill/stand to
enhance good tiller formation.
Where there is ample evidence of presence of iron toxicity, construct drainages
to drain water before transplanting.
9) Weed Control :
Two types of weed control measures are available: Manual weeding 2-3 times
depending on weed situation and or use of chemical weed control/herbicide.
Choice depends on farmer and resources. Two types of chemical control measures
are available; post emergence and pre-emergence. At pre-emergence herbicide is
applied before or immediately after planting. For post emergence the herbicide is
applied after the crop/weeds have germinated.
• For hand weeding, two weeding are recommended.
First weeding to be carried out when crop is 14-21 days old.
Second weeding is carried out when crop is 35-42 days old.

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10) Water Control :
Rice is a water loving crop and does well when water is available through its
growth cycle. Effective water control engenders high yields. It is useful to erect
peripheral bunds around rice plots, to control water by facilitating regular drainage
and impounding of water. Poor water control resulting in long water impairs early
tiller formation, though encourages late tiller formation and increased number per
hill.
11) Field Inspection :
Field inspection is critically important in seed production. It provides the best
opportunity to observe and measure the quality of plants which produce the seed.
This is done by observing the parent plants in the field. Seed fields are inspected to
ensure that the seed fields are genetically, physically and pathologically pure
within the limits of field quality standards required by law or established by the
production program.
❖Other Factors Influencing Seed Production :
During seed multiplication, certain guidelines should be followed - otherwise
the quality of the seeds will be affected.
1) Site / Land Selection :
The soil in the seed production field should be fertile with adequate irrigation
and good drainage facilities. The field should be devoid of high weed incidence
and free from volunteer plants (Volunteer plants are the unwanted plants growing
in the seed production field from the previous seasons’ crop). The field should not
be cultivated with the same crop variety in the previous season. It should have
enough sunlight and proper aeration for the effective control of pest and diseases.

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2) Selection of Species and Seed Source :
While selecting the seed variety, care should be taken to select the varieties
preferred by the farmers in a particular area. Healthy and uniform sized seeds from a
reliable source should be selected. Seeds should be selected based on the type of seed
production i.e. breeder seeds are required for the production of foundation seeds;
foundation seeds are required for the production of certified seeds. Selected seeds
should be genetically pure with high germination percentage and vigour.
3) Field Preparation :
Soil condition in the selected field should be suitable for the crop. The field should
be ploughed thoroughly without any lumps. Green manure crops can be raised in the
field in order to enhance the nutrient content of the soil. Organic manures like farm
yard manure, compost and vermicompost can be used to enhance the soil fertility.
Field should be irrigated well within three days of sowing to avoid hardness of the
soil.
4) Seed Selection :
Salt solution can be used to remove the chaffy seeds from good seeds. Take some
water in a vessel and drop an egg in it. Keep adding salt to it slowly until the egg
reaches the surface of the water. When the seeds are dropped in this water, the good
quality seeds will sink into the water. Remove the unviable seeds that float on the
surface of the water. Wash the selected seeds in good water for 2 - 3 times to remove
the salt deposits. If this is not done, the germination capacity of the seeds will be
affected. By this method, the unviable seeds can be removed completely. This method
should be followed when there is more of chaff.
5) Seed Testing :
The selected seeds should be tested for its viability, i.e. seed germination. Seed
production and multiplication is possible only when the germination capacity is high.
If the germination rate is high ultimately the seed multiplication can also be higher.
6) Seed Germination :
Germination capacity of a seed lot refers to the capacity of the seeds in that lot to
germinate normally and produce all parts of a healthy seedling and grow. The
necessary parts of the seedling include well developed primary roots, young pair of
leaves and one or two cotyledons.
% of Germination = Number of normal seedlings x 100
Total number of seeds germinated
A germination rate of 70-80% is an indication of high seed viability. Germination
can also be affected by seed dormancy.

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7) Seed Vigour :
Seeds with good vigour will produce good quality seedlings that will grow and
give good yields. Seed vigour is the sum total of all the seed attributes that favours
rapid and uniform standard establishment in the field under varying field
conditions. In general, seeds with good germination capacity and uniformity in size
will have good vigour. It varies from species to species.
Weak seeds will have poor germination and die under the field conditions; if
they survive they would not yield healthy seedlings. Hence, it is necessary to test
the germination of the seeds before sowing in the main field. A countable number
of seeds can be sown in small pots filled with moistened soil and placed in a sunny
area.
After a few days, number of normal seedlings in each pot should be counted.
8) Seed Dormancy :
Seed dormancy is the temporary suspension of growth of viable seeds
accompanied by reduced internal metabolic activity. It is the resting stage of the
seed and it delays germination of the seed. Unfavourable climatic conditions like
temperature, variation and lack of water leads to seed dormancy. Dormancy may
occur due to the presence of a hard seed coat, immature embryo and also due to the
presence of germination inhibitors in the seeds. It may also be due to the exposure
of seeds to excess heat, light or darkness and also due to the presence of chemical
toxins in the seeds.
Dormancy of the seeds can be broken by any of the following methods,
i. Scarification – Removal of the hard seed coat by rubbing the seeds with sand
paper. Eg. Pulses
ii. Hot water treatment – Soak the seeds in hot water at 45-50°C. Eg. Tree crops.
iii. Leaching – Soak the seeds in water for overnight to remove the germination
inhibiting chemicals present in the seeds. Eg. Coriander.
iv. Stratification – Subject the seeds to very low temperature of 0-5°C to break the
embryo dormancy. Eg. Cole crops.
v. Light treatment – Some seeds do not germinate in dark and periodic exposure
to light is essential to break the dormancy. Eg. Lettuce.
9) Sowing Season :
The best sowing season depends upon the suitable temperature, rain, wind
speed and photoperiod. For quality seed production there should not be heavy rains
during the flowering stage of the seed crop and the maturity of the seed should
coincide with the summer season. Seeds harvested during dry season are always
better in quality.

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10) Planting Density :
Density of the plant in the field directly influences the quality of the seeds.
More densely populated planting leads to the incidence of diseases, whereas less
populated planting acquires more weed infestation with uneven ripening. Hence it
is necessary to maintain the optimum plant density pertaining to each crop variety.
11) Weed Management :
Land selected for seed production should be maintained free from weeds. Weed
seeds will remain dormant for a long period and grow faster than the main crop and
produce seeds, which will reduce the purity of the seed crop. Removal of weeds at
all stages in the seed production field is essential for maintaining the purity of the
seeds.
12) Pest and Disease Management :
Insects will spread disease causing microbes and particularly affect the seeds.
Special care and attention should be given at every stage of the seed production in
order to keep the field free from the pest and diseases.
13) Intercultural Technologies :
The soil in between and around the crop should be tilted slightly for good
aeration and better water holding capacity. Soil should be heaped or mounted near
the root region of the plant. This will enhance the water and nutrient absorption
capacity of the plant and also help the plant to stand upright. The fruits or grains in
the plant will be free from soil borne pathogens.

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14) Isolation Distance :
It is the distance maintained between the seed crops and the different varieties
of the same crop located in the adjacent area in order to maintain the genetic purity
of the seeds. Isolation distance is based on the pollination behaviour, pollinating
agent, flying capacity of the pollen, stages of seed crop and nature of variety or
hybrid. Maintaining appropriate isolation distance avoids cross pollination and
crossing of genes. Two types of isolation are followed – space isolation (planting
distance) and time isolation (difference in the time of sowing).
15) Bagging Technique :
In order to protect the pollination through insects or wind covering the floral
portion of a plant is practiced. Materials like mosquito net, paper bags, and nylon
stockings are used for bagging purpose. The base of the bag is tightly secured
around the stem with a cotton ball in it. This mechanical isolation method is
suitable for small quantity of seeds. Eg. Tomato.
16) Rouging :
In the seed production technology rouging is an important technique to be
followed from field to storage. It is the process of removing the plant varieties of
other than the variety grown for seed production like other crops, weeds etc.
Rouging should not be done in intense sun light. Off-types should be removed
before their flowering stage. Off-types should also be removed after harvest,
during drying, processing and storage. Timely rouging is critical for the
conservation of the genetic purity of the seeds.
Crops Isolation Distance (m)
Self Pollinated Crops
Paddy 3
Wheat 3
Groundnut 3
Ragi 3
Blackgram & Greengram 10
Cross Pollinated Crops
Maize 400
Pearlmillet Hybrid 1000
Sunflower 400
Often Cross Pollinated Crops
Redgram 200
Sesame 100

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17) Harvest of the Seed Crop :
Harvest can be done only when the seeds attain complete physiological maturity
(full size and maturity). Harvest should coincide with the dry season. It will
increase the germination capacity of the seeds. Method of harvest and harvest time
varies from crop to crop. Most preferred method of seed harvesting is manual
harvesting. It will reduce the mechanical damage to the seeds. The total number of
harvest of matured seeds varies from crop to crop.
E.g. Single harvest crops- Paddy and Maize, Multiple harvest crops- Tomato,
Brinjal, Okra etc.