Seed health testing is the process of identifying disease-causing agents in seeds to ensure their health and meet certification standards. Various methods, including visual examinations, culture methods, PCR, and ELISA, are employed to detect fungal, bacterial, and viral pathogens in seeds. This testing is crucial for promoting healthy crop establishment and enhancing agricultural productivity by preventing the spread of diseases.

1. SEED HEALTH TEST

2. • Seed Health Testing is a Science of determining the
presence or absence of disease causing agents.
• To determine the health status of a seed sample,
and by inference seed lots
SEED HEALTH TEST

3. • To determine the health status of a seed lot which in turn
establishes the sanitary condition of the seed in commerce.
• To obtain objective proof of whether the seed lot meets the
requisite certification standards or not.
OBJECTIVE

4. METHODS OF SEED HEALTH TESTING FOR
FUNGI
• Visual examination- with or without
stereomicroscope.
• Inspected in dry state for the presence
of impurities such as ergots or other
sclerotia.

5. • Infected seeds have a characteristic
black powdery mass generally along
the suture.
• Severe infection - most of the
endosperm together with pericarp
and aleurone layer gets destroyed
giving a boat like appearance.
DETERMINATION OF KARNALBUNT (Neovassia Indica)
OF WHEAT

6. • Seeds are opened with the
help of the blade
• Whole grains transformed
into black powdery mass
DETERMINATION OF BUNT (Neovassia horida) OF
RICE

7. BLOTTER METHOD
• Seeds are placed on
moistened blotters, filter
papers atleast 20mm apart.
• Blotters are placed in closed
containers and incubated for 7
to 10days and later examined
for pathogens.

8. WASH METHOD
• Seeds are immersed in water with
a wetting agent and shaked
vigorously to remove fungal
spores, hyphae etc.
• Excess liquid is removed and
material is examined.

9. UV Examination
• Toxins in Fungi gives Fluoroscence
in appearance This represents
presence of Fungi exposed to UV.

10. • Soak seeds for 24hours at 20°C in Sodium
hydroxide and Trypan Blue.
• Separate the embryos by passing the soaked
material along with warm water (50-60°C).
• Use mesh sieve for separation of embryo
• Embryos are washed in wire basket and
dehydrated in 95% alcohol for 2min and later
transferred to a mixture of lactophenol and
water.
NaOH SOAKING METHOD

11. EMBRYO
COUNT
METHOD

12. METHODS TO DETECT SEED BORNE BACTERIAL
PATHOGENS
• Various methods have been developed.
• Some of the methods are simple and some are
specialized namely serological methods.

13. CULTURE METHOD
• By culturing the samples on the particular media.
• Presence of bacteria can be observed on the
media.

14. AGAR PLATE METHOD
•After pretreatment seeds are on the
surface of 2% malt extract sterilised
agar.
•After plating dishes are incubated at
20-25°C for 5-8 days.

15. GROWING OUT TEST
• The 'growing out' bioassay of a working seed sample
involves the sowing of test seeds into seedlings under
conditions optimal for the disease development in
glass house or closed environmental chambers.
'Growing out' test has been successfully used for a
large number of Xanthomonads and pseudomonad's.

16. • Seeds to be tested are soaked in tapwater.
• Seed or part (embryo) of it is triturated
• Triturate is transferred to a well cut in a diffusion media(agar
gel).
• Antiserum specific for a suspect virus in a seed is placed in
separate well.
DOUBLE DIFFUSION TEST
• In time the virus particles(antigen) and antibody
molecules diffuse towards one another.
• Since diffusion is in two direction it is called Double
diffusion
• The preciptate appears as a white band.

18. LATEX FLOW METHOD

19. PCR METHOD
• It is a kind of molecular method.
• Specific primers are used in this method.
• PCR is a promising tool for distinguishing specific sequences
from a complex mixture of DNA and therefore it is useful for
determining the presence and quantity of pathogenspecific or
other unique sequences within a sample

21. • In this procedure, antiserum specific for a given virus is used
to coat the polystyrene plate.
• Antibody molecules become absorbed.
• Then seed sample is added to the plate.
• It is followed by adding enzyme labelled specific antibody to
the plate.
ELISA TEST
• The enzyme alkaline phosphates is conjugated to the antibody
molecules specific for the virus under examination.
• Finally enzyme substrate is added to the plate.
• Hydrolyzed substrate is determined by measuring the
extinction spectrophotometrically or by visual observation.

23. RADIAL DIFFUSION
• Procedure consists of charging the wells with the seed or
seedling preparations being tested for the presence of
virus.
• When virus molecules are present, they diffuse radially
from the well surface.
• A ring or halo results around the charged well.

24. LOOP MODIFIED
ISOTHERMAL
AMPLIFICATION

25. CONCLUSION
• Seed health testing is a crucial process for detecting pathogens in seeds, helping
to prevent the spread of diseases that can significantly reduce crop yields.
• By identifying bacterial, fungal, or viral contaminants early, seed health tests
ensure that only healthy seeds are used for planting, promoting better crop
establishment and minimizing the need for chemical treatments.
• This ultimately leads to improved agricultural productivity and more sustainable
farming practices.

26. 1. What is the primary objective of seed health testing?
A) To evaluate seed germination B) To detect seed-borne pathogens
C) To determine seed moisture content. D) To assess seed vigor
2. Which of the following is a seed-borne
pathogen?
A) Xanthomonas citri B) Fusarium oxysporum
C) Both A and B D) Neither A nor B
3. What is the principle of PCR (Polymerase Chain Reaction) test?
A) Amplifies DNA sequence B) Detects antibodies
C) Evaluates seed germination D) Determines seed moisture
content

27. 4. What is the purpose of the ELISA (Enzyme-Linked Immunosorbent Assay)
test?
A) Detects antibodies B) Evaluates seed germination
C) Determines seed moisture content D) Assesses seed purity
5.How are the results of the Double Diffusion Test interpreted?
*
A) Presence of precipitate indicates positive result
B) Absence of precipitate indicates positive result
C) Size of precipitate indicates positive result
D) Color of precipitate indicates positive result
6.NaOH SOAKING method principle
a)presence of precipitation b) absence of precipitation
c)contrast colour between diseased. d) formation of aggregates
and hea,lthy seed

28. 7. Which test detects seed-borne
bacteria?
A) Agar Plate Test B) Blotter Test
C) Grow-out Test D) PCR Test
8. What is the Blotter Test used for?
A) Detecting fungal pathogens. B) Detecting bacterial pathogens
C) Evaluating seed germination D) Determining seed moisture
content
9.Incubation period for blotter paper
method
A)3days B)7 -10 days
C)1 -2month D)2-3 hours
10.LAMP is used to detect
A)fungi B)virus
c) bacteria D)algea

29. Thank you