Seed sampling, seed lot, types of samples, principles and procedures of seed sampling, sampling intensity, types of sampling devices, types of seed divider

1. SEED SAMPLING
PRINCIPLES & PROCEDURES
Prof. Kumari Rajani
Department of Seed Science & Technology
Bihar Agricultural University
Sabour, Bhagalpur-813210

2.  Sampling
A process of obtaining sample from the seed lot by taking small
portions at random from different position of the lot and combining
them
 Seed Lot
It is specified quantity of seed, physically identifiable, in respect of
which a seed test certificate can be issued
 Lot Number
Set of numbers, letters, symbols or their combination that singly or
combined uniquely identifies the lot
 Primary Sample
Small portion taken from one point in the lot
 Composite Sample
It is formed by combining and mixing all primary samples taken from
the lot
TERMINOLOGIES

3.  Submitted sample
Sample submitted to seed testing laboratory. The size of the
submitted sample is specified in the Seed Testing Rules
 Sub-sample
Portion of the sample obtained by reducing the sample using
prescribed methods
 Working Sample
Sub-sample taken in the laboratory from the submitted sample, on
which one of quality test is made
 Homogeneous Lot
A seed lot that is of adequately uniform composition in its entirety
 Heterogeneous Lot
A seed lot that is not of adequately uniform composition in its
entirety
 Label
All tags or other devices attached to or written, stamped or printed
on any container or accompanying any lot of seed in bulk stating all
required seed lot information

4.  To obtain a representative sample (from a seed lot) of a size
suitable for tests, in which the probability of a constituent being
present is determined only by its level of occurrence in the seed lot
 The size of the submitted sample required for testing is small as
compared to the size of the lot, therefore, care must be taken to
ensure that the submitted sample represents the lot of the seed to
be tested.
 It is observed in many cases that the variations in test results are
due to the variation in the sampling. Hence seed sampling is one of
the basic components responsible for the accurate Seed Testing
results.
 When the sample originates from seed lot, it is expected that the
results reflect the average quality of the seed lot
OBJECTIVE OF SAMPLING

6. SAMPLING SCHEME

7. HETEROGENEITY IN A SEED LOT
 Differences in seed weight, shape and flowing properties
between the constituents (seeds, impurities) can cause
separation->heterogeneity in a seed lot.
 In case of obvious evidence of heterogeneity, sampling has to be
refused.
 In cases of doubt, a heterogeneity test can be made.

8. General Principles & procedures of Sampling
The seed sampler needs to ensure that the minimum amount of
seed required for the requested test(s) is sent to the testing
laboratory and enough seed remains available for obtaining
duplicate samples if requested.
Primary samples of approximately equal size must be taken from
a seed lot.
When the seed lot is in containers, the containers to be sampled
must be selected at random or according to a systematic plan
throughout the seed lot.
Primary samples must be drawn from the top, middle and bottom
of containers, but not necessarily from more than one position in
any container.

9. When the seed is in bulk or in large containers, the primary
samples must be drawn from random positions.
Containers must be opened or pierced for abstraction of primary
samples. The sampled containers must then be closed or the
contents transferred to new containers.
When seed is to be packed in special types of containers, it
should be sampled, if possible, either before or during the filling
of the containers.
Sampling seed lots of seed tapes and seed mats should be done
by taking packets or pieces of tape or mat.
The instruments being used must neither damage the seed nor
select according to seed size, shape, density, chaffiness or any
other quality trait.

10.  Seed lot shall be so arranged that each individual container or
part of the lot is conveniently accessible
 A large sample is more representative of a lot than is a small
sample
 The sampler should determine that all seed bags sampled are
identified as belonging to a single lot, either by a label or mark
on the bag
 The sampler must sample the minimum requisite number of
bags from the seed lot
 Seed may be sampled in containers or when it enters
containers. The containers must be fit for purpose, i.e. must not
damage the seed, and must be clean to avoid cross
contamination
Cont…

11.  Primary samples should be taken from random positions and
depths
 If primary samples appear uniform, they shall be combined to
form the composite sample
 Composite sample should be thoroughly mixed
 If the composite sample is of appropriate size it may be regarded
as the submitted sample without reduction
 Seeds treated with poisonous fungicide should be identified so
that the sampler could take precautions during sampling
Cont…

12.  Following information should be checked on label
I. Kind
II. Variety
III. Lot Number
IV.Date of Test
V. Seller's name & address
 In case of certified lots sampler should check Information on
seed certification tag
 Name & Address of certification agency
 Kind & Variety
 Lot No.
 Name & address of certified seed producer
 Date of issue of the certificate & its validity
 Class & Designation of seed
 Period during which the seed shall be used for sowing
Cont…

15.  Under seed law enforcement programme only trained and
experienced officials are authorize to undertake sampling and
he has to:
 Give notice to such intention to the person from whom he
intends to take sample
 Take three representative samples in the prescribed manner and
mark & seal
 One sample to be deliver to the person from whom it has been
taken
 Second to be sent for analysis to the Seed Analyst of the area
 Third to be retained for any legal proceedings
 At least two persons should be present and obtain the signature
of both the witnesses on Form VII of the Seed Act

16.  On request of the sampler, the owner shall provide full
information regarding bulking and mixing of the lot
 If the nature of the presentation of the seed lot or container
makes it impossible to adequately apply these procedures, then
the sampling Shall not be undertaken, and alternative
presentation of the seed lot should be sought
 The size of the seed lot should not exceed to the maximum size
as prescribed in the rules subject to 5 % of tolerance
SIZE OF LOT
Seed size Maximum quantity per lot
Larger than wheat and paddy 20,000 kg
Smaller than wheat and paddy 10,000 kg
Maize 40,000 kg

17. SAMPLING INTENSITY
 It refers to the minimum number of bags or containers of seed
that should be sampled from a specific seed lot
 It is based on size of the seed lot
 When sampling seed lots in bulk, in containers of different or
very small sizes, the Following sampling intensity is regarded as
the minimum requirements
Lot size No. of Primary Samples to be taken
Less than 50 kg 3
50-500 kg 5
501-3,000 kg 1 primary sample for each 300 kg, but not less than 5
primary samples
3,001-20,000 kg 1 primary sample for each 500 kg, but not less than 10
primary samples
20,001 and above 1 primary sample for each 700 kg, but not less
than 40 primary samples

18. For small containers (tins, cartons, or packets 'as used in the retail
trade):
A 100 kg weight of seed is taken as the basic unit and the containers
are combined to form sampling units not exceeding this weight
SN Containers No. of Primary Samples
1. 1-4 3 samples from each container
2. 5-8 2 samples from each container
3. 9-15 1 samples from each container
4. 16-30 15 samples in total from the seed lot
5. 31-59 20 samples in total from the seed lot
6. 60 or more 30 samples in total from the seed lot
For seed lots in bags or containers that are of uniform size and are
15 kg to 100 kg capacity, the following is the minimum requirement:

19.  For seed lots in containers smaller than 15 kg capacity,
containers shall be combined into sampling units not exceeding
100 kg
Ex: 20 containers of 5 kg, 33 containers of 3 kg or 100 containers
of 1 kg
 For sampling purposes, each unit is regarded as one container
and the sampling intensity prescribes for big containers will
apply
 For seed mats and tapes, small packets or reels may be
combined to sampling units of not exceeding 2000000 seeds

20. PROCEDURE FOR SAMPLING
Taking Primary Samples
 The primary samples are drawn with the aid of suitable seed
triers/or by hand in case of chaffy/non free-flowing seeds
 The sampler needs to ensure that the minimum amount of seed
required for the requested test (s) is sent to the seed testing
laboratory
 Primary samples must be of approximately equal size regardless
of the method used
 The containers or bags to be sampled shall be selected at random
throughout the seed lot and the primary samples shall be drawn
alternatively from the top, middle and bottom

21.  In case of chaffy seeds (not free flowing), the primary samples
may be drawn by hand.
 Groundnuts, soybeans, fussy cotton, beans and similar crops
may also be drawn by hand to avoid damage to the seed
 Before taking primary samples, the seed sampler has to ensure
the requirements like marking, sealing, maximum size of lot,
homogeneity and presentation of the seed lot
 All primary samples are then thoroughly mixed to make
composite sample from which a submitted sample can be drawn

22. Method of Preparing Composite/Submitted Samples
 When the primary samples appear uniform they are combined and
thoroughly mixed to form the composite sample
 From composite sample submitted sample of requisite weight or
more is obtained either by repeated halving or by abstracting and
subsequently combining small random portions

23. Dispatch of Submitted Sample
 Each submitted sample should be sealed and marked
 The label should contain all the necessary detail such as
 Variety
 Class of seed
 Quantity in the lot
 To whom it belongs
 Name of producer
 Seed treatment
 Date of harvesting and threshing
 Sampled by
 Date of sampling
 Kind of tests required

24.  For germination tests it should be packed preferably in cloth bag
 For determination of moisture content it should be packed
separately in moisture-proof containers from which as much air as
possible has been excluded
 Samples should be despatched by the sampler to the seed testing
laboratory without delay

25. Sampling seed lots may be done by several methods:
1. Automatic sampling from a seed stream
2. Manual sampling from a seed stream
3. Sampling stick
i. Stick Trier
ii. Sleeve Type Trier
iii. Spiral Trier
4. Nobbe trier
5. Cargo sampler
6. Sampling by hand
Methods of Sampling in Seed Testing Laboratory

26. AUTOMATIC SAMPLING FROM A SEED STREAM
Seed may be sampled by automatic sampling devices, provided
that the instrument uniformly samples the cross section of the seed
stream and the material entering the instrument does not bounce
out again
It may be operated either under manual or automatic control
The intervals between taking primary samples should be
constant but may also vary randomly
MANUAL SAMPLING FROM A SEED STREAM
Seed streams may also be sampled by using manual instruments

27. SAMPLING STICK
The sampling stick (Ex: Stick trier or Sleeve type trier, Thief trier,
Nobbe trier, Spiral trier)
Consists of two parts, one of which fits loosely inside the other,
but tightly enough so that seed or impurities do not slip between
them
The outer part has a solid pointed end. Both parts have slots in
their walls so that the cavity of the inner part can be opened and
closed by moving the two parts against each other by either a
twisting or a push-pull motion
The sampling stick may be used horizontally, diagonally or
vertically
The spiral trier has slots in a spiral arrangement for their
subsequent opening from the tip to the handle and may only be used
for seeds of a size smaller than Triticum aestivum

28.  The triers are used for taking free flowing seed samples
 Bin samplers: used for drawing samples from the lots stored in the
bins
 Sleeve trier is the most commonly used trier for sampling
Stick or Sleeve Trier (Bag trier) Sampling using a sleeve trier

29. NOBBE TRIER
 This trier is a pointed tube with an oval opening near the pointed
end
 This trier is relatively compact and small, making it easy to
transport
 A Nobbe trier is suitable for sampling free-flowing seed in bags but
not in bulk or mini-bulk containers
 It may only be used horizontally. Its use is limited to penetrable
containers
 The Nobbe trier must be long enough that the opening (slot/hole)
reaches the center of the bag
 The minimum internal diameter of the Nobbe trier is about 10mm
for clovers, alfalfa and similar seeds, about 14mm for cereals and
about 20mm for corn

30. Nobbe Trier
 The trier is inserted gently into the container with the trier
opening facing downwards
 The trier is inserted into the bag upwards at an angle of about
15-30° to the horizontal until it reaches the center of the bag
 It is then rotated 180o, bringing the hole to face upwards

31.  It consists a special type of chamber that
is fixed to a shaft. The lower part of the
chamber is cone-shaped with a pointed
end
 There is a closing system in the chamber
that may be a collar on the outside of the
instrument, a wing connected to a door or
a valve with a spring
 Some cargo samplers can be closed
before they are drawn back from the
sampling position; others cannot be
closed so that the filled chamber is open
during withdrawal
CARGO SAMPLER or BULK SAMPLER

32. SAMPLING WITH TRIERS
"The tubes vary in length and
diameter and are made with or
without partitions for different
kinds of seeds
Thief Trier

33.  The choice of an appropriate trier size is predicated by size of
seed and the width of the trier slot
 An appropriate trier is that whose width of slot is twice the size of
the seed
 Small-seeded crop kinds like clovers, alfalfa, rape and others of
similar size must only be sampled using triers with a minimum
slot width of ¼”
 Medium seeded crop kinds like cereals, rice, sorghum and others
of similar size must only be sampled using triers with a minimum
slot width of ½”
 Large-seeded crop kinds like sunflower, corn, cotton including
large legumes like beans must only be sampled using triers with a
minimum slot width of ¾”
 Very chaffy grasses must only be hand sampled
CHOICE OF TRIER

34.  This method can be used for all species
 The most suitable method for seed that may be damaged by the
use of triers, chaffy and fuzzy seeds such as cotton, tomato,
grass seeds etc, seeds with wings, seeds with low moisture
content, seed tapes and seed mats
 For hand sampling seed in containers, all positions inside the
containers must be accessible
SAMPLING BY HAND
 Where it may be impossible to obtain
samples from the lower parts of bags or
bins, the seed sampler should request
that the containers be partially or
completely emptied to ensure access to
all positions of the container

35.  The open hand is inserted through the top of the bag with fingers
held tightly together, until the desired depth is reached
 The hand is then closed with fingers held tightly together to
ensure that few, if any, seed escape, and the hand slowly
withdrawn
 While removing the samples from the containers, care should be
taken to close the fingers tightly so that no seeds escape
 This process is repeated a number of times in different parts of
the lot and at different depths, until the required sample size is
obtained.

36.  The submitted/working sample must be obtained either by
repeated halving or by abstracting and subsequently combining
small random portions.
 Seed samples received in the Seed Testing Laboratory
(submitted sample) are required to be reduced to obtain
working samples for carrying out various tests.
Sample Reduction Methods Or Methods for
obtaining Working Samples

37.  This method is suitable for all kinds of seeds except some very
chaffy seeds.
 The apparatus divides a sample passed through it into two or
more approximately equal parts.
 The submitted sample can be mixed by passing it through the
divider, recombining the parts and passing the whole sample
through a second time, and similarly, a third time if necessary.
 The sample is reduced by passing the seed through repeatedly
and removing parts on each occasion.
 This process of reduction is continued until a working sample of
approximately, but not less than, the required size is obtained.
Mechanical Divider Method

38.  Consists of a hopper, cone, and
series of baffles directing the seed
into two spouts.
 About 38 channels, each about 25
mm wide for large seeds and about
44 channels, each about 8 mm wide
for small free-flowing seeds.
 They are arranged in a circle and are
directed inward and downward, the
channels leading to one spout and
the spaces to an opposite spout.
Conical Divider (Boerner Type)

39.  The seed flows downward
through a hopper onto a shallow
cup or spinner
 Upon rotation of the spinner by
an electric motor the seeds are
thrown out by centrifugal force
and fall downward
 The circle or area where the
seeds fall is equally divided into
two parts by a stationary baffle
so that approximately half the
seeds fall in one spout and half
in the other spout
Centrifugal Divider (Gamet Type)

40.  Consists of a hopper with about 18 attached channels or ducts
alternately leading to opposite sides
 A channel width of about 13 mm is suitable
Soil Divider (Riffle Type)

41. Spoon Method
 The spoon method is recommended for sample reduction for
seed health testing
 Permissible for sampling of small seeded seeds
 Pour the seeds evenly over the tray
 Remove small portion of seeds using spoon and spatula
Modified Halving Method

42.  Restricted to specific genera of chaffy seeds such as Brachiaria,
Cenchrus, Chloris, Echinochloa Gossypium (linted seed only),
Oryza, Pennisetum (non glaucum)
 Genera of easily damaged fragile seeds such as Arachis
(Groundnut), Glycine (Soybean) and Phaseolus (Bean)
Hand Halving Method
 The hand halving method can
also be used with the species
where all other dividing
methods are extremely difficult
or impossible to use

43. “Incorrect sampling may lead to misleading test results,
discarding seed lots of high quality or to the approval of seed
lots of low quality, which may reduce crop yield or even result
in complete failure”
Arne wold (1986)