This document discusses seed lot sampling techniques. It defines a seed lot and explains that representative sampling is important to obtain accurate test results. There are different types of samples including service samples sent by individuals, official samples taken by inspectors, and certified samples taken by certification agencies using a four step process. Primary samples are drawn from different parts of a seed lot and combined into a composite sample, which is then reduced to a submitted sample for testing. Sampling intensity depends on the size of the seed lot, ranging from sampling each container for small lots to one sample every 700kg for very large lots. Common sampling methods and equipment are also described.

1. SEED LOT & ITS SAMPLING TECHNIQUES
Shreya Sen
Birsa Agricultural University, Ranchi – 834006
1 Dept. of Genetics & Plant Breeding
Corresponding Author email: ssen743@gmail.com Contact : 6200871142
Introduction
Seed testing is being conducted to assess the quality of seed before it is sown. For carrying various quality
tests, a representative seed sample is drawn from seed lot, in which the same constituents are present as in
the whole seed lot and in the same proportion. It is therefore essential that the sample must be drawn and
submitted to the seed testing laboratory as prescribed in the Rules for Seed Testing. The purpose of seed
testing is to obtain information regarding the planting value of seed in any particular seed lot. For testing to
be meaningful, seed samples must be properly collected. Seed tests often generate information which must,
by law, appear on the seed label and/or is required for obtaining a phytosanitary certificate. Both the seed
producer and the buyer rely on accurate laboratory information. Seed testing laboratories therefore must
have modern equipment and well trained analysts.
The SeedLot
A seed lot can be defined as a quantity of seed with every portion or every bag uniform within permitted
tolerances as to percentage of pure seed, inert matter, other crop seed, germination and dormant seed, weed
seed, and rate of occurrence of noxious weed seeds. A quantity of seed which is not uniform within
permitted representative tolerances should not be classified as a seed lot. Any variation should be reduced
by further conditioning, by mixing, or by separating the quantity in question into two or more uniform lots.
It is a uniformly blended quantity of seed either in containers or bulk.
Assignment of Seed Lot Number
Each seed lot shall be assigned a specific number in order to facilitate maintaining its identity,
tracing back to its origin, handling in stores, transit etc., accounting and inventory maintenance
and referring / communicating about a certain quantity of seed. The procedure for assigning lots
numbers is given below.
The lot number will have four parts. Each part will signify and conform to the details given
as under.
First Part: This shall be called the “Month-Year Code” and will indicate the month and year
inwhich the concerned seed crop was harvested.
Second Part: This shall be called the “Production Location Code” and will indicate the State or
Union Territory, where the concerned seed field(s) was / were located. For this purpose, each State
and Union Territory is allotted a permanent numerical and the same shall be used while assigning
the lot number.
Third Part: This shall be called the “Processing Plant Code” and will indicate the seed
processing plant where the relevant lot was processed. For this purpose, the Certification Agency
shall allot a numerical commencing from 01 to each seed processing plant within its jurisdiction
irrespective to which it belongs.
Fourth Part: This shall be called the “Seed Produce Code”. It will indicate ultimate serial number
of an individual lot. The procedure for assigning this code will be based on unit of certification.
For this purpose, the Certification Agency shall allot a numerical commencing from 01 to each
unit of certification.
All the four parts of the lot number shall be written in series with a „dash (-)‟ between
first, second, third and fourth parts to distinctly indicate the code number of each part. An example
is shown below:
Lot No. --- MAY 88-12-01-01

2. MAY88 -- Seed harvested in May 1988
12 -- Seed crop raised in Madhya Pradesh
01 -- Seed processed in a processing plant identified as number 01 by the
Madhya Pradesh State Seed Certification Agency
01 -- Seed Produce Code which will trace to the particular unit of certification
Sample: It is the representative of homogenous seed lot and used for seed quality analysis in the seed
testing laboratory. It ensures that the small size of sample should truly represent all the constituents of
seed lot in same proportion. Sampling refers to Drawing a small quantity of seeds from various
portions of a seed lot in such a way that the sample should contain the same constituents as that of
entire seed lot.
The object of sampling is to obtain a sample of 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. In order to
get a true picture of the entire seed lot, it is essential that the sample taken is representative.
Three categories of samples are received in a SeedTesting Laboratory
Service samples: Seed samples sent by either farmers or growers or any individuals to seed testing
laboratory for testing, for the purpose of Truthful Labeling (TFL).
Official samples: The samples which are taken by the seed law enforcement authorities,particularly
Seed Inspectors (SI), at any point of seed marketing channel in order to check the quality of the seed
lot.
Certified samples: The samples which are taken by the certification agencies after processing, in
order to determine whether the sample satisfies the standards prescribed for that category. Based on
the results obtained from Seed Testing Laboratory (STL), the Certification Agency (CA) decides
whether to issue certification tags or not.
In order to obtain certified samples, a prescribed procedure is followed which includes four
steps viz., drawing of primary sample, composite sample, submitted sample and working sample.
Primary sample: When a seed lot is sampled either in container or from bulk (heap, bins, wagons,
processing streams), several individual samples which are drawn from different containers or from
different parts of the bulk is called primary samples. i.e., each probe or handful sample of uniform
quantity drawn from heap or bag or bin is called primary sample.
Composite sample: All the primary samples that are pooled or combined together in a suitable
container is called composite sample.

3. Submitted sample: Suitably or properly reduced size of composite sample which is submitted to
the seed testing laboratory is called submitted sample. The maximum size of submitted sample
shall be 1000 g for seed quality tests.
Working sample: It is a suitably reduced required quantity of sample obtained from the submitted
sample with which quality tests are being made in the Seed Testing Laboratory. The working
sample shall contain at least 2500 seeds, subject to a minimum of 0.5 g and a maximum of 1000 g.
Sub-Sample: Sometimes the term sub-sample is also used in seed testing laboratory. Subsample is
the portion of a sample obtained by reducing the sample using one of the sampling and dividing
methods.
Sampling intensity
The following is the sampling procedure when seed is stored in bags or other container of
similar capacity that are uniform in size:
Up to 5 containers Sample each containers, but at least 5 primary samples
6 to 30 containers Sample 5 containers or one in every 3 containers
31 to 400 containers Sample 10 containers or one in every 5 containers
400 or more containers Sample 80 containers or one in every 7 containers

4. The following procedures should be followed when seeds are stored in bulk in bins or
heaps or processing streams:
Up to 500 kg At least 5 individual samples
501 to 3000 kg One sample for each 300 kg, but not less than 5 samples
3001 to 20000 kg One sample for each 500 kg, but not less than 10 samples
20001 kg and above One sample for each 700 kg, but not less than 40 samples
When the seeds are in small containers such as tins, cartons or pockets, 100 kg weight of
seed is taken as one basic unit and the small containers are combined to form sampling units not
exceeding this weight (eg. 20 containers of 5 kg; 33 containers of 3 kg; 100 containers of 1 kg
etc.). For sampling purpose, each unit is regarded as “one container” and the sampling intensity
prescribed as in the case of containers is applied.
Sampling methods
1. Mechanical sampling: It is a sampling technique followed using the various equipments such
as Nobbe trier, sleeve type trier or stick trier (with compartments or without compartments),
thief trier, cargo sampler, pelican sampler, automatic sampler, etc.,
2. Hand sampling: This method is applicable for non-free flowing or extremely chaffy seeds
likegrass seeds, cotton (fuzzy) seeds, Andropogan spp, Cenchrus spp., Dichanthium spp,
Stylosanthes and other genera of tree and shrub seeds like, Acer, Ailanthus, Cedrela, Fraxinus,
Quercus, Juglans, Populus and Tectona. The major disadvantages in hand sampling are (i) time
consuming and (ii) not possible beyond 30-40 cm depth.
Sampling equipments:
1. Thief trier: It is made up of metal with pointed tip and with a groove running across the
entiretrier length to collect the seed. It is fixed with a metal or wooden handle. This is used to
collect sample horizontally but not vertically.

5. The disadvantages in using this trier are:
 Samples cannot be taken at desired depth since the length is less
 Since having pointed tip, it may cause damage to the seed and gunny bags
 Not suitable for bulk sampling, unable to take the samples from different layers or part of
the seed lot.
2. Nobbe trier : It is a pointed tube, long enough to reach the centre of the bag, with an
ovalshaped hole near the pointed end or with a groove running across the entire trier length.
The trier should be inserted with the hole opening downward at 30 degree angle to horizontal
until it reaches the centre of the bag. Then the trier is revolved to 180 degree to bring the hole
opening to upward position and withdrawn with the increasing speed, so that the quantity of
seed obtained from the successive locations is increased. It is suitable for bag sampling but not
for bulk sampling. Vertical sampling is not possible. It is named after Frederick Nobbe, the
father of seed testing.
3. Sleeve or stick trier: It consists of a hollow brass tube inside a closely fitted outer shell or
sleeve which has a solid pointed end. The tube and sleeve have a number of open slots (holes)
in their walls in such a way that when the tube is turned, the slots in the tube and sleeve are in
line. When the trier is inserted into the bag, seeds flow into the cavity of the tube and when
given half turn, the openings are closed. The tube varies in length and diameter being designed
for different kinds of seed and various sizes of the containers. The number of slots may also
vary from 6 to 9. The trier should be inserted only in closed position. Care should be taken in
closing to avoid damage to the seeds. Two types of sleeve triers are available i.e., with
compartment (slots are separated with wall so that we can collect samples from different layers
vis-a-vis from each slot) and without compartment (hence mixing of seeds from different layer
is possible).

6. Bag sampling method (using triers)
Methods of obtaining working samples
In order to derive „representative‟ working samples from the „submitted sample‟ received
in the Seed Testing Laboratory, „mixing and dividing‟ of samples have to be performed.
Methods used for mixing and dividing the seed samples in laboratory are: Mechanical
dividing using the devices like conical or soil or centrifugal divider, random cup method; modified
halving method; spoon and spatula method; and hand halving method. However, depending upon
the type of the seed and size of the sample, the method varies.
Mixing and dividing
This method is suitable for seeds which are free-flowing and non-chaffy. The apparatus
divides the sample into two halves which are again pooled and the process is repeated till satisfied
that the mixing and dividing has been done properly. Depending upon the seed, the process is
repeated till obtaining the required quantity of seed sample is obtained.
Conical or Boerner divider: It is the most commonly used divider which is working on the
principle of gravity. The divider consists of a seed hopper, a valve and a conical structure. Inside
the conical structure, there is a series of baffles with alternate channels and space which directs the
seeds into two spouts. The width of the space and channels are same. The series of baffles are
arranged in a spiral manner in such a way that they direct the seeds inward and downward towards
the spout. The channels are leading to one spout while the space leading to an opposite spout to
divide the seed samples. This divider is not suitable for chaffy seeds and checking for cleanliness
is difficult.

7. Soil divider: It has channels or ducts arranged in straight manner, a hopper, two receiving pans
and a pouring pan. Channels are about 13 mm width and total number of channels is 18. The
alternate channels are leading to one spout in one direction and the other to the spout in the
opposite direction. This divider is suitable for large size seeds and non-free flowing (chaffy) seeds
like cotton, sugarcane, Ailanthus, teak etc.
Centrifugal or Gamet divider: Here, the seeds are divided in to two halves by centrifugal force.
The divider consists of a hopper, a shallow rubber cup and spouts. Seeds flow downward through
the hopper and fall on the shallow rubber cup or a spinner. When the spinner rotates by

8. electrical force, upon spinning, the seeds scatters and falls apart into either sides and is collected
by the two stationery baffles leading to the spouts. This is suitable for small seeds and seeds which
bounce upon spinning. However, when there is a fluctuation in voltage, the speed will be variable
which leads to improper mixing and dividing.
Random cup method: This method is mainly suitable for seeds with working sample size of 10 g
or less and the seeds should not be chaffy or bouncing. In a square tray, 6-8 cups of small size are
placed inside randomly. The seeds are then poured uniformly into the tray and cups in one
direction. In next pouring, it is done at right angle to the first. The seeds that falls in to the cups are
taken as the working sample. This process is repeated till the required quantity of working sample
is obtained. The cup should be selected such that the diameter of the cup is at least 1.5 times the
length of the seed. The ratio of width and height of the cup should be 1:2. Seeds from the cups are
pooled to obtain the required quantity of working sample. The cups should be standardized for its
size according to the size of seeds, texture of seeds etc.
Spoon and spatula method: This method is suitable for very small seeds like tomato, tobacco,
amaranthus, eucalyptus, brassicas and forage seeds. It has a tray, a spatula and a spoon with a
straight edge. After thorough mixing, the seeds are poured over the tray, uniformly. Then the seeds
are taken at random using a spoon and spatula by scooping at least at 5 places simultaneously.
This is done until the required quantity of working sample is obtained.
Modified halving method: This consists of a tray with a number of cubical cups fitted inside.The
cups will be open at the top and every alternate ones will not have the bottom. After preliminary
mixing, the seeds are evenly poured as that of random cup method. When the grid along with cup

9. is lifted, approximately half the quantity will be retained in the cups leaving the remaining half in
the tray. This process is done until required quantity of working sample is obtained.
Hand halving method: In the absence of any of the methods mentioned above, this method can
be followed. In this method, the sample is divided into 4 quarters and the two of the opposite
quarters are rejected and the other half is again pooled and the processes is repeated till the desired
quantity of working sample is obtained. This method is suitable for extremely chaffy seeds.
Size of seedlot, working and submitted samples for different crop seeds
Crop Seed lot (kg)
(maximum)
Submitted sample
(g) (minimum)
Working sample
(g) (minimum)
Wheat 20000 1000 150
Barley 20000 1000 150
Paddy 20000 400 40
Sorghum 20000 900 90
Bajra 20000 150 15
Maize 40000 1000 900
Redgram 20000 1000 300
Blackgram 20000 1000 700
Bengalgram 20000 1000 1000
Greengram 20000 500 120
Cowpea 20000 1000 400
Groundnut 20000 1000 1000
Sunflower 20000 1000 200
Castor 20000 1000 500
Sesame 20000 70 7
Soybean 20000 1000 500
Cotton 20000 1000 350
Jute 20000 150 15
Tomato 10000 15 7
Brinjal and Chillies 10000 150 15

10. Bhendi 20000 1000 500
Cabbage 10000 100 10
Lablab 20000 1000 500
Cauliflower 10000 100 10
Radish 10000 300 15
Carrot 10000 30 3
Peas 20000 1000 700
Beetroot 20000 500 50
Lettuce 10000 30 3
Coriander 10000 400 40
Onion seed 10000 80 8
Pumpkin, Ash gourd 10000 350 180
Other gourds 20000 1000 500
Lucerne 10000 70 70
Turnip 10000 70 7
References:
https://seednet.gov.in/CMS/QualityControl/Seed_Testing_Manual/CHAPTER-5.pdf
M. Bhaskaran et al. (2003). Text book of “Principles of seed production and quality
control”.
https://www.seedtest.org/upload/cms/user/Chapter2editorialmerger.pdf
http://nsca-af.com/wp-content/uploads/2017/07/SEED-SAMPLING.pdf
https://hasanuzzaman.weebly.com/uploads/9/3/4/0/934025/seed_sampling.pdf