Seed Testing Laboratory

Introduction

The seed testing laboratory is the lab of seed quality control. Seed testing services are required from time to time to gain value of seed lots. To carry out these responsibilities effectively, it is necessary that seed testing laboratories are established, manned and equipped in a manner such that whatever samples are received could be analysed in the least possible time, seed quality control work and the need of seed industry are effectively met.

Plans

• General Principles

1. The physical-infrastructure and facilities should be planned on the basis of average expected workload during the peak season without undue delays. The working space should be adequate.
2. The kinds of tests to be carried out or likely to be carried out, for example, routine tests, seed health test, varietal purity tests etc., must be ascertained in advance for making provisions in the plan.
3. The selection and number of the equipment must meet requisite specifications.
4. The decent furnishing, light arrangement and other necessities should be provided so as to reduce the strain of otherwise strenuous work.

• Building

A seed testing laboratory can be housed as a separate building or it could form part of a larger building housing a Department. The entire work can be organized in a hall/or in separate rooms. The size of the building or space requirement depends upon the number of samples to be handled and the kind of tests to be done. The following space requirements for testing 10,000 samples per year may serve as a guideline.

a. Rooms

Sample receipt and preparations room

Size of room (Meters) 3 x 3.6

Moisture Test room

Size of room (Metres) 3 x 3.6

Purity room

Size of room (Metres) 6 x 6

Seed Health tests room (2 nos.)

Size of room (Metres ) 4 x 6

Special tests

Size of room (Metres ) 6 x 6

Sample storage

Size of room (Metres ) 4.5 x 6

2. (I) Green House (wire mesh enclosure): total area requirement should be 27.0 sq.metres

(II) Glass House: total area requirement should be 27.0 sq. metres.

c. Grow-out test plot

The purity room, in particular, should have abundant natural non-glare light.

• Staff

The number of workers in the seed testing laboratory should be related to the number of samples, crop species to be handled and kind of tests to be performed for a laboratory handling 10,000 samples per year.

Staff requirement of a seed laboratory

1. Officer incharge,

2. Senior seed analysts

i.  Purity

ii. Germination

iii. Seed Health

iv. Special Tests e.g. varietal purity

3. Junior Seed Analysts

i Purity

ii. Germination

iii. Seed Health

iv. Special Tests e.g. varietal purity

4. Laboratory Attendants (one for each room)

5. Laboratory Asstts. (one for each of the Analysts)

6. Accounts Officer

7. Accounts clerk

8. Store keeper

9. Refrigeration Mechanic (foreman)

10. Peons

• Equipment

The rules for testing seeds include the type of equipment and its specifications. Only the best available should be purchased.

List

1. General

1. Seed sampling and dividing

Seed triers (assorted sizes)
Boerner divider
Gamet divider
Soil type divider

2. Samples storage boxes and racks

3. Laboratory models of following

Air screen cleaner
Disc separator
Precision grader
Spiral separator
Others (if available)

4. Balances

Single pan (top loading)
Analytical Balance

5. Purity Work Boards

6. Germinators

Cabinet germinators
Walk-in-room germinator

7. Refrigerator

8. Sand Sterilize

9. Ovens

10. Grinding mill

11. Stereobinocular Microscope

12. Incubators

13. Autoclave

14. U V Lamp

15. Gel Electrophoresis Unit

16. Miscellaneous equipment

Kilogram per hectolitre apparatus
Seed blower
Seed scarifier
Moisture Meter (electric)
Hand Sieves

Management

• Receipt and registration of seed samples

The samples received in the laboratory should be entered in a pre-printed register or forms and assigned a test number to be used in all the analysis. The information, namely, name of the sender, type of sample, kind of tests required, crop, variety and class of seed etc. should be properly recorded.

For speedy operation it would be desirable to simultaneously prepare separate seed analysis cards and envelop for working samples. The test no. would invariably be written on each card and the envelope.

• Moisture Test

The samples intended for a moisture test. These samples after assigning the test no. should be passed on for moisture testing analysis without unnecessary delay.

• Working sample

After entering the sample the next step is to prepare the working sample(s) for various tests. The seed tests the first objective should be to prepare a working sample for the germination/viability. Subsequently, the working sample envelopes for the various tests alongwith the corresponding analysis card should be a serially placed in sample tray for sending to the concerned section.

• Routine Tests

In a seed testing laboratory, germination test, purity test, test for other seeds and moisture test are known as routine test. Where the analysis for diseased seeds or other variety seeds is also desired on the routine basis as in the case of certified seed samples for the issuance of seed certification tags these tests should also be included in the routine tests.

• Other tests

Every effort should be made to complete these tests as quickly as possible. These should be carried out as per available procedures.

• Reporting of results

After the tests have been completed, the results are reported on a printed form, known as, seed analysis certificate in the requisite manner. One of the common complaint against seed testing laboratories is "length of time", that is, the days taken in sending the report. The result of seed samples received from seed inspectors under the provision of seeds. Act should be communicated within 21 days from the date of receipt but not later than 30 days in any case.

• Storage of guard samples

The submitted samples on which reports are issued should be stored after analysis for one year from the date of issue of reports, in conditions calculated to minimize any change in quality.

• Maintenance of records

To serve the needs of seed certification, farmers and other applicants, it is essential that records are immediately available for any sample tested during the current year, season, or at any other specified time. The records should be maintained in such a manner that any information needed can be traced immediately.

Probable Causes of Discrepancies in Seed Test Results

As a rule the seed is testing, results must be accurate and reproducible within comparable limits. However, the results obtained at two different seed testing laboratories may vary, although the same rules are followed.

Causes

• Heterogeneity of seed lots

This is the most important cause of variation. No two samples taken from the same container or the same lot of seeds are likely to be identical. Inadequate mixing or blending interferes with random distribution and therefore lowers the chances of getting a representative sample from a seed lot. Also, genetic heterogeneity, variability in soil and degree of pest and disease incidence during seed maturition combined with variations in operations during harvesting, drying and conditioning are some of the major causes of heterogeneity in a seed lot.

• Sampling and Equipment

Defective sampling, substandard equipment and uncontrolled differences in the application of test procedures are other important sources of variation in test results.

• Experience

Expertise of analysts making and/or reporting the test results vary. This may also lead to variation. It should be the endeavor of all seed analysts in the seed laboratory to stick to the procedure prescribed in the rules for seed testing. This would help in bringing uniformity, accuracy and reproducibility in test results.