1. DOCTRAL SEMINAR
Role of Morphological Markers and DUS
characters in Varietal Purity Testing
Department of Genetics and Plant Breeding,
Allahabad School of Agriculture,
SAM HIGGINBOTTOM INSTITUTE OF AGRICULTURE,
TECHNOLOGY & SCIENCES, ALLAHABD U.P
Ph.D (Ag) SST
Seminar In charge
Dr. P.K. RAI
• From the ancient time, many plant species have been domesticated far away, from the region of
their origin, by seeds.
• It became a tradition to save some grains or purchase some grains or exchange some grains for
planting the next crop.
• Seed production or maintenance of a genetic constitution of the seed is a quite specialized and
scientific procedure and is not similar to general food crop production.
• It is important that seed of a new and superior variety should be multiplied and made available
in quantities as soon as possible so as to benefit the farmers.
• The characters of the ideal seeds are it should be true to its type, free from admixture of other
variety of seeds, have high percentage of germination and free from seed born diseases.
3. • various steps to be followed in order to maintain the genetic purity and important once
• Providing adequate isolation to prevent contamination by natural crossing or
• Rouging of seed fields, prior to the stage at which they could contaminate the seed
• Periodic testing of varieties for genetic purity
• Avoiding genetic shift by growing crop in areas of their adaptation only.
• Certification of seed crops to maintain genetic purity & quality seed.
• Adopting generation system (the seeds produced is restricted to four generation only
i.e. starting from breeders seeds) and the seeds can be multiplied up to three more
generation i.e. foundation, registered and certified.
• Grow-out-tests: to confirm the genetic purity of the seed lot.
4. GROW OUT TEST (GOT)
• Varieties being grown for seed production should periodically be tested for
genetic purity by Grow-out test, to make sure that, seed being maintained in their
• The seed production organization or seed certification agency, mostly draw a
sample of seed and grows it in the field to check, the purity of the variety by
comparing the standard/norms/characters related to that crop variety to take
purity test or analysis, to determine how much % of the admixture is present in
• GOT is conducted to determine the genetic purity of a given seed lot of a
• The size of submitted sample will be as follows.
• 1000 grams: for Maize, Cotton, Groundnut, Soybean and species of other genera
with seed of similar size.
• 500 grams: for Sorghum, Wheat, Paddy and species of other genera with seed of
• 250 grams: for Beta and species of other genera with seed of similar size.
• 100 grams: for Bajra, Jute and species of other genera.
• 250 tubers/planting stakes/root, sweet potato and other vegetatively propagating
• While raising a test crop, standard and recommended agronomic/ cultural practices (e.g.,
field preparation, size of the plot, row length, distance between rows, distance between
plants, irrigation and fertilization), in respect of individual crops are to be followed both
for the unknown sample and its control.
• The possibility to prove the genuineness of a cultivar by Grow Out Test is based on
hereditary characteristics of the plants.
• The certification Agency may change the specification if considered necessary.
• The recommended for row length, distances, spacing for some important crops
are indicated in the following tables.
• All plants are to be studied keeping in view the distinguishing characters described
for the cultivar both in the test crop as well as the control.
• Observations are made during the full growing period, or for a period specified by
organizing breeding institute and deviations from the standard sample of the same
variety are recorded. At suitable development stage the plots are examined
carefully, and plants which are obviously of other cultivar are counted and
• On the basis of the number of plants required for taking observation is depended on
maximum permissible off types which are as follows.
10. Minimum permissible
Minimum genetic purity
No. of plants required
Sample for observation
0.10 99.9 4,000
0.20 99.8 2,000
0.30 99.7 1,350
0.50 99.5 800
1.00 and above 99.0 and above 400
11. CALCULATION AND INTERPRETATION OF THE RESULTS
Percentage of other cultivars, species found must be calculated up to first decimal place.
While interpreting the results, tolerances should be applied by using the reject number
for prescribed standards with reference to sample size as provided in Table
12. Standard Reject numbers for sample size of
99.5 (1 in 200) 8 *
99.0 (1 in 100) 16 8
95.0 (5 in 100) 48 24
90.0 (10 in 100) 88 44
85.0 (15 in 100) 128 64
Reject number for prescribed standards and sample size
* indicates that the sample size is too small for a valid test.
• D: Distinctness – The variety should be clearly distinguishable from any other
• U: Uniformity – The variety should be sufficiently uniform to enable its
• S: Stability - The variety should be stable in its relevant characteristics, that is, it
must remain true to its initial description even after repeated propagation.
17. PLANTING MATERIAL FOR DUS TESTING
• The quantity of planting material requirement is indicated in the individual Test
Guidelines of respective crops.
• The material submitted for DUS test should be representative of respective crops.
• The material submitted for DUS test should be representative of the candidate
18. QUANTITY OF PLANTING MATERIAL RECOMMENDED IN
NATIONAL TEST GUIDELINES (PENDING APPROVAL OF
Crops Quantity of seed (gm) Number of ear heads/panicles
Wheat 3000 100
Rice 3000 (varieties) 1500 (parental
Sorghum 1500 50
Pearl millet 1000 (hybrids) 500 (parental
Sunflower 1000 (Parental lines) 5000
(hybrids & open pollinated
Soybean 3000 -
Maize 1000 (inbreeds) 1500 (hybrid
& pollinated varieties)
19. DURATION OF “DUS” TESTS
• Usually the DUS examination requires more than one independent
growing cycles with reference to ecosystem of the variety for studying the
consistency of results.
• The candidate varieties are studied in a given location, over at least two
• For many crops, it is possible to complete two growing cycle in the same
year. The two growing cycles should be independent of each other.
20. •For plants grown in green houses, provided the time between the sowing is not too short
and the trial is randomized, at least partly, two growing cycles can overlap and still be
compared as independent.
For some crops such as fruit trees, the same plants are examined over successive years.
The condition of independence of growing cycle is also satisfied in this case.
21. TEST LOCATIONS
• Varieties of different geographical regions may require different agro-climatic growing
conditions. Different locations can be used in order to meet growing conditions of
• Some DUS testing centers might have a primary location, backed by a safety location.
Normally, only the data from primary location will be used, but in case this location
has major problem then the second one will be available to prevent the loss of one
• Even UPOV is currently exploring the circumstances in which more than one location
might be used in order to obtain independent growing cycles in a given year.
22. CRITERIA FOR DUS TESTING BASED ON
• National Test Guidelines development for individual crops and representing harmonized
approach for the testing of new varieties should form the basis of the DUS examination.
• It contains details on (I) subject of the guidelines (II) material required (III) conduct of
tests (IV) methods and observations (V) grouping of varieties (VI) characteristics and
symbols (VII) table of characteristics (VIII) explanations on the table of characteristics
(IX) literature and (X) technical questionnaire.
• The characteristics in the table follow the botanical order viz., seed (submitted), seedling,
plant (growth habits etc.), root, root system or other subterranean organs, stem, leaf
(blade, petiole, stipule) inflorescence, flower (calyx, sepal, corolla, pistil) and fruit.
23. DUS test for variety Registration and Notification
• Plant variety Protection (PVP) has been brought in to sharp focus by agreement on Trade
Related Aspects of Intellectual Property Rights (TRIP’s) which is a part of agreement
establishing world Trade organization (WTO).
• The establishment of a clear identity for a variety to be protected and registered involves the
• The variety should be clearly distinguishable from any other exiting variety it must be different
• The variety should be sufficiently uniform to enable its description (Uniformity).
• The variety should be stable in its relevant characteristics, that is, it must remain true to its
initial description even after repeated propagation (Stability).
• Varietal Purity testing through Conventional and Biotechnological Tools , (2013) .
Directorate of Seed Research, Ministry of Agriculture, Government of India, page 6-14.
• Agrawal, R.C.(2005). An overview of statistical procedure for DUS testing, NBPGR, IARI,
New Delhi, page 20-22.
• Prakash, S. (2005). Criteria for DUS testing based on morphological characters, division of
seed science and technology, NBPGR, IARI, New Delhi, page 9-13.
• Sharma, S.P.(2005). Principles and techniques of DUS testing, National Bureau of plant
genetics resources(ICAR) pusa campus, New Delhi. Page, 1-8.
• Singhal, N.C. and Agrawal, R.C. (2010). Statistical approach for examination of
Distinctness and Uniformity of the Varieties, seed science and technology, kalyani publisher