Seed
Testing
Seed certification schemes, controlled pedigree systems and rules and regulations for seed growing and distribution are all aimed at maintaining cultivar trueness and purity of seed. Inspite of this, possibilities always exist for unwanted seeds of other cultivars or other types to contaminate the originally pure seed lots. Causes of contamination include: (1) natural crossing with another cultivar especially in open pollinated crops, (2) mutation,
3) unclean harvesting equipment, (4) carelessness at the processing plant and (5) mistakes in bagging and tagging.
To discover and control such contamination pre- and pest-control tests are conducted by means of cultivar identification and purity determination.
Cultivar purity or genuineness of a cultivar is tested by means of heritable characters(morphological, physiological, chemical etc.) of seeds, seedlings, plants or stands.
An authentic standard sample must be available for comparison which is required to be treated and examined in the same way as the sample under test. In other words, standard as well as test samples compared at the same stage of development grown under identical environmental conditions.
Characters for Varietal Purity Test
The possibility to prove genuineness of a cultivar by field plot test is based on the hereditary characteristics of the plant.
The characteristics used to distinguish varieties may be either (1) qualitative or (2) quantitative.
Qualitative characteristics are those which show discrete discontinuous states with no arbitrary limit on the number of stages. Whereas quantitative characteristics are those which are measurable on a one dimensional scale and show continuous states with no arbitrary limit on the number of stages. Whereas quantitative characteristics are those which are measurable on a one dimensional scale and show continuous variation from one extreme to the other.
Qualitative characteristics are normally recorded visually, whereas quantitative characteristics can be measured, in many cases, however, a visual assessment or, if applicable, other sensory observations(e.g.taste, smell) are sufficient.
A combination of laboratory and field plot methods may be used to determine the cultivar truness and genetic purity of the sample. Laboratory methods based on examination of morphological seed characters, colour reaction to certain chemical treatments, properties of seedlings, response of seedlings to controlled environment and growth stimulants and stable plant characters are used to detect cultivar trueness. Therefore, the methods for varietal purity are divided in the following groups:
A. Examination of seed in the laboratory
B. Examination of seedlings grown in a growth chamber or green house.
C. Field plot tests or grow-out test.
Weight of Submitted samples
For conducting cultivar purity test, the amount of sample which should be submitted is given below.
Minimum weight of the submitted sample
1000 gm - for maize, cotton, groundnut, soybean and species of other
genera with seeds of similar size:
150 gm - Cotton Hybrid;
500 gm - for sorghum, wheat, paddy and species of other genera with seeds
of similar size;
250 gm - Beta and species of other genera with seeds of similar size;
100 gm - for bajra, jute and species of all other genera.
250 tubers/ - seed potato, sweet potato and other vegetatively
plating stakes/roots/ propagating crops
corms
Observation:
All plants must be examined for distinguishing characters during the whole growing period or for a period specified by originating breeding institute and deviations from the standard sample of the same variety are recorded. A suitable development stage the plots are examined carefully, and plants which are obviously of other cultivar or crop are counted and recorded.
Percentage of other cultivar , other species or aberrant found may be calculated upto first decimal place.
(The net plot size given is about 10% more than the area actually required)
|
Crop |
Off type % |
No.of plants/head required |
Row Length(m) |
Spacing between |
No.of Plants Per row |
No.of rows required |
Net plot Size m 2 |
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|
F |
C |
F |
C |
|
Plants (cms) |
Rows (cms) |
|
F |
C |
F |
C |
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1.Paddy
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Early |
0.050 |
0.2 |
8000 |
2000 |
6 |
15 |
20 |
40 |
200 |
50 |
264 |
16 |
|
|
Late |
0.050 |
0.2 |
8000 |
2000 |
6 |
25 |
30 |
24 |
334 |
84 |
661 |
150 |
|
|
2.Wheat |
0.050 |
0.2 |
8000 |
2000 |
6 |
2 |
25 |
300 |
27 |
7 |
45 |
12 |
|
|
3.Bajra |
0.010 |
0.05 |
8000 |
4000 |
6 |
10 |
60 |
60 |
134 |
67 |
531 |
265 |
|
|
4.Sorghum |
0.010 |
0.05 |
8000 |
4000 |
6 |
10 |
45 |
60 |
134 |
67 |
400 |
200 |
|
|
5.Black Gram Chick pea Green Gram Lentil
|
0.10 |
0.20 |
4000 |
2000 |
6 |
10 |
30 |
60 |
67 |
34 |
133 |
66 |
|
|
6.Cowpea |
0.10 |
0.20 |
4000 |
2000 |
6 |
10 |
45 |
60 |
67 |
34 |
200 |
100 |
|
|
7.Pea |
0.10 |
0.50 |
4000 |
2000 |
6 |
10 |
45 |
60 |
67 |
34 |
200 |
100 |
|
|
8.Pigeonpea |
|
|
|
|
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|
|
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|
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Annual |
0.10 |
0.20 |
4000 |
2000 |
9 |
30 |
60 |
30 |
134 |
67 |
800 |
400 |
|
|
Biannual |
0.10 |
0.20 |
4000 |
2000 |
9 |
45 |
75 |
20 |
200 |
100 |
1485 |
742 |
|
|
9.Soybean |
0.10 |
0.50 |
4000 |
800 |
6 |
10 |
45 |
60 |
73 |
15 |
197 |
41 |
|
|
10.Groundnut |
0.10 |
0.20 |
400 |
2000 |
6 |
10 |
40 |
60 |
67 |
34 |
177 |
89 |
|
|
11.Rape& Mustard |
0.10 |
0.50 |
4000 |
800 |
9 |
15 |
45 |
60 |
67 |
14 |
300 |
62 |
|
|
12.Sesamum |
0.10 |
0.20 |
4000 |
2000 |
6 |
15 |
30 |
40 |
100 |
50 |
198 |
99 |
|
|
13.Sunflower |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Variety |
0.10 |
0.20 |
4000 |
2000 |
9 |
30 |
60 |
30 |
134 |
67 |
796 |
398 |
|
|
Hybrid |
0.20 |
0.50 |
2000 |
800 |
9 |
30 |
60 |
30 |
67 |
27 |
400 |
160 |
|
|
14.Okra |
0.10 |
0.20 |
4000 |
2000 |
9 |
30 |
60 |
30 |
134 |
67 |
796 |
400 |
|
|
15.Cotton |
|
|
|
|
|
|
|
|
|
|
|
|
|
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Variety |
0.10 |
0.20 |
4000 |
2000 |
5 |
10 |
45 |
50 |
80 |
40 |
198 |
99 |
|
|
Hybrid |
0.10 |
0.50 |
- |
400 |
5 |
10 |
45 |
50 |
- |
8 |
- |
20 |
|