Village Agriculture, Horticulture and Sericulture Assistant · Chapter 4

Seed Technology

What to remember

Seed is a living, ripened ovule able to grow into a plant; grain is for food or feed. Good seed gives high genetic purity, physical purity, germination and vigour, and is free from weed seeds and disease.
Classes of seed pass in order: Nucleus → Breeder → Foundation → Registered (optional) → Certified; tag colours: breeder golden yellow, foundation white, certified azure blue, truthfully labelled opal green.
Pure live seed (PLS) % = purity % × germination % / 100; Seed Replacement Rate (SRR) = area sown with certified or quality seed / total area × 100.

Seed and its quality

A seed has an embryo, stored food (endosperm or cotyledons) and a seed coat. Quality seed has these attributes:

Genetic purity: true to the variety.
Physical purity: free from inert matter, other crop seeds and weed seeds.
Germination: percentage of seeds producing normal seedlings.
Vigour: ability to give strong seedlings under varied field conditions.
Health: free of seed-borne diseases and insects.
Moisture: at the safe level for storage.
Seed size and test weight (weight of 1000 seeds).

Improved varieties give benefits only if the seed is of high quality. A quality seed improves yield (often 15–20%) at little extra cost.

Seed production and classes

A variety is a group of plants with distinct features that stay stable in reproduction. Hybrid seed is made by crossing two parents and must be bought fresh every season; seed of varieties (open-pollinated or self-pollinated) can be saved for a few seasons.

Class	Produced by	Tag colour
Nucleus seed	plant breeder, genetically pure	—
Breeder seed	breeder, from nucleus seed	golden yellow
Foundation seed	from breeder seed, under supervision, in certified farms	white
Registered seed	from foundation seed (optional class)	purple
Certified seed	from foundation (or registered) seed, sold to farmers	azure blue
Truthfully labelled seed	producer's own guarantee, not certified	opal green

Principles of seed production: choose suitable climate and soil; use the right class of seed; follow isolation distance (to avoid cross pollination, e.g. rice 3 m for self-pollinated crops; much more for cross-pollinated crops like maize); rouging (removing off-types and diseased plants); field inspections by certification officers at flowering and before harvest; careful harvest, threshing and drying.

Hybrid seed production uses male sterile lines: A line (male sterile), B line (maintainer) and R line (restorer) in the three-line system (cytoplasmic genetic male sterility); the two-line system uses environment-sensitive lines. In maize, detasseling (removing the male tassels) of the female parent is done. Cotton hybrid seed is produced by hand emasculation and pollination.

Seed certification and law

Seed certification is a quality-control system to maintain genetic purity and identity. Steps: application, verification of seed source, field inspections, post-harvest inspection of processed seed, seed testing, labelling and tagging, and issue of certificate. Authority: the State Seed Certification Agency (in AP, a state certification agency under the Seeds Act).

The Seeds Act, 1966 and Seed Rules, 1968 regulate seed quality; the Seeds (Control) Order, 1983 covers dealers' licensing. The National Seeds Corporation (NSC), set up in 1963, is a central seed agency; the AP State Seeds Development Corporation (APSSDC) is the state seed agency. Minimum seed certification standards (set by the national standards) fix limits for genetic purity, physical purity, germination, moisture and other crop or weed seeds; for example certified seed of self-pollinated cereals needs high physical purity and germination at or above the minimum legal level (check the official standards before quoting a number).

Seed testing

Seed testing follows international (ISTA) rules. A submitted sample is sent to the laboratory; a working sample is drawn for each test.

Test	What it shows
Physical purity	% of pure seed, other crop seed, weed seed and inert matter
Germination	% normal seedlings; counts at first and final count days
Moisture	% moisture by oven method or meter
Viability (tetrazolium, TZ)	living tissue stains red
Vigour	strength of seedlings (e.g. accelerated ageing)
Seed health	fungi, bacteria, insects
Genetic purity	grow-out test, electrophoresis
Test weight	weight of 1000 seeds

Germination methods: between paper, top of paper, in sand or soil. Normal seedlings have all essential structures; abnormal seedlings, hard seeds, fresh ungerminated seeds and dead seeds are counted separately.

Example: purity 98% and germination 90%, so PLS = 98 × 90 / 100 = 88.2%. If a crop needs 20 kg/ha of pure live seed, the seed to buy = 20/0.882 = about 22.7 kg.

Seed dormancy and treatment

Dormancy is a state in which viable seeds fail to germinate even in good conditions. Causes: hard seed coat, immature embryo, inhibitors. Breaking methods: scarification (mechanical, acid), stratification (cold moist treatment), soaking in water, potassium nitrate (KNO₃), gibberellic acid (GA₃) and light or temperature treatment.

Seed treatment protects seed and seedlings. Types: seed dressing with fungicides (thiram, carbendazim) or insecticides; seed coating and pelleting; biological treatment with Rhizobium, Azospirillum, PSB or *Trichoderma*; seed hardening (soaking in water or salt solution and drying back to improve drought tolerance); seed priming (partial hydration to speed up germination). Treat seed with fungicide first, then with biofertilizer, and let it dry in shade before sowing. Always use gloves and treat away from food.

Seed processing, storage and distribution

Processing steps: drying, pre-cleaning, cleaning (air-screen cleaner), grading by size, treatment, packing and labelling. Safe moisture for seeds in ordinary storage is about 8–12% depending on crop; for sealed containers it is lower (about 5–6%). Oil-rich seeds (groundnut, sunflower) lose viability faster.

Harrington's thumb rules: (1) Each 1% reduction in seed moisture (between about 5 and 14%) doubles the storage life; (2) Each 5.6 °C (10 °F) reduction in storage temperature (between 0 and 50 °C) doubles the storage life.

Seed deterioration is caused by high moisture, high temperature, storage pests and fungi. Seed stores must be dry, cool, clean and aerated. Seeds are packed in cloth, jute, polythene or aluminium foil bags, and storage pests are controlled by fumigation and good hygiene. Seed Replacement Rate shows what percentage of farmers' area is sown with quality seed; Seed multiplication ratio is the output seed per unit seed sown (high in cereals, low in cotton hybrids). Community seed production (seed village concept) lets farmers produce seed of their own area.

Seed quality in the field: practical points

Farmers can do simple checks. A rag-doll or towel germination test on 100 seeds counted after the specified days gives a quick estimate of germination before sowing. A float test in water separates light, empty or damaged seed (as in paddy in salt solution) from heavy, sound seed. Seed should be bought only from licensed dealers or the department outlets, and the bag, tag, label and bill should be kept until harvest. The label must show crop, variety, lot number, class, germination, purity, date of test and validity period. Seed older than its validity period must be retested before use.

Good seed management at the village level includes using certified seed on a rotation basis (replace seed regularly in self-pollinated crops, every season for hybrids), proper threshing and drying on clean floors without mixing varieties, storage away from fertilizer and pesticides, and treating seed before sowing. These steps raise the seed replacement rate and the yield. The Village Agriculture Assistant guides farmers on seed selection, treatment and sowing time and links them to seed supply at the village agriculture centre.

Exam traps

Breeder seed tag is golden yellow; foundation white; certified azure blue.
Truthfully labelled seed is not certified; it carries the producer's guarantee.
Germination % is for normal seedlings only; viability may be higher than germination.
Hybrid seed cannot be saved and reused; variety seed can.
Scarification breaks hard-seed dormancy; stratification needs chilling.
Seed moisture and temperature both matter: a drop of 1% moisture doubles life.
Rouging removes off-types; detasseling removes maize tassels.
Seeds Act is 1966; Seed Rules 1968; Seeds Control Order 1983.

One-liners

1. Nucleus seed is the purest class.
2. Breeder seed: golden yellow tag.
3. Foundation seed: white tag.
4. Certified seed: azure blue tag.
5. Truthfully labelled seed: opal green tag.
6. Tetrazolium stains living tissue red.
7. PLS = purity × germination / 100.
8. Rouging: removal of off-type plants.
9. Detasseling: removal of tassels in maize.
10. Seeds Act was enacted in 1966.
11. National Seeds Corporation: 1963.
12. Test weight is the weight of 1000 seeds.

Practice questions

A seed lot has physical purity 98% and germination 90%. Its pure live seed percentage is
1. 90%
2. 98%
3. 88.2%
4. 94%
Answer
C. 88.2%
98 x 90 / 100 = 88.2%.
Out of 100 seeds set to germinate, 85 produce normal seedlings. The germination percentage is
1. 92.5%
2. 100%
3. 85%
4. 15%
Answer
C. 85%
Normal seedlings / seeds sown x 100 = 85%.
In a 100 g working sample, 97 g is pure seed. The physical purity is
1. 97%
2. 100%
3. 3%
4. 94%
Answer
A. 97%
97/100 x 100 = 97%.
The weight of 1000 seeds is 25 g. The approximate number of seeds per kg is
1. 4,000
2. 40,000
3. 2,500
4. 25,000
Answer
B. 40,000
1000 g / 25 g x 1000 = 40,000.
A crop needs 25 kg/ha of seed with 100% germination. If the germination is 80%, the seed rate to use is
1. 25 kg
2. 20 kg
3. 45 kg
4. 31.25 kg
Answer
D. 31.25 kg
25 x 100 / 80 = 31.25 kg.
Certified seed was sown on 30 ha out of 120 ha. The Seed Replacement Rate is
1. 30%
2. 25%
3. 4%
4. 75%
Answer
B. 25%
30/120 x 100 = 25%.
By Harrington's rule, reducing seed moisture by 2% (within the range) changes storage life by about
1. 2 times
2. 8 times
3. no change
4. 4 times
Answer
D. 4 times
Each 1% drop doubles life, so two points give 2 x 2 = 4 times.
By Harrington's rule, reducing storage temperature by 11.2 °C (twice 5.6 °C) changes storage life by about
1. 4 times
2. 2 times
3. half
4. 8 times
Answer
A. 4 times
Each 5.6 °C drop doubles life, so two steps give 4 times.
A sample of 50 g loses 5 g on oven-drying. The moisture content on wet basis is
1. 90%
2. 5%
3. 10%
4. 11.1%
Answer
C. 10%
5/50 x 100 = 10%.
Purity 96% and germination 75%. The pure live seed % is
1. 75%
2. 85.5%
3. 72%
4. 96%
Answer
C. 72%
96 x 75/100 = 72%.
The class of seed produced by the plant breeder from nucleus seed is
1. registered seed
2. foundation seed
3. certified seed
4. breeder seed
Answer
D. breeder seed
Breeder seed comes from nucleus seed.
The tag colour of breeder seed is
1. opal green
2. golden yellow
3. azure blue
4. white
Answer
B. golden yellow
Breeder seed has a golden yellow tag.
The tag colour of foundation seed is
1. white
2. golden yellow
3. purple
4. azure blue
Answer
A. white
Foundation seed is tagged white.
The tag colour of certified seed is
1. opal green
2. golden yellow
3. azure blue
4. white
Answer
C. azure blue
Certified seed is tagged azure blue.
Truthfully labelled seed carries a tag of colour
1. azure blue
2. opal green
3. white
4. golden yellow
Answer
B. opal green
Truthfully labelled seed has an opal green tag.
Certified seed is produced from
1. nucleus seed only
2. breeder seed directly only
3. farmer-saved grain
4. foundation seed
Answer
D. foundation seed
Certified seed is produced from foundation (or registered) seed.
The Seeds Act was enacted in
1. 1966
2. 1968
3. 1963
4. 1983
Answer
A. 1966
The Seeds Act is of 1966.
The Seeds (Control) Order, which licenses seed dealers, was issued in
1. 1990
2. 1968
3. 1966
4. 1983
Answer
D. 1983
Seeds (Control) Order dates to 1983.
The National Seeds Corporation was set up in
1. 1983
2. 1963
3. 1975
4. 1966
Answer
B. 1963
NSC was formed in 1963.
Removal of off-type and diseased plants from a seed production field is called
1. rouging
2. detasseling
3. thinning only
4. pruning
Answer
A. rouging
Rouging keeps the crop pure.
Removal of the male tassel in maize seed production is
1. emasculation of cotton
2. rouging
3. detasseling
4. topping
Answer
C. detasseling
Detasseling is done on the female parent.
Distance kept between a seed crop and another variety of the same crop to avoid cross pollination is
1. spacing
2. seed rate
3. border row only
4. isolation distance
Answer
D. isolation distance
This is the isolation distance.
The male-sterile line in the three-line system is the
1. A line
2. R line
3. C line
4. B line
Answer
A. A line
A is male sterile, B maintainer, R restorer.
The restorer line is denoted by
1. S line
2. A line
3. R line
4. B line
Answer
C. R line
R restores fertility in the hybrid.
A hybrid variety's seed, if saved from the crop and sown again, generally
1. does not germinate at all
2. gives lower yield and uneven plants
3. gives a higher yield
4. gives the same hybrid
Answer
B. gives lower yield and uneven plants
Hybrids segregate in the next generation.
The test that uses staining of living tissue red is the
1. float test
2. oven test
3. grow-out test
4. tetrazolium test
Answer
D. tetrazolium test
TZ stains living tissue red.
The breaking of hard-seed dormancy by mechanical or acid treatment is
1. hardening
2. scarification
3. priming
4. stratification
Answer
B. scarification
Scarification weakens the seed coat.
Cold moist treatment to break dormancy is
1. stratification
2. scarification
3. pelleting
4. fumigation
Answer
A. stratification
Stratification is chilling in moist medium.
Which chemical is used to break dormancy?
1. Urea
2. Gypsum
3. Potassium nitrate
4. Thiram
Answer
C. Potassium nitrate
KNO₃ and GA₃ break dormancy.
Thiram and carbendazim are used for
1. weed control
2. seed marking
3. seed treatment against fungi
4. breaking dormancy
Answer
C. seed treatment against fungi
They are fungicides for seed dressing.
Seed treatment with Rhizobium is meant for
1. legume seeds
2. cereal seeds
3. oilseed seeds like mustard only
4. vegetable seeds only
Answer
A. legume seeds
Rhizobium works for legumes.
Soaking seeds in water or salt solution and drying them back to improve drought tolerance is
1. seed fumigation
2. seed hardening
3. seed coating
4. seed grading
Answer
B. seed hardening
This is seed hardening.
Partial hydration of seeds to speed up germination is
1. scarification
2. pelleting
3. vernalisation
4. seed priming
Answer
D. seed priming
Priming starts the early metabolic steps.
Safe seed storage requires seeds that are
1. dry, cool and clean
2. exposed to light and rain
3. mixed with grain
4. moist and warm
Answer
A. dry, cool and clean
Low moisture and temperature keep viability.
Which seeds lose viability faster in storage?
1. Starchy cereals like sorghum
2. Oil-rich seeds such as groundnut and sunflower
3. Dry pulses at low moisture
4. None of these
Answer
B. Oil-rich seeds such as groundnut and sunflower
Oil-rich seeds deteriorate faster.
Cleaning, grading, treating and packing are steps of
1. seed certification
2. seed dormancy
3. seed production
4. seed processing
Answer
D. seed processing
Processing prepares seed for sale.
The agency that inspects seed production fields and issues certificates is
1. APMC
2. NABARD
3. the State Seed Certification Agency
4. FCI
Answer
C. the State Seed Certification Agency
Certification agency verifies quality.
Seed that has passed all certification stages and is sold to farmers is
1. certified seed
2. nucleus seed
3. registered seed
4. breeder seed
Answer
A. certified seed
Certified seed is the commercial class.
Consider the statements. 1. Breeder seed carries a golden yellow tag. 2. Foundation seed carries a white tag. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
C. Both 1 and 2
Both are correct.
Consider the statements. 1. Hybrid seed can be saved for repeated use with the same vigour. 2. Variety seed of self-pollinated crops can be saved for some seasons. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
B. 2 only
Hybrids lose vigour when saved.
Consider the statements. 1. Germination test counts only normal seedlings. 2. Tetrazolium test indicates viability. Which is/are correct?
1. 1 only
2. Both 1 and 2
3. 2 only
4. Neither 1 nor 2
Answer
B. Both 1 and 2
Both are correct.
Consider the statements. 1. Rouging is the removal of off-types. 2. Detasseling is a practice in cotton hybrid seed production. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
Detasseling is a maize practice.
Consider the statements. 1. Seeds Act, 1966 regulates seed quality. 2. Truthfully labelled seed is certified by the State Seed Certification Agency. Which is/are correct?
1. 2 only
2. Both 1 and 2
3. Neither 1 nor 2
4. 1 only
Answer
D. 1 only
Truthfully labelled seed is the producer's own guarantee.
Seed Replacement Rate indicates
1. the germination percentage
2. the seed moisture
3. the percentage of area sown with quality seed in place of farm-saved seed
4. the seed rate per hectare
Answer
C. the percentage of area sown with quality seed in place of farm-saved seed
SRR is an adoption measure.
Seed vigour is the
1. seed moisture
2. weight of 1000 seeds
3. isolation distance
4. ability to produce strong seedlings under varied field conditions
Answer
D. ability to produce strong seedlings under varied field conditions
Vigour reflects field performance.

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