Techniques of hybrid seed production in vegetable crops

1. HYBRIDSEEDPRODUCTION IN
VEGETABLE CROPS

2.  1914: Shull given the term of hybrid vigour, the superiory of F1 over its
parents
 1933: First hybrid vigour at the national level was reported in chilli
 1971: First F1 hybrid was released from IARI on bottle gourd known as Pusa
Meghdoot. After this release F1 hybrid Pusa Alankar in summer squash
and Pusa Sanyog in cucumber was released by IARI
 1973: Indo American Hybrid Seed Company (IAHSC) in private sector,
released First tomato hybrid Karnatak and capsicum hybrid Bharat
 1981: IIHR Bangalore released first F1 hybrid Arka Navneet in Brinjal

3.  Greaterproductivity
 Longer harvestduration
 Better adaptability to variable Environments
 Better tolerance to diseases andpests
 Mature earlier and more uniform produce
 Bettermarket acceptability
 Betternutritional quality

4. Techniques of hybrid seed production in
vegetable crops
1. Hand emasculation and pollination
2. Male sterility
3. Self incompatibility
4. Gynoecious line
5. Use of plant growth regulator

6. The most commonly utilized mechanisms for developing commercial
hybrids in vegetable crops
Mechanism Commercial y exploited in:
Hand emasculation+ HP
Tomato, eggplant, sweetpepper,okra, hot
pepper
Removestaminateflowers+ HP Cucurbits (bitter gourd, bottle gourd,etc.)
Male sterility + HP
Male sterility + NP
Self incompability + NP
Gynoecism + NP Cucumber, Musk melon
Tomato, hotpepper,sweet pepper
Onion, cabbage, cauliflower, carrot, hotpepper,
Petunia, Marigold, Dianthus, Zinnia
Most ofcole vegetables like broccolis,
cabbage etc.
Removestaminateflowers+ NP Cucurbits including bitter gourd,summer
squash,winter squash, etc.
HP = Hand pollination NP = Natural pollination

7. Next day opening flower buds are selected
To be done before anther dehiscence
To be done with hand/ forceps
1. Emasculation:
Flower collection
Anther cones are taken
andputthemin glas ine
envelopes
Dry anthers at
30℃ for 24 hrs
Put the dried anther
cones in a cup then
tranfer to pollen lid cup
3. Pol ination
2.Pol en Col ection

8. Limitations of Emastion
Limitations of Emasculation and Pollination
Time consuming
Labour intensive (Skill is necessary for commercial
seed production)
Increased cost of production

9. Production of large scale of F1 seeds.
Reduced cost of hybrid seed production.
Speedup the hybridization programme.
Commercial exploitation of hybrid vigour.

11. Male sterile
Male sterile
Male fertile
F1 seeds 100% male sterile
Cytoplasmic male sterility
Cytoplasmic male sterility

12. P1
P
2
Male sterile Male Fertile
Male sterile
F1
Male sterile Male Fertile
Male sterile
Back cross
♀ ♂
♂
♀

14.  Natural population
 Artificial y induced through mutagenesis
 Genetic engineering
 Protoplast fusion

15. Opena et al.,2009, Taiwan
Table 8: Different male sterile mutants in tomato.

16. 18

17. Inability to set seed from application of pollen produced on same
plant or it refers to failure of viable pollen of a given plant to
fertilise the ovules of the same plant, but it capable of fertilising
effectively theovules ofthemostotherplantofthe samevariety.
Self incompatibility occurs in more than 3000 sp belonging to 250
genera,spreadin about70families.
Self incompatibility:
Self incompatibility

18. 1.Gametophytic.
SI reaction of a pol en is determined by its own
genotype not by the genotype of the plant on which the
pol enis produced
2.Sporophytic.
SIreaction of pol en is governed by the genotype of
the plant on which the pol en is produced and not by the
genotype of the pol en.
20

19. Stable self incompatibility.
High seedsetofself pollination atbud stage.
Favorable anduniform economiccharacters.
Desirable combinationability.
21

20. Conclusion
Hand emasculation and pollination is time consuming method
but can be practiced if skilled labour available.
Tomato, Chilli, Bhendi, etc.,
Male sterility and self incompatibility are two best methods of
hybrid seed production.
GMS: Chilli
CMS: Onion, Potato, etc.,
CGMS: Chilli, etc.,
SI: Colecrops etc.,

21. Problems in exploiting in SI
In species with self-incompatibility continuous in the appearance of new
incompatibility relationships, thus causing self-incompatibility. Such mutated
forms cannot be used as parents for producing hybrids.
1. Continuous breeding in many Brassica crops may lead to complete loss
of inbreed lines. It, will therefore, be more desirable if tissue culture
techniques for propagation of parental lines are followed . Sib-Mating for
maintenance of these lines also prove useful.
2. Pseudo-incompatibility may lead to pure seed in an otherwise hybrid
seed. Reduction of strength of incompatibility by environmental factors
e.g. Elevated temperatures may weaken incompatibility or may even
break it down.

22. Break down of self incompatibility
1. Bud pollination
2. Delayed self pollination
3. Application of carbon dioxide
4. Treatment of stigma with organic solvents
5. End season pollination
6. Steel brush pollination
7. Double pollination
8. NaCl

23. Use of gynoecious lines
1. Gynoecious lines have been developed in cucumber, muskmelon,
summer squash etc. these lines are being used for the production
of hybrids. Gynoecious has been used for producing commercial
hybrids in cucumber all over the world.
2. In India, Pusa Sanyog hybrid of cucumber developed by crossing
Japanese gynoecious line and Green Long Naples has been
identified at the national levels.
3. Parthenogenic genes are also linked with the gynoecy. Thus
hybrids developed by utilizing gynoecious lines are totally female
with parthenogenic genes, and do not require pollination for fruit
set.

24. 1. Gynoecious cucumber plants are now available. It permits hybrid seed
production simply by growing the gynoecious maternal parent in the same
field as the pollen producing male parent. Natural pollination is
accomplished by bees. The number of rows of the gynoecious parents to
those of the pollinators in hybrid cucumber seed production fields may vary
but 3:1 ratio is common.
2. Gynoecious lines in cucumber are maintained by treatment with growth
regulators (GA3, silver nitrate @ 300-500 ppm or silver thiosulphate @ 400-
500 ppm at 2-4 true leaf stage) that induce male flowers to develop,
permitting self or sib-pollination . Many commercial seed lots of gynoecious
hybrid cucumber cultivars are a blend (combine or mix) of gynoecious and
monoecious types (10 % seed of monoecious types).

25. Use of plant growth regulators
1. Plant growth regulators are used to produce hybrid seed in cucurbits. Most practical
growth regulator to use in production of hybrid seeds of cucurbits is Ethephon.
2. When properly applied to the female parent of a hybrid cultivar in certain cucurbits, it can
cause the plant to produce only female flowers for such an extended period that hybrid
seed can be produced by open pollination. A ratio of one male parent row to five female
parent rows is generally used for hybrid seed production in Cucurbita pepo (summer
squash).
3. An ethrel solution (250 ppm) is used to suppress the induction of male flowers in the
female plant rows. It is applied as a spray at three stages of plant development i.e. first
true leaf, third true leaf and fifth true leaf. By the time, that two or three fertile fruits have
developed at each mother plant, the ethrel effect is gone. Further sprays would not be
effective so development of later male flowers is stopped by cutting of the plant growth
with a knife.

26. Hybrid seed production- Introduction
Hybrid varieties have been evolved in those high
valued vegetable crops that exhibit marked
heterosis
Solanaceous vegetables (tomato, eggplant,
sweet pepper)
Cucurbits (melons, cucumber, pumpkin and gourds)
Root and bulb crops (onion, radish, carrot)

27. Techniques of hybrid seed production- Tomato
Hybridizationtechniques:
Indeterminate tomato varieties staked and trained with either
single stem or double stem, while determinate varieties are
trained with 3 stems
Usually1st to 4th cluster on each branch selected
The emasculation involves in holding the corolla at the base and
with a single upward pull pick off the corolla along with all the
stamens
Usually the anthers are picked off a day before anthesis with
the help of forceps leaving the petals intact

28. Fresh pollen collection on the day of anthesis by a vibrator
are shed by vibrating the flowers
Pollens are collected in a glass tube or on a glass plate
from the male line and are transferred to the stigma by
finger orby inserting the stigma into a glass tube
containing the pollen grains.
Left over pollen grains in the glass tube are not used on
the next day because its viability is reduced considerably

29.  Physiological Parameters Affecting Tomato seed
Yield andVigor
 Prolonged high temperature affect pollen fertility and
physiology offertilization leading to poor seed set
 Age of pollen and stigma, abundant or scarce
pollination, height of inflorescence and fertilizer
application exert an influence on vigor of plant

30. Seed extraction and Drying
By fermentation method
By acid oralkali treatment: 10cc or36% NaOH
added in4kg tomato pulp for15 minutes.
Seed Yield
1kg tomato produce 3-4g of seed yield. Av. Seed
yield: 60-70kg/ha

31. Techniques of hybrid seed production - Eggplant
and Pepper
Manifestation of Heterosis:
Heterosis in sweet pepper ranged 35-40%
and Eggplant 50-150%
In eggplant it is manifested by earliness, fruit
number per plant & fruit weight
Sweet pepper: plant height, days to flower, fruit
weight, early and total yield

32. Hybridizationtechniques:
Stigma is receptive a day priortoanthesis in eggplant
Budpollination possible giving good fruit set andseed yield
In sweet pepper, emasculation done a day prior to anthesis, whereas,
pollination done inthe morningon theday of anthesis
Natural cross pollination ranged from0.2-46.8% in eggplant flowers
Pepper flowers are visited by honey bees occasionally. Fresh pollen grains
are collected on the day of anthesis by a vibrator and can be stored for a
period of 1 to 2 months at O°C using silica gel for proper drying of the
pollen grains

33. Use of Male Sterility in Hybrid Seed Production in
Eggplant and Sweet Pepper
Male sterile lines available in eggplant (genic male sterility) &
sweet pepper (genic and cms) but not successful at
commercial seed production
Seed set on male sterile lines ranged from 46-67% in
capsicum
Cytoplasmic male sterility used now in chilli pepper to produce
F1 hybrid commercially by several seed companies

34. SeedExtraction
Eggplant harvested 50-55 days after anthesis and stored for
10 days forpost harvest ripening
Sweet pepper: 60-65 days after anthesis
Ripe fruits crushed and seeds separated by washing.
Dry air at 28-30ºC
Eggplant: 150-200kg/ha
Peppers: 100-200kg/ha. 1kg yields 5-7g of seed.
SeedYield

35. Techniques ofhybridseed production- Cucurbits
Steps of Hybrid Seed Productionin
Cucurbitaceous Vegetables
Production of inbred lines by inbreeding for3 to 5 generations.
Selection of inbred parents through combining ability tests and potential
hybrid production ability.
Production of hybrid seeds ( Preferably single cross hybrids and pistilate
parent preparation is relatively easy, and single fruit produces quite a
large number of seeds)
Maintenance of inbred parents

36. Techniques of hybrid seed production- Watermelon
Technique of Hybrid Seed Production
Hybrid seeds of watermelon can be produced
by two ways
1. Through artificial pollination.
2. Removal of maleflower and use of insect
pollination.

37. 1. Artificial po lination:
 Field lay-out
 Selection of female flowers
 Bagging of female & male flowers
 Collection of male flowers
 Period of pollination
 Seed fruitmanagement
 Harvesting
 Extraction, washing and drying of seeds
 Seed yield 150-300kg/ha based on varieties, extent of pollination & field
condition

38. 2. Removal of male flowers & Use of Insect Pollination:
 Inthis technique, male flowers offemale plant completely
removed before opening
 Fruits fromfemale parent harvested as crossed fruitsand
othervariety as srlf fruitof male variety
 Used incommercial hybrid seed production
 Also referred as crossing block method

39. Heterosis in Onion:
Ranged from 14-67%. It is manifested in uniform
bulb size, bulb weight & efficient source sink ratio
Male Sterility in Onion:
Controlled by combination of cytoplasmic factor ‘5’
together with recessive nucleus gene in its homozygous
form
Techniques of hybrid seed production- Onion

40. Hybrid Seed ProductionTechniques
For the production of hybrid seed in onion, male and
cytoplasmic female lines planted in the ratio of 2:8
Success of hybrid seed production depends upon the
pollen distribution pattern from fertile to sterile plants in
the crossing block

41. Factors Affecting Hybrid Seeds inOnion
Weak inbred lines
Abnormalflorets where ovary started todevelop but failed to
produce seed
Aborted ovule
Excessive heat damaging the flowers
Seed Yield
Hybrid seed yield in onion ranges from 300-350 kg/ha

42. Techniques of hybrid seed production- Cole
crops
Manifestaion of heterosis:
Heterosis in cabbage: 25-61%
Cauliflower: 20-60%
Broccoli: 26-58%
Manifested by head/curd size, early maturity,
head/curd weight and plant weight

43. Male Sterility and Hybrid SeedProduction
Cytoplasmic male sterile lines and their maintainers have
been developed in cauliflower, cabbage and broccoli using
radish cytoplasm for male sterility
Cytosterile plants of broccoli, cabbage and cauliflower are
petaloid with large nectarines responsible for bee attraction
and good female fertility
Seed Yield
It varies from500 - 800 kg/ha