HYBRID SEED PRODUCTION

INTRODUCTION

• Hybrid seed began with maize in the 1920s, and became extended to vegetables and flowers.

• Hybrid seeds are produced from naturally out-breeding crops, from which inbred lines are produced by repeated self-pollination.

• The established inbred lines are crossed to produce first generations (F1) hybrid seeds.

HYBRID SEEDHigher YieldsEarly MaturityUniformityBetter QualityDisease Resistance

TOMATO HYBRID SEED PRODUCTION

TOMATO• Tomato (Lycopersicon esculentum) belongs to the

family Solanaceae and genus Lycopersicon (2n-24)• It is usually grown as an annual for both fruit as well

as seed purposes. • Tomato is characterized by two types of plants :• (i) Determinate type-inflorescence occurs more

frequently in almost even internode until terminate ones are formed and elongation ceases at this point

• (ii) Indeterminate type-inflorescence cluster occurs at every third internode and the main axis continues growing indefinitely provided the growing conditions remain favorable.

Tomato is normally self-pollinated crop. Self-fertilization being favoured by the position of the receptive stigma within the cone of anthers and the normal pendant position of the flower.

Though the stigma is receptive at the time of anthesis, anthers do not dehisce until about 24-48 hours later.

Cross-pollination of tomato flowers to the extent of about 5 percent may occur through insects.

Seedling Raising• Tomato seedlings are raised in the nursery beds. • September-October is the optimum time for

sowing seeds in the nursery for crop production in the plains.

• For summer crop in the mountain areas the optimum time for raising seedlings is March/April depending on the altitude.

• Seeds are sown in line on a well-prepared seedbed and lightly covered with soil.

• After 7-10 days of sowing the young seedlings are transplanted on the second bed at a distance of 2-3 cm in both ways.

• The seedbeds should be irrigated immediately after transplanting.

• The seedlings should be protected from strong sun and heavy rains.

• Three hundred to three hundred fifty grams of urea dissolved in 30 liters of water can be sprinkled on nursery beds after about a week of transplanting the young seedlings in the second bed to get healthy seedlings.

• About 250-300g seed would provide sufficient seedlings to cover one hectare of land.

Training, Pruning and Staking

• Training of tomato plants with the help of wires or strings is claimed to result in early ripening, higher yield of better quality fruits and seeds, lesser disease incidence, easier intercultural operation and harvesting.

• Pruning side shoots and staking have claimed to have higher yield, uniform and larger fruits.

CLIMATE AND SOILCLIMATE AND SOIL• Ideal growing conditions are needed to

produce high quality seed. • DAY TEMP 21-25 *c , NIGHT TEMP 15-20

*c• Humidity is an important factor.

Humidity levels higher than 60% at the time of fruit maturity will increase disease problems

• Crop Rotation• pH

Soil and Climate• Tomato seed production is highly influenced by

environmental factor, particularly temperature which has significant effect on all stages of plant growth and development.

• Day and night temperature and the variation between the two has pronounced effect on growth, flowering, fruiting and yield of fruits and seeds in tomato, but the night temperature is a critical factor for fruit set in tomato.

• It is reported that plants could set fruits abundantly when the night *temperature is between 15°C and 20°C and the day temperature is about 25°C.

• Various experiments have revealed that temperature above 32°C leads to reduction in fruit-set. Fruit set is also reduced at a temperature below 15.5°C due to poor pollen dehiscence.

• Tomato can be grown on a rather wide range of soils from sandy to clay. The optimum soil pH is 6.5 to 8.0. To obtain good seed yield, fertile soil with efficient drainage and good water holding capacity should be selected.

Rotation• Tomatoes like brinjal crop are susceptible to

many of the soil borne diseases and therefore rotation must be taken into consideration to prevent pest and disease build-up.

• Generally a period of 3-4 years should elapse between successive tomato or brinjal crop.

Selecting Parents and Selecting Parents and SowingSowing

• F1 hybrid seed production involves the crossing of two different inbred lines

• EITHER MALE OR FEMALE, BEST YIELDER female.

• Both parents pure.• I male for 4 female plants• Early sowing of male plant

IsolationIsolation

• Isolation not necessary in Self pollinated crop.• As close as 2 m• Few Exceptions .

Isolation• The minimum isolation distance between

different cultivars of tomato for seed production is relatively short.

• This is because of the crop's high level of self-pollination. However, minimum recommended isolation distance between different varieties varies from 30 to 200 m in different countries.

Special Cultural Special Cultural PracticesPractices

• Healthy Plants produce healthy seeds

• Plant location and spacing• Staking and pruning• Female plant is staked for easy operations Removing of types, regular

inspection..

Emasculation

• Split open the anther cone.• Remove the anther cone out of the

bud• To help identify the hybrid fruits from

selfed fruits, cut few of the sepals.

Pollen Collection Pollen Collection •Extract pollen•Put flowers in envelops•Dry anthers

• Put in plastic cup with fine mesh screen (200-300mesh)• Shake the cup• Transfer Pollen in convenient-to-

-handle container

Pollination• When Corolla of the emasculated

flower turns bright yellow• Expose the stigma • Dip the stigma into the pool of

pollen• Pollination is usually done 3

times weekly 

Fruit ProductionFruit Production• maintain the following:• 30 fruits for large-fruited parent;• 40 fruits for medium-fruited parent; • and 50 or more fruits for small-fruited

parent.

• Remove non-hybrids from female plant

Fruit HarvestFruit Harvest• Tomato fruits ripen about 50-60 days after pollination, but may take longer if temperatures are cool. •Harvest when fruit is fully mature• Collect in non metallic containers….

Harvesting• Seed fruits are allowed to ripen to maturity

on the plant. • Only completely colored and matured seed

fruits are harvested. • The mark of the two sepals (calyx) cut off

should be checked carefully to ensure that only pollinated fruits are harvested.

Mechanical seed extractionMechanical seed extraction• Extract in nylon bags• Crush fruit by trampling with feet• Put them in tub for fermentation process

• Put water in open plastic container and stir.• Incline the container and remove the floating refuse• Repeat washing to get clean seeds

Mechanical seed Mechanical seed extractionextraction

• Put fruit in mechanical extractor• Instead of fermentation, treat the seed-gel mass with 0.7% hydrochloric acid (HCl) at a rate of seven milliliters

of HCl per kilogram of seed-gel mass • Pour seeds on mesh and wash them

Seed DryingSeed Drying• Use mesh bags and hang them in

open air• Or• Spin dry them in a washing

machine • Spread seeds in a container and

put them in seed dryer for 3-4 days at 30 *C

Storage and packagingStorage and packaging• Pack according to specifications

seeds company or contract agency.• Note the names of the hybrid and

parents, the year, and any other information.• Carefully label each container• Store in cool dry place 20*C• R.H 30 %

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