Hybrid Tomato Seeds Production

Full text

Hybrid Seeds Production
S.S.Janen
Project Manager – Seeds
Pacific Feeds Limited
National Youth Training Centre
Ministry of Youth and Sports, Fiji
11
th
March 2015

What is hybrid Vegetable seeds …………?
The offspring of two plants of
different species or varieties

Tomato Hybrid Seed Production
• Advantages compared to open-pollinated
varieties.
– High yielding.
– Early maturity
– Uniformity
– Better fruit quality
– Disease resistance
“Many farmers prefer to sow hybrid seeds in spite of
the higher seed costs”

Climate Requirement
• Ideal growing conditions are needed to
produce high quality seed.
• Tomatoes grow best in the dry season
• Day temperatures of 21-25°C
• Night temperatures of 15-20°C.
• Humidity levels higher than 60% at the time of
fruit maturity will increase disease problems
and reduce seed yields.
• Rainy season generally leads to low yields and
poor seed quality.

Field Requirements
• Avoid planting your tomato seed in the field of
solanaceous crops
– This will prevent the build-up of diseases and
insects.
• Optimum soil pH for tomato is 6.0 to 7.0
– Disorders such as blossom end rot are common if
soil pH is lower than 5.5.

Cultural Practices
• Healthy plants produce healthy seeds.
• Pests should be controlled.
• Nutrient and water management should be
optimal to achieve good fruit and seed yield.

Selecting Parents
• Hybrid seed production involves the crossing
of a female line to a male line.
• Both parents should be pure
• Preferably being self pollinated for more than six
generations (this is called inbreeding).
• The inbred parents are selected for their
desirable traits
» high yields,
» Disease resistance,
» Fruit quality,
» Earliness and etc.)

Ratio of Male to Female Plants
• It is important to have plenty of pollen
available for making hybrid crosses.
• Since tomato vines bloom excessively, a ratio
of one male for every four female (1:4) plants
is recommended.

Sowing Dates
• Seeds of male plants are sown three weeks
earlier to ensure that pollen is available from
the beginning of hybridization.

Isolation
• Each tomato flower has both male and female
parts
• Nearly all lines, including modern varieties, are self
pollinating.
• Isolation of male and female parental lines is not necessary.
• Male plants can be planted as close as two meters
from female plants.
• There are a few exceptions.
• Some lines are more attractive to insects and thus, more likely
to be cross-pollinated.
• Netting or caging to exclude pollinating insects is required if
any of these types are used as female lines.

Plant Location and Spacing
• Male lines are planted in a different location to
facilitate operations and avoid shading from
competing plants.
– Select a sunny spot to promote maximum production
of flowers and pollen.
• Male and female lines are planted in double-row
raised beds, with centers of beds spaced 150 cm
apart.
• Female lines: 70cm *50 cm
• Male lines: 70cm *40 cm

Staking
• The female parent is staked.
– facilitates the handling of plants during emasculation
and pollination
– keeps the ripening fruits above the ground and
prevents rotting
• Among male lines, only indeterminate types need
to be staked.

Removing Off-Types
• The male and female lines must be 100% pure
• Remove any off-type (usually inferior) or virus
infected plants before hybridization
procedures begin.

Emasculation
• Self-pollination cannot be allowed in hybrid
seed production.
• The female flower must be pollinated by the
pollen from the male line.
• To prevent self-pollination, remove the
stamens from the flower buds of the female
line before
• This process is called emasculation.

Emasculation Procedure
• Emasculation begins about 55-65 days after
sowing.
• Sterilize the forceps, scissors and hands by
dipping them in 95% alcohol before emasculation
is started.
• Use sharp-pointed forceps to force open the
selected buds.
• Then, split open the anther cone Carefully pull
the anther cone out of the bud, leaving the Sepal,
Petal and pistil
• To help identify the hybrid fruits from selfed fruits
at the time of harvest, cut the corolla and calyx
(all or two sepals)

Pollen Collection
• Collect flowers from the male parent to extract pollen
• The best time for pollen collection is during the early
morning before the pollen has been shed.
• Avoid pollen collection on rainy days.
• Remove the anther cones from the flowers and put
them in suitable containers, such as glassine,
cellophane, or paper bags
• Dry the anther cones by placing them 30 cm below a
100-watt lamp for 24 hours
• The lamp creates a drying temperature of about 30°C.
• Pollen can also be sun-dried, but avoid drying at
midday when temperature is very high.

Pollen Collection Con……
• Put the dried anther cones in a plastic pan or cup.
• Cover the cup with a fine mesh screen (200-300 mesh)
and then seal it with a similar tight-fitting cup, serving
as a lid
• Shake the cup about 10-20 times so that the pollen is
collected in the "lid" cup
• Transfer the pollen into a small convenient-to handle
container for pollination
• Fresh pollen is best for good fruit-set.
• It can be kept for one day at moderate room
temperature.

Pollination
• Emasculated flowers are generally pollinated two days later.
• Try to avoid pollination on rainy days.
• The corolla of the emasculated flower turns bright yellow,
signalling that the stigma is ready for pollination
• Dip the stigma into the pool of pollen in the pollen
container or pollinate by touching the stigma with the tip of
the index finger dipped in the pollen pool
• Pollination is usually done three times weekly over a three
to five week period.
• Successful pollinations are easily see within one week by
the enlargement of the fruit.
• After breeding operations are completed, any non-crossed
flowers on the female plants are removed to lessen the
chance of contamination from selfed seeds before harvest.

Fruit Production
• The number of hybrid fruits produced per plant
depends on the fruit size of the maternal parent.
• As a rule of thumb, maintain the following:
• 30 fruits for large-fruited parent;
• 40 fruits for medium-fruited parent; and
• 50 or more fruits for small-fruited parent.
• Hybrid fruits are easily recognized by their cut sepals
• Remove the naturally-pollinated (non-hybrid) fruits, if
any, from the female plants.
– This removal will prevent the accidental mixture of non-
hybrid with hybrid fruits.
– Furthermore, non-hybrid fruits will steal nutrition away
from the ripening hybrid fruits.

Harvesting
• Tomato fruits ripen about 50-60 days after
pollination, but may take longer if temperatures
are cool.
• Keep the fruits on the vine until they are fully
mature, preferably to the pink or red ripe stage.
• This enables the seed to develop normally and
fully.
• If fruits are harvested at an earlier stage, place them in a
covered, cool dry place for three or four days until they
become red ripe.
• Be sure to check for the clipped sepal before
harvesting fruit.

Seed Extraction
• Put ripe fruits into a mechanical seed
extractor for crushing and separation of the
seeds and gel from the pulp
• Gather the seeds and gel mass in a suitable
container such as plastic tub or bucket
• Instead of fermentation, treat the seed-gel
mass with hydrochloric acid (HCl)
• Stir the seed-gel mass while the acid is being
added. Continue stirring for 40 minutes until
the gel is visibly softened or dissolved.

• When the seed is separated from the gel, pour
the acid-treated seeds into a clean fine-mesh bag.
• Wash the bag with tap water thoroughly so that
no acid is left on the seeds’ surface
• Place the seeds into a plastic container, filling it to
one-third capacity.
• Then, fill up the container with tap water.
• Stir the seeds to enable the small pieces of flesh
and skin to float.
• Repeat the washing procedure several times until
all the debris is gone and the seeds are clean.

Seed Drying
• Placed the washed seeds in bags. Excess water
can be removed by hanging the seeds in the
shade for a day.
• An even quicker way to remove water is to place
the seeds in a spin
• Uniformly spread the partially dried seeds in a
flat plastic container or aluminium pan.
• Enclose this container with its seeds into a net
nylon bag.
• Place the container into an air drier
• These procedures will get the seeds to the
desired 6-8% moisture content.

Seed Packaging and Storage
• Pack and deliver the dried seeds according to
specifications of the seed company or contract
agency.
• If necessary, tomato seeds can be safely stored
for at least three to five years.
• Place seeds in manila envelopes, cloth or mesh
bags, plastic containers, or foil envelopes.
• The best containers are airtight, such as a sealed
glass jar, metal can, or foil envelope.
• If possible, the temperatures should not exceed
20°C and relative humidity (RH) in the storage
area should not exceed 30%.

THANK YOU
Make Fiji a Bountiful Island