Hybrid seed production of Tomato requires special skills and thorough details of the whole procedure.
In depth knowledge of all the steps, right from choice of species to be chosen as male and female parents till harvesting and packaging of F1 hybrid seeds is of great importance.
The workers should be trained enough to know the basic do's and don'ts during the process of emasculation, pollen collection and pollination (making crosses).
They should know about the factors responsible for seed admixtures and their prevention.
Selection of parents is the first and the foremost important step as the F1 hybrid so produce inherits its characters from parents only.
Both the parents should be necessarily pure lines and the female parent chosen should be better yielder that the male parent.
Parents should possess other desirable traits such as Earliness, synchronous maturity, good fruit quality, disease resistance etc.
Once the parents are selected, their seeds are sown in plots were the previous crop was not from Solanaceae family.
Male parental lines are sown 3 weeks earlier to that of the female lines to ensure the availability of pollen right at the beginning of the breeding operations.
Isolation distance of 50m is required between the two parental lines for pure seed production.
Male and female lines are planted at separate locations (at least 50m apart) and female plants are stacked to prevent fruit rotting.
Rouging i.
e.
removal of off-types is imperative at critical growth stages for obtaining true-to-type parental seeds.
Off-types are removed on the basis of plant, leaf and fruit characters.
Diseased plants are also removed as soon as observed.
Thus, quality of the hybrid seeds so produced depends upon rouging.
Steps of Hybridization 1.
Emasculation: Emasculation (removal of anthers from female flowers) begins about 55-65 days after sowing.
Flower buds from the second cluster which will open in 2-3 days are chosen for emasculation.
Only sterilized and sharp point forceps should be taken for carrying out emasculation.
The branch containing emasculated flowers should be tagged with a White thread so that they are easily located in the field.
Emasculation is done at previous day's evening before the day of pollination.
After the removal of anthers, emasculated flowers should be immediately covered with waxed paper bags.
2.
Collection of Pollen: Flowers from the male parents are collected to extract pollen.
The best time for pollen collection is during the early morning before the pollen has been shed (anther dehiscence).
Pollen collection should be avoided in rainy days.
3.
Pollination: Pollens should be gently placed on the stigma with the help of finger tip without destructing it.
Pollinated flowers should be covered with waxed paper bags.
Pollinated flowers should be tagged with a wax coated tag indicating the varietal name or code of Female and Male parents.
After the pollination is over, all non-crossed flowers on the female plants are removed to reduce the chance of contamination from selfed seeds before harvest.
Pollination is usually done 3 times weekly over a 3-5 week period.
Successful pollinations are noticed within one week in the form of fruit set and its enlargement.
Only tagged hybrid fruits should be retained on female plants and rest are removed.
This removal will prevent the accidental mixture of non-hybrid with hybrid fruits.
Furthermore, non-hybrid fruits will compete for water and nutrition from the ripening hybrid fruits.
Fully mature fruits at Red Ripe stage are harvested and kept in poly bags.
Only tagged hybrid fruits should be harvested to avoid the contamination.
During seed extraction, drying, packaging and storing, due care should be taken to avoid mechanical admixtures at all the stages.
Hybrid seeds should be labeled with Name of the Variety (of Male and Female Parent), Place of Harvest and date of harvest for easy identification.