Seed Certification
Seed :: Vegetables :: Tomato

QUALITY SEED PRODUCTION IN TOMATO

Selection of land for quality seed production
        
The selection of land is the first and foremost task for a seed producer. The seed production plot must be selected carefully. A fertile and healthy seed plot will certainly produce quality seed. The field selected for seed production must not have been sown with tomato in the previous season. This is done to avoid volunteer plants that cause admixture. Fields continuously cultivated with tomato may harbour root rot to wilt pathogen. Hence, such fields must be avoided wherever possible. Following crop rotation will help to reduce endemic pathogen.
     
Soil with neutral pH must be selected. Loam or clay loam soils are best suited. Higher organic matter will lead to production of vigorous seed.

What are volunteers?
       
Volunteers are plants that grow in the field from the seeds found in the soil. These seeds should have been fallen from previous season crop. As they germinate without sowing or they volunteer to grow by themselves, hence the name volunteer plants.

Isolating the seed crop to avoid genetic contamination
       
The quality seed must be genetically and physically pure. Genetic purity can be maintained by preventing cross pollination with other undesirable varieties. This is achieved by isolating the seed crop.
       
Isolation is the act of growing the seed crop away from a contaminant such that cross pollination is prevented. Tomato seed crop must be grown 25 m away from another variety of tomato.
Selecting the right season for raising seed crop
       
Quality of seed also depends on the season in which it is grown. Even though tomato is almost grown all through the year, it more important to select suitable season for seed crop. In tomato, after the seed extraction, seeds should be dried under dry cool weather. Considering these factors, for tomato seed production June-September and December-March are the optimum season.

Producing quality seedlings for transplanting
       
Selecting ripe and vigorous seed is the first step of production of robust seedling which will ultimately lead to producing quality seed. Planting robust seedling will impart disease and pest resistance and help in proper uptake of precious fertilizer applied to the main field. Proper care at nursery stage will also help in early establishment and reduce the death rate in field, hence utmost care for producing robust seedlings is important.

Seed selection
       
Selection of seeds is the first step in production of quality seed. This involves selection of seeds with the right genetic make-up of the variety to be produced. Seeds must be from an approved source. This is possible if the seed is got from the breeding firm / university research station or from the breeder himself. Verify if the seed brought has breeder seed tag (for producing foundation seed); foundation seed tag (for production of certified seed). Further, the seeds must be free from pest and diseases; Rotten, dull coloured, black spotted seeds must be removed. Seeds of uniform size and shape alone must be used for sowing.

Nursery preparation and sowing
        
The area to be used as nursery must be under partial shade, preferably near water source. The soil must be healthy and fertile. A nursery area of 3 cents is necessary to raise seedlings for transplanting in one acre. The selected area is tilled two-three times followed by addition of one cart load of well decomposed compost. Raised beds of 1 m width and 3 m length are made. Small depressions are created using a stick (known as rills) at 10 cm intervals. Into these rills, about 150g seeds that are treated with 3 g Carbendazim are placed and covered using sand or dry soil.
Irrigated the nursery bed till it is completely submerged followed by irrigation once in two days.

Check this out
     
The maximum width of nursery must be 1m so that it facilitates weeding, plant protection and removal of dead plants.

Adding fertilizer to nursery
     
Fertilizer application is essential to provide robust growth to the emerging seedlings. Application of 2 kg DAP to the 3 cent nursery as basal is done which leads to prevention of root damage during pulling and earlier establishment of seedling upon transplanting in the main field. If DAP is not available, 6kg Urea and 12kg Super phosphate can be applied.

Age of seedling for transplanting
      
The right age of seedling is essential for better growth and development upon transplanting, if not planted in the right age then yield is reduced and seedlings are also susceptible for drought. Hence transplanting seedlings that are 25-30 days old is essential.

Main field preparation and management
        
Land selected for raising seed crop should be ploughed thoroughly for two (or) three times. At the last plough, per acre 20 tonnes of FYM has to be incorporated into the soil. There ridges and furrows are to be formed as detailed below depends on the varieties.

Varieties

Spacing between rows (cm)

CO1, CO3

60

PKM

75

CO2

80

Pusa ruby

80

Fertilizer application
         
After forming the ridges and furrows, the recommended doses of N, P and K fertilizers has to be applied on the 1/3rd height of ridges as a basal dose. Application of basal doses of fertilizers will be more important and support for the early vigourous growth of the seedlings. The basal fertilizer requirement per acre for tomato seed crop is as follows.
Urea: 66 kg, Super: 240 kg and Potash: 64 kg
.

Transplanting
     
 The healthy seedlings pull out from well maintained nursery has to be used for transplanting. After the irrigation i.e. complete soaking of ridges, single seedling should be transplanted as per the following spacing recommended for different varieties.

Varieties

Spacing between plants (cm)

CO1, PKM

60

CO2

75

Pusa ruby

70

CO3

30

Controlling weed
       
It is always essential to control the weeds early during the crop growth period as this saves labour and time. This can be done by applying weedicide Fluchloralin-400ml dissolved in 200 litre of water and sprayed using knapsack sprayer. The weedicide is applied on the third day prior to life irrigation. This will kill all the germinating weed seeds. If it is not possible to spray, then the recommended dose of weedicide (400 ml) is mixed with 20kg sand (4 iron chatties of sand) and spread uniformly on third day and the crop is life irrigated.
Weedicide will prevent emergence of dicot weeds for 15 days, after which the late emerging weeds can be controlled by hand weeding 40-45 days.

Earthing up
       
During the time of second weeding (45 days), the plants have grown to a height of 1.5-2.0 feet and are heavy. This leads to lodging, fruits formed on plants lying on ground tend to get infected by soil borne pathogens. Hence, after second weeding the plants are given an earthing up.

Top dressing
        
Seed crop is entirely different from vegetable crop and it needs more number of split application of fertilizers. For tomato, two split application of urea @ 33 kg/ acre
each at 40th and 60th day after transplanting is to be followed. On 40th day this will facilitate for more number of flowering and fruit set. Application of urea on 60th day will be useful for fruit as well as seed maturity.

Plant protection
        
Maintaining plant healthy is more important and hence prophylactic plant protection measure should be taken.

Fruit borer : To control fruit borer we have to follow any one of the following viz., spraying Quinalphos 25EC 250 ml/ac or carboryl wettable powder @ 2ml / liter of water or based on the ETL, Trichogramma, egg parasite may be released @ 20,000 /ac. at flowering stage.

Root knot nematode: Application of carbofuran granules @ 10 g/m2 at the time of planting.

Leaf curl virus: The virus is transmitted by white flies. To control the white flies spray methyl demeton or monocrotophos or dimethoate @ 200 ml/ac.

Roguing for seed quality maintenance
       
In the main field abnormal difference in growth habits in some of the plants are noticed and this shows the admixture of some other varieties. This may very much affect the genetic purity of that particular tomato seed crop and ultimately the crop will not be fit for a seed crop. Hence, in the tomato seed crop field removal of off type plants, weeds and virus infested plants is to be done scrupulously before it comes to flowering.

Disease infected plant

Rouging in different stages

Stages of rouging

Characters to be observed

Pre-flowering stage (or) vegetative stage

Plant height, number of branches, leaf and stem colour and pigmentation

Fruiting stage

Fruit shape, colour and size

After harvest fruit

Shape, colour and size

Caution!

All the rouges must be immediately removed from the seed field and destroyed.

Harvest
      
In tomato harvesting has to be done in 8 to 10 pickings. The first and last one or two harvests may be taken for vegetable purpose and the fruits from remaining pickings in between the above harvest may be used for seed extraction. The seeds from the above pickings are normally posses high vigour and germination. Well ripened fruits alone are to be harvested and medium to large size fruits may be used for seed extraction.

Processing to improve seed quality
        
After the harvest, the fruits not confirming to the varietal character, small fruits and pest and disease infested fruits must be removed and only graded fruits are to be need for seed extraction as shown in the photo.

Removal of small and diseased fruits

Seed extraction methods
       
The seed viability depends on the method on which the seeds were extracted and hence, it is more important to choose proper methods of seed extraction.
       
The acid method of seed extraction is the best method for tomato seed extraction. In this method, the fruits are to be crushed into pulp and taken in a plastic containers (or) cement tank and then add 10-20 ml of commercial Hydrochloric acid per kg of pulp, stir well and allow it for ½ hour. In between this duration the pulp may be stirred well for one or two times. This facilitates the separation of seed and pulp. After ½ hour, the seeds will settle down at the bottom and then add excess quantity of water and remove the floating pulp fraction. Afterwards collect the seeds settled at the bottom and wash with water for three or four times.
        
While following acid method we must use only plastic or stainless steel containers or cement tank, care must be taken to avoid the usage of iron (or) zinc containers, which will affect the viability potential of the seeds and as well damage to the containers due to chemical reaction with acid.
       
For large scale seed extraction we can use the tomato seed extractor fabricated and released by Tamil Nadu Agricultural University as shown in the photo. The seeds extracted by this machine may again be treated with commercial Hcl @ 2-3 ml/kg seed with equal volume of water for 3-5 minutes with constant stirring. And then seed should be washed with water for three to four times.

Tomato seed extractor

    
It is easy to dry the seeds extracted by acid method and also remove the fungus growth over the seed coat, thus seeds possess golden yellow colour and high vigour. The seed extracted by fermentation method posses poor vigour and off colour due to fungal activity.

Seed Drying
        
Immediately after seed extraction, it has to be properly dried, since seeds are extracted from 100% moist condition. The extracted seeds should be spread on gunny bags in a thin layer and dried under shade for 8 to 10 hours for one or two days. Then, seeds can be dried under direct sunlight between 8 to 12 noon and 3 to 5 pm. Avoid drying in between 12 to 3 pm, since the rays emit from sun and the heat may affect the seed viability.

 The extracted seed should not be dried directly under sun. Since seed posses highmoisture it may affect the germination potential. Similar, while drying frequent stirring is more important otherwise it leads to clogging. This may results in improper drying, fungus growth and poor vigour.

Seed cleaning and processing
       
After proper drying, the seed processing is essential. This will be helpful for maintaining high vigour and viability by way of removing immature and small seeds. In processing, we have to remove broken, immature and diseased seeds, other crop and weed seeds, mud and other inert matters. For processing tomato seeds, BSS 10 x 10 wire mesh sieve should be used.

Storage of unprocessed seeds results in poor viability. In processing, the sieves must be cleaned while changing to other variety otherwise it leads to physical admixture results in genetic contamination. Hence, utmost care must be taken during processing of seeds to maintain quality.

Moisture content
       
Seed quality mainly depends on the seed moisture. If seed moisture content is high normally it loses its viability at faster rate. For short term storage seed moisture content should be reduced to 7-8% and can be stored in cloth bag. For long term storage seed moisture content should be reduced to 6% and stored in moisture vapor proof containers.

Seed treatment
      
The seeds may be treated with captan or Thiram @ 4g/kg of seeds. The seeds can also be treated with halogen mixture @ 5g/kg of seed and it is a ecofriendly seed treatment.

Storage containers
       
Seeds could able to absorb moisture from atmosphere. Hence for storing seeds in the coastal region (or) river sides we should use moisture vapour proof containers i.e. 700 gauge polyethylene bags. For seed storage every time new containers must be used.

Seed certification
        
Seed certification will give guarantee for genetic purity and other qualities. It is a legally sanctioned system for quality seed production. The supply of improved varietal seed to the farmers with high genetic purity, physical purity and germinability are being the main objectives of the seed certification.
         
Seed certification acts at different stages from sowing to issue the tags and sealing the bags. They start their function by verifying the seed source before the seeds are sown, then verifying the isolation distance followed for that seed crop, taking field inspections at different stages viz., bagging operations. In addition to these operations, it is their duty to send samples to seed testing laboratory and after receiving the results, they will be issuing the certification tags.
         
The seeds so produced will be issued certification tag only after meeting out the prescribed field and seed standards.
Hence, by registering the seed production fields under seed certification we could able to produce genetically as well as physically pure seeds.
The private seed producers can also subject their seed production fields under seed certification for quality seed distribution.

For more details contact the seed certification officers nearby area.

Minimum certification standards

Field Standard

Off types

0.20%

Plants affected by seed borne diseases

0.50%

Seed standards

Pure seed (minimum)

98.0%

Inert matter (maximum)

2.0%

Other crop seeds (maximum)

10/kg

Weed seeds (Maximum)

None

Germination (minimum)

70%

Moisture previous containers (maximum)

8.0%

For vapour proof containers (maximum)

6.0%

 

 
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