Seed :: Vegetables :: Ashgourd

QUALITY SEED PRODUCTION IN ASHGOURD

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 selecte4d for seed production must not have been sown with ashguard in the previous season. This is done to avoid volunteer plants that cause admixture.

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.
        
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.

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 pollinated crop because flowering is monoeciuos in nature. Hence it requires 500 m (1500 feet) away from another variety of ashgourd.

Selection the right season for raising seed crop
        
Seed is very sensitive to whether. Hence selecting the right season is necessary. Though ashgourd can grow through out the year, seed crop should be grown such that the seed matures in cool dry climate. This will facilitate proper ripening of fruits and reduce the pest and disease infection. Seasons are selected with this idea in mind. In Tamil Nadu the best seed crop growing seasons are Aadi and Thai Pattam i.e. June – July and January – February.

Seed selection
         
Selecting ripe and vigorous seed is the first step in 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 must be taken to avoid the usage of aged seeds those are stored for more than a year.
          
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 chosen 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 for sowing has breeder seed tag (for producing foundations 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.

Preparation of main field and sowing
           
After proper ploughing, at a spacing of 2.5 x 2 m distance take pits having 45 cm length, width and height. Ten days after that, apply 10 kg FYM and urea 30 g. Super phosphate 72 g and potash 19 g per pit. Then mix the above nutrients with soil and fill the pits and level them.

Sowing
         
Seed required for an acre (400 g / acre) may be treated with fungicides before sowing. Then five seeds may be sown in a pit at equal distance.

Irrigation management
          
After sowing pits should be irrigated with water can. Care must be taken that the soil sho0lud not be eroded and seed should not be exposed. After the seedling emergence, field should be irrigated once in a week.

Main field maintenance     

  

Field care
       
Ten days after the germination, retain three vigorous seedlings per pit and remove two seedlings. So that it will facilitate for better growth of seedling without any competition between them.

Controlling weed
        
Maintaining the field from free of weed is more important for the crop growth. In ashgourd, one or two manual weeding is necessary before the flowering stage.

Growth regulator spray
          
Generally in curcurbitaceous vegetables, the male and female flowers borne separately. The number of female flowers decides the fruit yield. Hence, for ashguard, spraying of ethrel at 200 ppm for four times starting from four leaves stage and at weekly intervals (i.e. 2.0 ml of ethrel in 10 lit of water (is recommended. This facilitate for higher fruit yield.

Top dressing
         
Seed crop is entirely different from vegetable crop. Hence, fertilizer is also applied as split doses. Apply 22g urea/pit after 30 days after sowing as top dressing. This will facilitate the development and maturation of both fruit and seed. This leads to higher fruit bearing, higher fruit retention and quality seed yield.

Maintaining seed quality by rouging
    
One of the most important aspects of seed production is through rouging. Rogue is defined as the presence of those plants that deviates from the characters described for the variety. Such rogues if left in the field they tend to reduce the genetic purity of the seed crop ad thus reduce purchase value of resultant seed. Roguing is defined as the operation of removing rogues. In practice, all virus infected plants are to be removed.

When to do roguing
       
Roguing is more effective if done prior to flowering, since upon flowering there is very high possibility of cross pollination. Roguing is also attempted during vegetative phase, fruit formation stage and prior to harvest.

Roguing during vegetative phase
                    
During vegetative phase, during first 30-35 days, rouging is attempted based on plant characters like height of plant, leaf shape, size, surface of leaf. Plants showing heavy branching and spreading nature are removed. Plants showing variation in stem or leaf base colour are also removed. Those plants showing symptoms of yellow mosaic are also removed.

Roguing during fruit formation phase
       
At this phase, the rogues are removed based on fruit characteristics like length of fruit, size, shape and colour.

Roguing during fruit harvest phase
         
Roguing is done prior to harvest based on fruit colour and pests and disease infection. While harvesting the workers can be taught to separate infected fruits from good ones and forward only the uninfected fruits for seed extraction.

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

Harvest

Optimum stage of harvest
         
Harvest has to be done when the fruit stalk becomes brown and dried, and as the fruits have the complete ashy coating. At the stage the seeds attain full maturity will higher vigour and viability.
        
The harvests will be done in the different pickings in ashgourd. Here the first and last one or two harvests may be taken for vegetable. The harvest should be done from other harvests for seed extraction. Fruits confirming the genetic purity with medium to large size fruits should alone be used for seed extraction. This selection and grading procedures will increase the yield of quality seed recovery.
         
For seed purpose generally harvest will be done 7-10 days after the maturity of vegetables. Since, at that stage the seeds will attain its maturity. At that stage, fruit stalk become dry and there will be a complete ashy coating on the fruits.

Processing to improve seed quality
        
After the fruit harvest and before the seed extraction, only healthy fruits of true to type and free from pest / disease infestation are to be selected for seed extraction.

Seed extraction method

Seed separation by cutting the fruits
         
The selected fruits confirming the genetic characters alone should be used for seed extraction, and also fruits weighing less than 1.5 kg should be rejected and can be sold out in the market as vegetable. Seed extraction is easy in ashgourd. First cut the fruits into two halves by crosswise and length wise. Then remove the seed along with pulp and crash with hand in excess quantity of water. Remove the floating fraction and collect the seeds settle at the bottom.

Seed separation
        
Seed can also be extracted by acid method. Take the pulp along with seeds and Hydrochloric acid (diluted 6 times with water) at 1:1 ratio and allow it for 30 minutes with stirring. Because of this seeds will settle down. Then the floating fraction is to be removed. And then collect the seeds settled at the bottom and wash it with water for three or four times.

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

Seed drying
           
After seed extraction, it has to be properly dried, since seeds were extracted from 100% moist condition. The extracted seeds should 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 noon to 3 pm, since the rays emitted from sun and the heat may affect the seed viability. While drying care must be taken to avoid clogging.

The extracted seed should not be dried directly under sun. Since seed posses high moisture 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, fungal growth and poor vigour.

Seed cleaning and processing
       
After proper drying seeds have to be processed. By removing the ill filled and small size seeds, vigour and viability is improved. For processing ashgourd seeds, first white and dull yellow ill filled seeds are to be picked out manually.

Protecting seeds during storage
       
Producing quality seeds is only half of the job, the other half is protecting the seed during its storage that starts after processing till it is sown by the farmer. The major aspects that impart good storability are adequate seed moisture, seed treatment, mid-storage correction and seed storage container.

Seed moisture
       
Seed moisture is the foremost seed physical attribute that contributes for storage life. Lower he seed moisture, longer the shelf life. Short term storage can be achieved by drying the seeds to 6-7% moisture content while long term storage is possible by reducing the seed moisture even further to 6 %. Under such low moisture content, seeds have to be stored in moisture proof bags made thick polythene (700 guage).

Seed treatment
        
Prior to storage, seeds are treated with fungicide to ward off fungal pathogens. Seeds are mixed with Carbendazim 4g/kg. A novel technique called Halogen permeation treatment is also recommended in now-a-days. Calcium oxy-chloride, commercially know as bleaching power and powdered calcium carbonate (lime stone) is mixed in equal ratio. This mixture is added to seed at 5g / kg and stored.

Seed storage container
        
Apart from seed and seed treatment, the next most important aspect of seed storage is seed container. Container can be chiefly differentiated as moisture pervious and moisture impervious types. Cloth, paper, gunny bags are moisture pervious as the moisture from outside atmosphere can enter and exit freely. Hence, even if the seed is dried to safe moisture, but stored in a humid climate, then seed gains moisture during storage and looses vigour. So, to safely store seeds in moisture previous bag, then the outside humidity must be low.
         
In Tamil Nadu, most of the months are hot and humid, hence after drying the seed to safe moisture limit, seeds can be safely stored in moisture impervious bag like thick polythene bag of 700 g or in tin/plastic containers that are sealed tightly. In case of short term storage (4-6 months) cloth or gunny will be sufficient.

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 officer of your jurisdiction

Minimum seed certification standards prescribed for certified seed

Field standards

 

Rogues (maximum limit)

0.2%

Seed standards

 

Pure seeds (minimum limit)

98.0%

Inert matter (maximum limit)

2.0%

Other crop seed (maximum limit)

None

Weed seeds (maximum limit)

None

Germination (minimum limit)

60.0%

Moisture

 

Moisture proof bag

6.0%

Moisture pervious bag

7.0%

 
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