TIPS FOR VEGETABLE SEED PRODUCTION
The seed production programme envisages to produce genetically pure quality seeds and to store them in a viable condition for a reasonable period of time, until it reaches the farmers. The seeds should have genetic purity, uniformity in size and shape, high germination and vigour. The seeds should be free from mechanical damages, insect and fungal infestation and other crop and weed seeds. A commercial seed production programme has three aspects - seed production, seed processing and seed storage.
a. Seed production
The following aspects are important in this:
1. Basic knowledge on the specific requirement of the crop (climate, soil requirement etc.), specific characteristics of the variety, pests and diseases and their control measures are essential before taking up the seed production programme.
2. In general, September to January is the most suitable season for taking up seed production in Kerala.
3. Site selected for seed production should be open, receiving good sunlight, well drained and fertile soil, free from infectious pest and disease organisms.
4. Seeds for multiplication should be obtained from reliable sources.
5. Proper isolation distance should be maintained between varieties and related species.
6. Scientific roguing (removal of off-types at nursery stage, vegetative phase, flowering, fruiting and harvest stages) should be practised.
7. All plants infected by diseases should be removed from the seed production plot. No objectionable weeds are permitted in seed production plot.
8. In general, for most vegetable crops, taking one or two vegetable harvests is found ideal for economic seed production.
9. Provide one additional topdressing with N and K2O at fruit development phase, adequate irrigation and plant protection measures.
10. General cultivation and plant protection practices recommended for vegetable production can be adopted in seed crop also.
11. Harvest the crop at optimum fruit maturity, since immature and over mature fruits affect the seed quality.
b. Seed processing
1. Seed processing involves extraction of seeds from the fruits and reducing the seed moisture content to a level of 6-8%.
2. Wet and dry methods of seed extraction are adopted depending on the nature of the crop. Slow drying at low temperature (below 38ºC) is advisable rather than quick drying at high temperature.
3. Exposing seeds to open sunlight during peak hours of sunshine (12 noon to 3 p.m.) should be avoided.
4. Spread the seeds in thin layer and give frequent raking for aeration while drying to avoid fungal infestation.
5. Clean the seeds by removing inert matter, damaged and underdeveloped seeds etc. to get uniform quality seeds.
c. Seed storage
1. Store seeds under cool and dry conditions to maintain the viability
2. Seed moisture content of 6-8%, atmospheric temperature of 22ºC and relative humidity of 45% are the most ideal conditions for seed storage. The sum of storage temperature (ºC) and humidity (%) should not exceed 80.
3. Pre-storage seed treatment with fungicides (captan or thiram @ 2.5 g / kg of seeds) and insecticides (carbaryl 10% D @ 10 g/kg or lindane 5% D @ 20 g/kg) would protect the seeds from various fungal and insect infestations.
4. Store the treated seeds in 700 gauge polythene bags in sealed conditions.
Specific recommendations for seed production of the individual crops other than the general aspects mentioned above are given below:
The best time for planting tomato for seed production is October. Give an isolation distance of 50 m for foundation seed (FS) production and 25 m for certified seed (CS) between varieties. Rogue out off-types and virus infected plants. Maximum off-types and diseased plants permitted is 0.1% each only. Seeds should have a minimum purity of 98% and germination of 70%. Maximum permitted inert matter content is 2%, other crop seeds 0.1%, weed seeds 0.1%, and maximum moisture content 8%.
Give an isolation distance of 200 m for FS and 100 for CS. Remove off-types and plants infected by little leaf disease. No objectionable weeds are permitted in the seed production plot. Maximum level of off-types and plants infested by designated diseases are 0.1% each. Seeds should have a minimum purity of 98% and germination of 70%. Maximum inert matter content permitted is 2%, other crop seeds 0.1%, weed seeds 0.1% and maximum moisture content 8%.
Provide an isolation distance of 400 m for FS and 200 m for CS. Remove off-types and plants infected by virus diseases. No objectionable weeds are permitted in the seed production plot. Maximum level of off-types and plants infested by designated diseases are 0.1% each. Fruits of 45-50 days maturity may be harvested for seed extraction in the case of Jwalasakhi and Ujwala. Seeds should have a minimum purity of 98% and germination of 70%; maximum inert matter content permitted is 2%, other crop seeds 0.1%, weed seeds 0.1%; and maximum moisture content 8%.
Provide an isolation distance of 400 m for FS and 200 m for CS. Remove off-types and plants infected by yellow vein mosaic disease. No objectionable weeds are permitted in the seed production plot. Maximum level of off-types and plants infected by yellow vein mosaic is 0.1% each. It is economical to take two vegetable harvests and then retain the crop for seed production. Fruits of 36 days maturity may be harvested for seed extraction in the case of Arka Anamika. At this stage the pod colour completely turns to brown and tips dry. Seeds can be stored in polythene bags of 700 gauge thickness.
Seeds should have a minimum purity of 99% and germination of 65%. Maximum inert matter content permitted is 1%; no seeds of other crops or weeds are permitted; and maximum moisture content permitted for open storage is 10% and for storing in moisture proof containers is 8%.
An isolation distance of 800 m for FS and 400 m for CS is required between varieties and related species. Remove off-types, wild cucurbits and plants infected by designated diseases. No objectionable weeds are permitted in the seed production plot. Maximum level of off-types and plants infected by yellow vein mosaic diseases is 0.1% each. Seeds should have a minimum purity of 99% and germination of 60%. Maximum inert matter content permitted is 1%. No seeds of other crops or weeds are permitted and maximum moisture content should not exceed 7%.
Taking two vegetable harvests and then leaving the crop for seed production is economical. Ripe fruits of 24 days maturity in Preethi, when the whole fruits turn to bright orange colour, can be harvested for seed extraction. Seeds may be dried in the sun, avoiding peak sunshine hours of 12 noon to 3 p.m. Seeds can be stored in 700 gauge thick polythene bags.
Fruits can be harvested for seed extraction 36 days after anthesis (in TA 19), when yellowing of fruits start from the stylar end. Big and medium sized fruits (above 85 cm length and 2 kg weight in Kaumudi) give maximum quantity of quality seeds.
Oriental pickling melon
Harvest fully ripe fruits with deep orange colour (30 days after anthesis in Mudicode Local), when the vines wither. Select big and medium sized fruits (above 1.25 kg in Mudicode Local) for quality seeds.
Ash gourd fruits of 70 days maturity after anthesis are suitable for seed extraction. At this stage the vines wither; and the sticky thick ashy coating on the fruits dries into white powder, which can be removed on rubbing. Fruits of medium and large size (above 5 kg in KAU Local) give bolder, quality seeds. It is advisable to have a post-harvest storage of fruits for three months to get higher germination. Manual extraction of pulp from the fruits and fermenting the pulp for 48 hours is better to get quality seeds without mechanical damage. Pre-storage treatment of seeds with captan @ 2.5 g/kg and storing in sealed polythene bags of 700 gauge thickness is the best for seed storage.
Dried pods can be harvested for seed purpose. These pods are further dried in the sun before seed extraction. Good drying and pre-storage seed treatment of seeds (with carbaryl 10% D @ 10 g / kg seeds or lindane 5% D @ 20 g / kg seed and thiram or captan @ 2.5 g / kg seed) is essential to protect them from Bruchus and fungal infestations.
It is economical to take one vegetable harvest at 30 days after planting and then leaving the crop for seed production.