Author: Panchal Bhakti B.
Department of vegetable Science,
ASPEE College of Horticulture and Forestry,
Navsari Agriculture University, Navsari- 396 450, Gujarat, India
• Seed separation from fruit is a specialized job.
• A slight negligence while extracting the seed can considerably damage its viability and vigour besides physical appearance.
• The in situ germination can also occur due to improper extraction technique.
• The seed can be separated by following methods.
(1) Acid Method
• In this method the fully ripened matured fruits are harvested and crushed to pulp.
• The pulp is taken in plastic container or wooden container or cement tub of convenient size and the commercial HCL added.
• The acid and pulp are mixed thoroughly and kept for as such time.
• During this period, corrosiveness of the acid removes the mucilage adhering to the seed and makes the seed free of pulp.
• Then, the seeds are washed 4-5 times thoroughly with water to make free of acid, otherwise the remanants of the acid spoils the embryo of the seed.
• The seed extraction is quicker in this method.
• Seed are also bright in colour with good germinability and free from fungal attack.
• The different extraction methods found that the seed recovery percentage was higher in acid method irrespective of varieties.
• Germination was highest in 2.5% HCL with 30 minutes soaking duration.
• Concentration of HCL was varies from vegetables to vegetables its taken in following table:
|Sr. no.||Crop name||HCL concentration||Time taken|
|1||Tomato||25 ml/1 kg of pulp||30 minutes|
|2||Brinjal||4 ml/1 kg of pulp 10 ml/1 kg of pulp 30 ml/1 kg of pulp||60 minutes 45 minutes 20 minutes|
|3||Water melon||1:6 (Acid: water ratio)||2 hour|
|4||Pumpkin||1:6 (Acid: water ratio)||5 minutes|
|5||Cucumber||100 cc/1 kg of pulp||30 minutes|
|6||Potato||10 ml/1 kg||20 minutes|
(2) Fermentation Method
• The fruits are crushed in a non-metalic container and kept as such for fermentation for 2-3 days.
• It has been observed that 2 days fermentation of fruits is the best for getting quality seed.
• During fermentation the seeds get detached from the adhering pulp and settles to the bottom of the container.
• The seeds are separated, washed thoroughly and dried under shade to the desired moisture level.
• The seed recovery is less compared to other method of extraction. The seeds become dull coloured due to fermentation of the pulp and also due to the fungal load in the seeds.
• In situ germination may occur due to long period of fermentation.
• These are method used in vegetables like, Tomato, Brinjal, Cucumber, Water melon, Musk melon, etc.
(3) Mechanical Seed Extraction
• This method is mainly used in vegetables like, Tomato, Brinjal and Chilli.
• In Tomato, the known weight of ripened tomato fruits is fed into the pulper machine. The pulp containing the seed is collected separately from the outlet, washed in water and then shade dried.
• In Brinjal, pulpers can also be used for crushing the fruits. Before using pulpers sufficient quantity of water is added and after pulping stirred well. Treatment combination of 2 mm concave clearance + 8.5 m/s cylinder peripheral speed + 1.76 of per hour feed rate produced the highest seed rate extraction (3.327 kg/hr) on extraction of seed with vegetable seed extractor.
• In chilli, dried chilli fruits fed through the feed hopper of seed extractor are subjected to the beating action and thereby the seed are separated and discharge through the outlet. The seed separated from hulls manually. The seed extraction efficiency was of as 96%.
(4) Alkali Method
• Fully ripened matured fruits are harvested and crushed to make pulp.
• In Tomato, to hasten the fermentation process 0.5% sodium bicarbonate (500 g dissolved in 10 l of warm water is added to the pulp and allowed to remain for a day.
• Then, the seeds are separated and washed free of alkali with water.
(5) Citric Acid Method
• In this method for seed extraction using 30 g of citric acid for one liter of pulp with digestion duration of 2 hour removes the gelatinous coating of seed without affecting the germination and vigour of seeds. But this method found to affect the storability of seed and used in only in tomato.
(6) Modified acid Method
• Freshly harvested fruits are pulped using water. The peals and pulp are removed leaving the wet seed with muscilage.
• Ten kilograms of fruit, yield 1 kg of wet seed. Forty ml of commercial HCL is added to this and allowed to react for 20 minutes with constant stirring.
• The seeds are then washed and dried. This method saves acid without affecting the seed recovery and seed quality.
• It's used in Tomato, Water melon and Musk melon.
(7) Dry Method
• The fully matured and dried fruits are harvested and dried in the sun for 2-3 days.
• After extraction of seed, the seed are dried in the sun between 8.00-11.00 Am and 2.00-5.00 Pm to bring out the original moisture content.
• Example like, Chilli, Okra, Sponge gourd, Ridge gourd, etc.
(8) Directly Harvesting of Matured Pod Method
• The pods are picked at maturity level and dried under sun for 2-3 days to reduce the pod moisture content to 15-16%
• Then the pods are beaten with pliable bamboo stick extract the seeds.
• Excessive drying and heavy beating should be avoided to reduce mechanical injury to the seed. Excessive mechanical injury results in lowering of seed quality.
• This method mainly used in Okra, French bean, Lablab bean, Cow pea, Cluster bean, etc.
(9) Manually Seed Extraction Method
• In which the fruits are cut into longitudinal bits and seeds are removed manually.
• Remanats of the pulp are washed and the seed are dried.
• This method also greatly influences seed storability.
• Example like, Water melon, Musk melon, Pumpkin and Bitter gourd.
(10) Floatation Method
• To separate the sinkers and floater, floatation technique is used. The immature seeds can be removed as floaters.
• Example like, Bottle gourd, and Other big seed vegetables.
(11) Wet Method
• This method of adopted for sweet pepper. The fruits are crushed and seeds are separated mechanically from remainder of the fruit pulp and debris.
• The crushed material is usually passed into a revolving cylindrical screen which allows separation of seed and debris.
Seed Curing of Vegetables
• The harvested crop is piled up in small heaps for curing either on a tarpaulin or cement floor and covered with a tarpaulin or hay to reduce rapid drying of branches.
• Curing with braches helps the unripened seed to ripen slowly, improves the colour of seed and also reduced shattering losses in the field.
• After 4-5 days the heap is turned upside down and allowed to cure for another 4-5 days.
• Care should be taken if the harvesting is done in wet humid period, the stock should not be kept as such for more than 4-5 days.
• This method is used in Cabbage and Cauliflower.
• In Potato, SPT method freshly harvested tubers are kept in a cool place under shade or in heaps at 1.5 meters height and 3.5 meters broad for 10 days to further cure the skin of tubers.
• Heaps are covered with paddy or wheat straw to protect from direct sunlight.
• If it rains, the heaps should be provided with tarpaulins.
• More time for curing may be required in heavy treatment soil as compared to sandy loam.
Seed Drying of Vegetables
• Seeds contain natural moisture, which at harvest time is often higher than the optimum required for the maximum potential life and best germination.
• The amount of moisture in the seed is probably the most important factor influencing the longevity and germination capacity of the seed.
• After the seed is detached from the mother plant, its moisture content is a function of relative humidity, and it is at equilibrium with that of the surrounding air.
• Seeds of fleshy fruits such as, Tomato, Cucumber and Melons, have much higher moisture content at harvest, and may absorb more water during their wet extraction process.
• On the contrary, seeds formed in fruits, which become desiccated during the ripening process, are relatively dry at the time of harvest, e.g. Onion, Amaranthus, Brassicas, etc.
• Under humid tropical conditions, the freshly harvested vegetable and flower seeds may have a moisture content ranging from 18 to 35% , which must be reduced to a 'safe level'.
1. H. Nemati, T. Nazdar, M. Azizi and H. Arouiee, 2010. The Effect of Seed Extraction Methods on Seed Quality of Two Cultivar's Tomato (Solanum lycopersicum L.). Pakistan Journal of Biological Sciences, 13: 814-820.
About Author / Additional Info:
I am the student of 2nd semester Ph. D. -Horticulture (Agriculture). Main subject of my research work on vegetables and fruit crops.