Most of thecucurbits are monoecious in character and a few are dioecious. A number of hermaphrodite and andromonoecious cultivars are also available in some crops. Pollination is largely done by insects. For pure seed production to separate it from fields of other varieties, fields of the same vareity not conforming to vareital purity requirements for certification.

Harvested for seed much in the same way that it is picked for the market. The fruit should not be left on the vine until decay begins.
Juice and Seed Extration: The canery equipment as pulpers and cyclones are primarily used, and after extraction the processers have in general two products: the juice and the pumice, or more or less the dry mass of squeezed pulp. skin and seeds. The only heat used may be scalding process to loosen the skin of the fruit. Such a mechanical method of seed extraction is rapid and leaves the seed practically free of seed extraction is rapid and leaves the seed practically free of the gelatinous tissue surrounding it in the fruit. Seed obtained by juice extracting equipment may be separated from the pumice by washing it with an abundant supply of water as described further on.
Ordinary seed extraction: When mechinery similar to that for vine crops is used, the chief difference is the lack of any heavy knives. The tomato is easily cut and crushed. It is usually made to pass between corrugated rollers before falling into a revolving wire mesh cylinder. the material and juice which passes through the screens is then poured into large tubes orvats where the extraction process is completed by one of the methods described below.
Separation by fermentation: The fermentation process is an old established procedure which effectively controls bacterial canker. It is best to allow the mass of fruit pulp and juice to ferment without theaddition ofwater. Fermentation should take place long enough forthe mucilaginous material adhering to the seed to distintegrate sufficiently so as to release the seeds, which sink tothe bottom. the undecomposed pulp floats to the top leaving a layer of clear liquid in between. Since, gas and floating pulp often entrap good seed and hold it in the upper layer, the contents of vats require fairly frequent stirring. Stirring tends to release such seed and also prevents fungus growth from starting at the survace of the mass.If thisfungus is allowed to grow, some discoloration and even injury to the seed may result.
Temperature determines to a large extent the length of time the fermentation process continues. If it reamins around 24 to 27 C most of the time, fermentation is rapid, and satisfactory separation of seed and pulp is attained in about two days. For thecontrol of canker, however, fermentationmust continue for at least 96 hours. Since such a long period may result in injury to the seed, it is advised that under such circumstances the fermenting pulp be kept as close to 21 C as possible. The lower thetemperature, the slower the fermentation process.
Acid separation: In the acid method, hydrochloric acid is added to the pulp at the rate 100ml forevery 14 kilogrammes of pulp (approximately 10 litres per tonne). If a thorough mixing of the acid and pulp occurs, the seeds may be washed free within 15 to 30 minutes. By proper arrangement ofequipment it is possible to have an almost continuous process.
The acid method has several advantages:
1. The seed can be extracted and dried on the same day.
2. Less number of vats are required.
3. The problems of low and high temperatures are avoided.
4. Discoloured seed resulting from fermentation is entirely eliminated.
To control bacterial canker theextracted seed, in addition, maybe treated with 0.8 per cent solution of pure acetic acid in water for24 hours, at temperature below 21 C.
Alkali separation: In alkali method equal volume of an alkali mixture (425 gm ordinary wahsing soda added to 5 litre of boiling water) is added to pulp and mixed. When the alkali mixture is cooled, allow it all tostand overnight in an earthen pot. Next day, all the seeds will settle down at the bottom ofthe container. Now decnt-off the clear liquid at the top and wash theseeds thoroughly.
Washing: After extraction the seeds are washed with water to remove the pulp, etc. The water is added to containers with the pulp and seed. It is stirred thoroughly and is drained out along with pulp and other mucilaginous substance. This process is repeated until the seeds are clean.
Drying: After washing, theseeds should be dried as rapidly as possible. Seed may be spread on screen bottom trays, or cloth, and placed in the open where a maximum exposure to sun and dry air is attained. The seeds should be dried to eight per cent moisture before storage.