Seed Production of Vegetable, Tuber and Spice Crops

Method of seed production

Land Requirements

• There are no land requirements as to previous crop, but the land should be free of volunteer plants. Generally the soil should be well drained and aerated.
Isolation Requirements

• Most of the cucurbits 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 maintain isolation distance all around seed field is necessary to separate it from fields of other varieties, fields of the same variety not conforming to varietal purity requirements for certification, from wild cucurbit species, and to separate musk melon from long melon and vice versa, and pumpkin from summer and winter squashes and vice versa as follows


Class	Minimum distance (meters)
Foundation	1000
Certified	500


Hybrid seed production

• In cucurbits, the presence of heterotic combinations, flower size and colour, pollen production capacity of male plant and longer duration of stigma receptivity, easiness in emasculation and pollination, attraction of insect as a means of pollen transfer, seed setting and their economic feasibility in production as well as adoption supports the production of F1 hybrid seed.
Picking of male flowers and artificial pollination

• In monoecious plants, emasculation is not required. Female and pollen parent lines are planted alternately in an isolated field. The male flowers from the female parent are pinched before they open. Pistillate flowers of the female parent are artificially pollinated with the pollen of the male parent using cotton puffs by manual labour.
Picking of male flowers and insect pollination

• Female and pollen parent lines are planted alternately in an isolated field. The male flowers from the female parent are pinched before they open. Female flowers are left on the seed parent and allowed to be pollinated by insects from the pollen parent.
Use of gynoecious lines

• The gynoecious (female parent) and monoecious (pollen parent) lines are planted alternately. Since the percentage of gynoecisous plants in different gynomonoecious lines is variable, all the monoecious plants are removed at the early stage. Seed is collected only from gynoecious plants that have been left for seed production.
Maintenance of gynoecious lines

• In gynoecious lines, only pistillate flowers are produced and so it requires staminate flowers for self pollination. For production of staminate flowers, GA-3 100ppm is sprayed thrice at 15 days interval from 2nd leaf stage or single foliar spray of silver nitrate 600ppm is done before 1st flower open. It induces staminate flowers for fertilization of pistillate flowers. At physiological maturity / ripening, fruits are harvested and seeds are extracted. Such seed when sown in next generation will produce only pistillate flower.
Use of genetic male sterility system

• Genetic male sterility system has been utilized for commercial hybrid seed production. Since genetic male sterile line is maintained heterozygous forms, 50% fertile plants are to be removed at flowering. The other 50% having non-dehiscent empty anther are retained in female rows. The female and male are grown in 4:1 ratio. However, to maintain the good plant population in female rows, it is suggested that seed parent should be sown with double seed rate. It is also advised that female line seedling should be raised in polythene bags and transplanted at flower appearance in order to avoid the fertile plants in female rows. The pollination is done by honey bees and 1 to 2 medium sized hives are good enough to ensure the good pollination and fruit set at female rows.