Quality of the seedling is on important factor related with production. Usually vegetable seeds are sown directly to the soil.
When you sow seeds directly to soil, seedlings will germinate and afterwards many will get rotten. This is mainly due to a soil borne fungal disease called Damping off.
When you ore using hybrid seeds which are very costly loosing one seedling will also count.
For getting healthy seedlings you can go for raising seedlings in pro trays. The benefit of using pro tray is that you will get healthy seedlings, will not loose even one seedling due to damping off and transplanting shock will be reduced.
The materials required are pro trays , Potting medium, 19:19:19 (water soluble fertilizer)
Pro trays with different to of cavities are available( like 98,50, 24 nos)
Potting medium can be prepared with coco peat , Vermiculite and perlite in the ratio 3:1:1.
Once the seedling reaches two leaf stage it can be sprayed with NPK fertlilizer 19:19:19 and can be repeated in every five days.
When the seedling reaches 4 leaf stage it can be transplanted to the main field or to the growbag/pot.
The benefit of growing seedlings in pro trays is that seedlings can be transported without any damage.