Seed Production of Vegetable, Tuber and Spice Crops (2+1)

1. Genetic principles

• These principles highly depend on genetic characters of seed which can modify its performance in production programme. In seed production genetic characters are evaluated through genetic purity.
  
• Hence following principles are to be considered to obtain true to type seeds.
a. Seed production in adopted area
b. Approved seed source and generation system of seed multiplication

• Seed source should be from authenticated and approved public or private sector agencies. Always use higher class of seed for production of seeds. (eg. breeder for foundation and foundation for certified seed)
Generation system of seed multiplication

• Generation system of seed multiplication is nothing but the production of a particular class of seed from specific class of seed up to certified seed stage.
  
• The choice of a proper seed multiplication model is the key to further success of a seed programme.
  
• This is basically depends upon,
i. The rate of genetic deterioration
ii. Seed multiplication ratio and
iii. Total seed demand

• Based on these factors different seed multiplication models may be derived for each crop and the seed multiplication agency should decide how quickly the farmers can be supplied with the seed of newly released varieties, after the nucleus seed stock has been handed over to the concerned agency, so that it may replace the old varieties. In view of the basic factors, the chain of seed multiplication models could be,
(i). THREE Generation model :- Breeder seed - Foundation seed - Certified seed
(ii). FOUR Generation model Breeder seed :- Foundation seed (I) Foundation seed (II) –Certified seed
(iii). FIVE Generation model :- Breeder seed - Foundation seed (I) - Foundation seed (II) –Certified seed (I) - Certified seed (II)

Generation system of seed multiplication and quality control (notified varieties and hybrids)

Agency	Class of seed	Quality control system
Concerned breeder or Sponsoring institution breeding Breeder himself (no specified tag)	Nucleus seed	Maintenance
Concerned breeder or Sponsoring institution	Breeder seed (Golden yellow tag)	Breeder seed
State department of agrl	Foundation seed	State seed National Seeds corporation Certification seed Cooperative and Private sectors (White tag) Field inspection and Central and State seed testing to check minimum required standards of genetic, physical purity germination
Farmers	Certified Seed Truthful labeled seed	(Azhar blue tag) (Opal green)


• Three Generation model - (BS-FS-CS) - FOR CROSS POLLINATED CROPS
• Four Generation model - (BS-FSI-FS II-CS) - FOR SELF POLLINATED CROPS
c. Previous crop requirement

• This is very much required to avoid volunteer plants which can interrupt with genetic purity. Hence the land selected should not be grown with same crop of other varieties.
d. Prevention of natural crossing

• In sexually propagated crops natural crossing is another most important source of genetic contamination. This occurs due to crossing with undesirable plants, diseased plants and off types. This phenomenon is highly applicable to often and cross pollinated crops. The extend of genetic contamination in seed fields due to natural crossing depends upon the breeding system, isolation distance ,varietals mass, pollinating agent, insect activity, wind velocity ,humidity and temperature.
Table .1: Isolation distance required for the production of foundation and certified seeds of various crops

Sl. No.	Name of group (Crops)	Isolation in metres
		Foundation	Certified
1	Cole crops
	Cabbage	1600	1000
	Cauliflower	1600	1000
	Chinese cabbage	1600	1000
	Knol-khol	1600	1000
2	Fruit Vegetables
	Brinjal	200	100
	Capsicum (chillies)	400	200
	Tomato	50	25
	Okra	400	200
3	Bulbous vegetables
	Garlic	10	5
	Onion	1000	500
4	Root vegetables
	Beetroot	1600	800
	Carrot	1000	800
	Radish	1600	1000
	Turnip	1600	1000
5	Tuber vegetables
	Sweet potato	10	5
	Potato	10	5
6	Rhizomatous vegetables
	Ginger	10	5
	Turmeric	10	5
7	Legume vegetables
	Cluster bean	50	25
	Cowpea	50	25
	French bean	50	25
	Indian bean	50	25
	Lima bean	50	25
	Peas	10	5
8	Leafy vegetables
	Amaranths	400	200
	Beet leaf	1600	1000
	Coriander	800	400
	Fenugreek	50	25
	Lettuce	-	-
	Spinach	1600	1000
9	Cucurbits (All crops)	1000	500


e. Mechanical mixture

• Seeds should be physically pure ie., free from other crop seeds or other varieties of the same crop. It may often takes place at the time of sowing if more than one variety is sown with the same seed drill and also during post harvest handling of seed. Care on prevention is required as these will affect the genetic purity and also population maintenance.
f. Vigorous roughing

• Removal of unwanted, non true to type and diseased plants from the seed field is known as roughing. It should be done throughout the life cycle, but much care has to be given prior to the stage at which they could contaminate the seed crop.
g. Adoption of quality control system

• Seed must be produced only on adoption of generation system as recommended by Seeds Act 1966 to avoid genetic deterioration.