CERTIFIED SEED PRODUCTION OF SELECTED CROPS
Seed
production practices vary to a great extent from one crop to another. The
precautions necessary during seed production are largely affected by the
natural mode of pollination in the crop species. In self-pollinated crops,
fewer precautions are required than are in cross pollinated and often cross
pollinated crops. It must be remembered that certified seed of only such
varieties can be produced that have been released by either the Central or
State Variety Release Committee and notified by the Ministry of Agriculture and
Cooperation, Government of India.
SELF-POLLINATED CROPS
Seed
production in self-pollinated crops, such as Rice, Wheat, Barley, Oat, most
of the pulses and certain oilseeds is easy because there is very little
outcrossing (less than 5%). The chief concern in seed production of these crops
is to prevent mechanical mixtures; this is done by isolating the seed crop from
other crops by a distance of 3m, and by roguing the off-type plants from the
seed crop. Cultivation of the seed crop is essentially similar to that of the
commercial crop as below:-
1)
Land
Requirement:- There are no specific land
requirements, but it should be suitable for cultivation of the crop.
2)
Isolation:-
Isolation of 3m must be provided on each side of the seed field to prevent
mechanical mixtures and chance outcrossing.
3)
Cultural
Practices:- For each crop, a standard package of
cultural practices is available, which should be strictly followed. If not done,
there may be reduction in yield and seed size which would reduce the income to
the seed growers.
4)
Plant
Protection:- Recommended plant protection measures
must be followed to protect the crop against diseases and insect pests. Seed
borne diseases like loose smut of wheat must be controlled because the presence
of diseased plants may lead to rejection of the seed crop.
5)
Weeding:-
The seed crop is required to be free from weeds, particularly from
objectionable weeds. The presence of objectionable weeds would lead to the
rejection of seed crop.
6)
Roguing:-
Off-type plants must be rogued, this is essential to avoid mechanical mixture
and chance outcrossing. There is a maximum permissible limit for the presence
of off-type plants during any field inspection. Diseased plants are removed and
destroyed.
HYBRID MAIZE (Zea mays)
Seed producers are
supplied with the foundation seed of the female or seed parent and the male
parent or pollen parent. The female and male parents are supplied at the rate
of 45,000 and 15,000 seeds per hectare, respectively.
1)
Isolation:-
The
minimum isolation distance is 200m; it can be modified by planting border rows
of the pollinating parent. Different planting dates may be used to modify
isolation distance provided there is no receptive silks in the seed parent at
the time of pollen shed in the contaminating field.
2)
Cultural
Practices:- A standard package of cultural practices
is available, which must be strictly followed to raise a good healthy seed
crop. Recommended doses of fertilizer must be applied and inter cultural
operations must be done to remove weeds.
3)
Planting:-The
recommended planting ratio is 2 male rows to every 6 rows of the female parent.
The male rows should be marked at both the ends with flags, pegs or marker
plants like sunhemp. At least one border row of the pollinator parent should be
provided on each side of the field to ensure pollination at the edges of the
field. The spacing should be 75-90cm between rows and 20-25cm between plants.
4)
Plant
Protection:- Maize crop has to be protected against
insect pests, such as stem borers, hairy caterpillars, army-worms,
grass-hoppers, maize beetle and white ants.
5) Detasseling:- Removal of tassel, the male
inflorescence, before it has shed pollen is known as Detasseling. If the female
parent is male fertile, Detasseling must be done to avoid self-pollination in
the seed parent. Detasseling is done by holding the plant with left hand a
little below the tassel, grasping the full tassel in the right hand and
removing the tassel by a upward pull. The tassel is then thrown on the ground.
In most cases, the tassel is removed one or two days after the tassel is first
visible, but in some cases it may have to be removed before emerges. Care must
be taken to remove the entire tassel. Detasseling is done regularly everyday as
long as tassels emerge on the female parent plants. Two field inspections would
be made during the pollination period to determine the percentage of female
plants that shed pollen and very rigid standards is maintained.
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6)
Roguing:-
Off-type
plants are removed before they shed pollen. There are rigid requirements with
respect to the presence of off type plants during field inspections.
7)
Harvesting:-
Male
rows are harvested before the female rows and the produce is removed from the
field in order to avoid mixture with the harvest from female rows.
8)
Drying:-
At
the time of harvesting, seeds have 30-32% moisture. Therefore the cobs are
dried in drying bins to reduce seed moisture to 12%. The grains are then
shelled, cleaned and graded before treating and bagging.
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