Isolation distance
Since maize is a cross pollinated crop, it is necessary to isolate
seed field from maize crops of any other variety. The seed field must be
isolated at least by 200 metres for certified class seed from seed of other
varieties of maize.
Attention
You should not forget that by isolating the seed field from other
maize field, the genetic purity is maintained.
How to select the land?
Well drained sandy red or black cotton soil is suitable. The
selected field should be free of volunteer maize plants. Volunteer plants are
unwanted plant growing from seeds that have fallen from the plants of previous
maize crop. These plants may be of some other maize variety and cause genetic
contamination.
Field preparation
Plough the field five to six times to get fine tilth. Spread 12.5
tons of FYM ha-1 or composted coir pith and apply ten packets of Azospirillum
in the field. Prepare ridges and furrows with 45 cm spacing. Formation of
ridges and furrows enables saving of irrigation water.
Seed rate and seed treatment
For sowing one ha of certified seed field, 10 kg of foundations
seed is needed. To control seed borne pathogens of downy mildew (fungal disease)
treat the seed with carbendazim or thiram at 2g kg-1 seed. One day after seed
treatment with fungicide, treat the seeds with 600 g of Azospirillum with rice
gruel and shade dry for 15 minutes. Azosprillum treatments help in the fixation
of atmospheric nitrogen in the soil and provide nourishment to the growing
plants.
Sowing
Sow the seeds at 1/3rd of ridge from the bottom. Adopt a spacing of 10 cm from plant to plant and sow two seeds per hill.
Sow the seeds at 1/3rd of ridge from the bottom. Adopt a spacing of 10 cm from plant to plant and sow two seeds per hill.
Maize sowing
Irrigation
Immediately after sowing, irrigate the field. Then give life irrigation on third day and irrigate depending upon the condition of the field. Generally for maize, upto 30 days, less number of irrigation is given. Afterwards, it is necessary to irrigate once in 10 days. At this stage, the female cobs will be in silky stage. During this stage, if you fail to irrigate, the silk will not emerge from the cob, leading to poor pollination and seed setting and seed production is affected.
Immediately after sowing, irrigate the field. Then give life irrigation on third day and irrigate depending upon the condition of the field. Generally for maize, upto 30 days, less number of irrigation is given. Afterwards, it is necessary to irrigate once in 10 days. At this stage, the female cobs will be in silky stage. During this stage, if you fail to irrigate, the silk will not emerge from the cob, leading to poor pollination and seed setting and seed production is affected.
Fertilizer application
Apart from FYM applied before ploughing apply inorganic
fertilizers like 200 kg urea, 465 kg of super phosphate and 170 kg of potash
per ha as basal dose. Twenty days after sowing, apply 50 kg urea and at
40 days after sowing 110 kg urea and 45 kg potash as top dressing.
Maize seed crop
Micronutrient deficiency
Any nutrient deficiency in maize will adversely affect the growth
of the plant. Generally due to micronutrient deficiency, the yield is reduced.
Zn and Mg deficiency occurs largely in leaves. You can directly
seed the faded young shoot due Zn deficiency. And in between the veins of
mature leaves yellow lines are seen. To overcome these deficiencies apply ZnSO4
@ 20 kg ha-1 as basal fertilizer.
Mg deficiency will cause yellowish – symptoms between edges and
veins of basal leaves. The whole plant will have yellowish appearance due to Fe
deficiency. To over come the above deficiencies broadcast the micronutrient
mixture @ 62.5 ha-1 mixed with 40 kg sand, after sowing the seeds.
Attention
Observe the plants closely for micronutrient deficiency and apply the required micronutrients
Observe the plants closely for micronutrient deficiency and apply the required micronutrients
Weed management
Take two hand weedings on 25 and 45 days after sowing. After
weeding, apply fertilizer as top dressing and do the earthing up operation.
Herbicides can also be applied. Spraying of Atrazin 500 g mixed in 1000 lit
water and life irrigation on third day controls the weeds in maize fields.
Roguing
Generally roguing is done three times in maize. However, roguing is carried out depending upon the necessity. During roguing, off type and diseased plants are removed from the seed field. Roguing helps in maintaining the genetic purity of seeds. It is necessary to know the distinguishing features of the variety for effective roguing.
- First roguing should be done
during vegetative stage, based on the height of the plant, colour of
petiole and colour of leaf.
- During flowering stage, second
roguing is done based on colour of tassel and silk.
- Finally, before harvest, based
on colour of seed and cob characteristics, roguing can be done.
- During drying of the cobs,
roguing of cob based on seed colour and seed row will maintain the genetic
purity.
Attention
During roguing at flowering stage, the off types should be removed away from the field immediately. Otherwise it will contaminate the silk and affect the genetic purity.
During roguing at flowering stage, the off types should be removed away from the field immediately. Otherwise it will contaminate the silk and affect the genetic purity.
Plant protection
Insect control
Mix any of the granular insecticides with sand to make up a total
quantity of 50 kg and apply in the leaf whorls on the 20th day of sowing.
Quinalphos 5 G 15kg ha-1 and Carbaryl 4 G 20 kg ha-1 for the control of stem
borer, weevils and aphids.
If granular insecticides are not used, spray Quinalphos 25 EC 1
lit or Carbaryl 50 WP 1 kg ha-1 on the 20th day of sowing (500 litres of spray
fluid ha-1).
Disease control
- Downy mildew: Rougue out
affected plants. Spray Metalaxyl 72 WP @ 1 kg ha-1 or Mancozeb 1 kg ha-1
20 days after sowing.
- Leaf spot: Spray Mancozeb or
Captan 1 kg ha-1 when the disease intensity is high.
Harvest
Time of harvest
Time of harvest
Harvest the crop when the outer cover of the cob turns from green
to white colour. At the time of harvest, moisture content of the seed will be
around 25 per cent.
Maize cob ready for harvest
Cob sorting
It is an important operation in maize to maintain genetic purity.
Farm women can attend to this work efficiently. Remove very small sized cobs.
The cobs which show difference in seed rows and seed colour should be
identified and removed. The cobs with very less seeds also should be removed.
Cob sorting
Shelling
Seeds can be separated by mechanical means. For this operation, moisture content should be around 15 per cent for seed and 25 per cent for cob. By maintaining the moisture at this level, mechanical damage can be avoided. Seeds can also be separated from cob by beating with sticks. If the seeds are not in appropriate moisture content, occurrence of mechanical damage may occur to an extent of 48 per cent. Seeds with mechanical damage may invite fungal attack.
Seeds can be separated by mechanical means. For this operation, moisture content should be around 15 per cent for seed and 25 per cent for cob. By maintaining the moisture at this level, mechanical damage can be avoided. Seeds can also be separated from cob by beating with sticks. If the seeds are not in appropriate moisture content, occurrence of mechanical damage may occur to an extent of 48 per cent. Seeds with mechanical damage may invite fungal attack.
Husker sheller for maize
Seed drying
After shelling, dry the seeds. Mechanical seed driers can be used
for this purpose. During drying, air temperature should not go beyond 40°C.
Likewise avoid drying under the hot sun and the seeds can be dried in the
morning or evening hours under mild sun.
Seed grading
Quality seeds can be obtained by size grading the seeds with
18/64" round perforated sieves. Thereby you get good quality seeds of
uniform size.
Seed yield
Quality seed yield of 2500 kg ha-1 can be obtained.
Seed storage
Dry the seeds to 12% moisture content and treat with Captan or
Thiram 75 per cent wettable powder @ 70g per 100 kg seeds mixed in 500 ml of
water. Treated seed packed in cloth bag can be stored for more than one year.
Seeds dried upto 8 per cent moisture, treated with above chemicals and packed
in moisture vapour proof polyethylene bag can be stored for 1½ years. Instead
of toxic chemicals, you can also use nontoxic chemicals like halogen mixture
for seed treatment. This will reduce the environmental pollution and
ensures safety to the person engaged in seed treatment.
Seeds treated with halogen mixture @ 3 g kg-1 can also be stored
well. Prepare the halogen mixture by mixing bleaching powder (CaOCl2) + Calcium
Carbonate (CaCO3) + arappu leaf powder (Albizzia amara) in 5:4:1 ratio
and keeping in vapour proof jar for one week. Then use it for seed treatment.
Halogen mixture is nontoxic.
Maize seed packing in 700 guage polybag
Seed Certification
Field Standards (certified seed)
|
Factor
|
Maximum
permitted (%)
|
|
Off
types plants that have shed or shedding pollen when 5% or more than 5% of the
female flowers are in receptive stage.
|
0.20
|
|
Pure
seed (minimum)
|
98.0%
|
|
Inert
matter (maximum)
|
2.0%
|
|
Other
crop seeds (maximum)
|
5/kg
|
|
Other
distinguishable varieties based on kernel colour and texture (maximum)
|
5/kg
|
|
Weed
seeds
|
Nil
|
|
Germination
(minimum)-Inbreds
|
80%
|
|
Moisture
content (maximum)
Moisture pervious container |
12.0%
|
|
Moisture
vapour poof container
|
8.0%
|
QUALITY SEED PRODUCTION IN MAIZE HYBRIDS
Introduction
Even though the hybrid seed production methods are same as that of varieties, some additional techniques have to be followed. The hybrid seeds are produced by crossing female and male lines and harvesting the seeds from female line. Maize hybrid seed production there is no male sterility system in female plants. The female and male parents of few maize hybrids are:
Even though the hybrid seed production methods are same as that of varieties, some additional techniques have to be followed. The hybrid seeds are produced by crossing female and male lines and harvesting the seeds from female line. Maize hybrid seed production there is no male sterility system in female plants. The female and male parents of few maize hybrids are:
|
Hybrid
|
Female
|
Male
|
|
COH
(M) 4
|
(UMI
190 x UMI 1285)
|
UMI
112
|
|
COH
(M) 5
|
Single
cross hybrid of UMI 285
|
UMI
61
|
Attention
Rains during seed maturation phase will cause discolouration due to fungal attack thereby seed quality is reduced.
Rains during seed maturation phase will cause discolouration due to fungal attack thereby seed quality is reduced.
Isolation distance
Since maize is a cross pollinated crop, it is necessary to isolate
seed field from other maize fields. For this isolate the hybrid seed crop from
fields of other maize varieties with same seed colour by 200 m distance. And
for other varieties with different seed colour give 300 m isolation distance.
Land requirement
For maize hybrid seed production, well drained sandy red or black
cotton soil is suitable. The selected fields should be free from volunteer
maize plants.
Field preparation
Plough the field five to six times to get fine tilth. Spread 12.5
tons of FYM or composted coir pith and 10 packets of Azospirilluim in the
field. Prepare ridges and furrows with 60 cm spacing. Ridges and furrows enable
the saving of irrigation water.
Sowing operation
Seed rate
For one hectare 5 kg female and 2 kg male line seeds are needed.
Treat the seeds with Azospirillum biofertilizer as described for
varieties.
Seed treatment
To control seed borne pathogens of downy mildew (fungal disease)
treat the seed with carbendazim or thiram at 2g kg-1 seed. One day after seed
treatment with fungicide, treat the seeds with 600 g of Azospirillum with rice
gruel and shade dry for 15 minutes. Azosprillum treatments help in the fixation
of atmospheric nitrogen in the soil and provide nourishment to the growing
plants.
Sowing
Ridges and furrows at 60 cm spacing is to be formed. 2 seeds per hill on the sides of ridges adopting a spacing of 25 cm between the plant is sown. During sowing, a planting ratio of 4 female lines and 2 male lines (4:2) should be followed. Four female line rows should alternate with two male rows.
Ridges and furrows at 60 cm spacing is to be formed. 2 seeds per hill on the sides of ridges adopting a spacing of 25 cm between the plant is sown. During sowing, a planting ratio of 4 female lines and 2 male lines (4:2) should be followed. Four female line rows should alternate with two male rows.
Border rows
Sow three border rows all around the seeds field with male line
seeds.
Irrigation
Immediately after sowing, irrigate the field. Then given life irrigation on third day and provide subsequent irrigations depending upon the condition of the field. Generally for maize, upto 30 days, less irrigation is given. Then it is necessary to irrigate once in 10 days. Smooth silk will emerge out from the cob for fertilization. During this stage, you have to irrigate so that, the silk will come out smoothly from the cob and seed setting will occur.
Immediately after sowing, irrigate the field. Then given life irrigation on third day and provide subsequent irrigations depending upon the condition of the field. Generally for maize, upto 30 days, less irrigation is given. Then it is necessary to irrigate once in 10 days. Smooth silk will emerge out from the cob for fertilization. During this stage, you have to irrigate so that, the silk will come out smoothly from the cob and seed setting will occur.
Fertilizer application
Apply 25 tonnes of FYM per ha. Then apply inorganic fertilizers at
100 kg N, 100 kg P and 50 kg K per ha as basal dose. On 20th and 40th day after
sowing, apply 50 kg N and 25 kg P as top dressing.
Micronutrient deficiency
Any nutrient deficiency in maize will adversely affect the growth
of the plant. Generally due to micronutrient deficiency, the yield is reduced.
Zn and Mg deficiency occurs largely in leaves. You can directly
seed the faded young shoot due Zn deficiency. And in between the veins of
mature leaves yellow lines are seen. To overcome these deficiencies apply ZnSO4
@ 20 kg ha-1 as basal fertilizer.
Mg deficiency will cause yellowish – symptoms between edges and
veins of basal leaves. The whole plant will have yellowish appearance due to Fe
deficiency. To over come the above deficiencies you have to broadcast the
micronutrient mixture @ 62.5 ha-1 mixed with 40 kg sand, after sowing the
seeds.
Weed management
Take two hand weeding on 25 DAS and 45 days after sowing. After
weeding, apply fertilizers as top dressing and do the earthing up operation.
Herbicides can also be applied. Spraying of Atrazin 500 g mixed in 1000 lit
water and life irrigation on third day control the weeds.
Roguing
Rogue the off type plants as described for varieties. Do the rouging operation separately in female and male lines. Remove the male plants in female lines and female plants in male lines, plants of other varieties and off-type and diseased plants.
Rogue the off type plants as described for varieties. Do the rouging operation separately in female and male lines. Remove the male plants in female lines and female plants in male lines, plants of other varieties and off-type and diseased plants.
What is offtypes?
Plant or seed deviating significantly from the characteristics of
a variety as described by the breeder in any observed respect.
Attention
During roguing at flowering stage, the off types should be removed away from the field immediately. Otherwise it will contaminate the silk and affect the genetic purity.
During roguing at flowering stage, the off types should be removed away from the field immediately. Otherwise it will contaminate the silk and affect the genetic purity.
Plant protection
Insect control
Generally insect attack is very less in maize. In young plants,
only shoot fly affects the shoots. Stem borer affects the shoot on 25-30 days
after sowing. The affected shoots will dry and the sizes of the cob will be
reduced when the crop attains maturity. Therefore, it is necessary to apply
carbofuran granules @ 7.5 kg per acre @ 2 granules per plant.
Disease control
- Downy mildew: Rogue out affected plants. Spray Metalaxyl 72 WP
@ 1 kg ha-1, or Mancozeb 1 kg ha-1 20 days after sowing.
- Leaf spot: Spray Mancozeb or Captan 1 kg ha-1 when the
disease intensity is high.
Detasselling
Male inflorescence of maize plant is called tassel. Removal of tassels from female plants immediately after emergence is called detasselling. Detasselling should be continued for 14 days. It is done to enable crossing of female parent with male.
Male inflorescence of maize plant is called tassel. Removal of tassels from female plants immediately after emergence is called detasselling. Detasselling should be continued for 14 days. It is done to enable crossing of female parent with male.
Detasselling is done by holding the stalk with left hand, a little below the tassel, taking a firm hold of the entire with the right hand and removing tassel by a steady upward pull. Entire tassel should be removed without leaving any portion within the leaf. The removed tassels should be buried at the same place itself. Remove the tassels perfectly without damage to the leaves.
[Female flower (Cob) in Maize] [ Male flower (tassel) in Maize]
Detasselling technique
Attention
Removed tassels should not be left on the field they may also shed the pollen causing contamination.
Removed tassels should not be left on the field they may also shed the pollen causing contamination.
Harvest
Judge the optimum harvesting stage as that of varieties and harvest the male and female parental lines separately. First, the male lines should be harvested fully, after the removal of cobs of male lines from the field, the female lines should be harvested. The seeds harvested from the female line is the hybrid seed.
Judge the optimum harvesting stage as that of varieties and harvest the male and female parental lines separately. First, the male lines should be harvested fully, after the removal of cobs of male lines from the field, the female lines should be harvested. The seeds harvested from the female line is the hybrid seed.
Cob sorting
Remove very small sized cobs. The cobs which show difference in
seed rows, seed number and colour should be identified and removed. And the
cobs with very less seeds also should be removed.
Shelling
Seeds can be separated by mechanical means. For this, moisture content should be around 15% for seed and 25% for cob. After harvesting, cobs may be dried to the required moisture level before shelling. So that mechanical damage can be reduced. Seeds can also be separated from cob by beating with sticks. If the seeds are not shelled at correct moisture level, occurrence of mechanical damage may go upto 18 per cent, which will invite fungal attack.
Seeds can be separated by mechanical means. For this, moisture content should be around 15% for seed and 25% for cob. After harvesting, cobs may be dried to the required moisture level before shelling. So that mechanical damage can be reduced. Seeds can also be separated from cob by beating with sticks. If the seeds are not shelled at correct moisture level, occurrence of mechanical damage may go upto 18 per cent, which will invite fungal attack.
Seed drying
After shelling, dry the seeds, Seed drier can be used for drying.
During drying, air temperature should not go beyond 40°C. Likewise avoid drying
under hot sun and dry seeds during the morning or evening hours under mild sun.
Seed grading
Quality seed with uniform size can be obtained by size grading the
seeds with 18/64" round perforated sieves.
Seed yield
By adopting the above techniques, 1500 kg per ha of hybrid seed
can be harvested.
Seed storage
Dry the seeds to 12% moisture content and treat with Captain or
Thiram 75% wettable powder @ 70 g per 100 kg seeds mixed in 500 ml water.
Treated seeds packed in cloth bag can be stored for more than one year.
Seeds dried upto 8% moisture, treated with above chemicals and
packed in vapour poof polyethylene bag can be stored for 1½ years. As you have
learnt in the earlier lesson on varieties, seeds can be stored by treating with
halogen mixture also.
Seed certification
Seed certification guarantees the quality of seed as it ensures
that the certified seed has the genetic, physical, physiological and seed
health qualities. Genetic purity means that the seed gives rise to a
plant which conforms to the varietal characteristics of the variety. The
physical purity means that the seed is free from stones, broken seeds, straw
bits and leaf bits etc. Physiological quality is measured by germination and
seed health envisages freedom from pest and diseases.
Seed certification is being done in many stages. It starts from
verifying whether seeds were obtained from authenticated source, verification of
isolation distance and inspection during plant growth, flowering, harvesting,
processing and bagging. Also seed samples are drawn form the seed lot and sent
to seed testing lab to test whether the seeds are possessing required physical
purity and germination. Then certification tag is issued. Colour of the tag is
blue for certified seeds.
Only those seeds harvested from fields having prescribed field standards and possessing required seed standards are certified by the Certification Agency. Seeds thus certified are offered for sales. For further details nearer seed certification office may be contacted.
Only those seeds harvested from fields having prescribed field standards and possessing required seed standards are certified by the Certification Agency. Seeds thus certified are offered for sales. For further details nearer seed certification office may be contacted.
Field standards (Certified seed)
|
Factor
|
Maximum
permitted (%)
|
|
Off
types (%) maximum
Shedding tassel (% ) maximum |
0.5
1.0 |
Seed standards (Certified seed)
|
Factor
|
Maximum
permitted (%)
|
|
Physical
purity minimum
|
98.0%
|
|
Inert
matter maximum
|
2.0%
|
|
Other
crop seeds maximum
|
10.0/kg
|
|
Other
distinguishable varieties (maximum)
|
10.0/kg
(Number)
|
|
Weed
seeds basal on kernel colour and texture
|
Nil
|
|
Germination
(minimum)
|
90.0
|
|
Moisture
(%) (maximum)
For moisture vapour pervious |
12.0%
|
|
For
moixture vapour poof containers (maximum)
|
8.0%
|
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