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Maize Varieties and Quality Seeds

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Maize Varieties and Quality Seeds

Dr. Bhagya Rani Banik

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Importance of  maizeImportance of  maize1.1. HIGH YIELDHIGH YIELD

2.2. Year round productionYear round production

3.3. C4 crop, the crop of global warmingC4 crop, the crop of global warming

4.4. Less disease and pestsLess disease and pests

5.5. Versatile use;Versatile use;1. Food (flour, flakes, soup)

2. Feed (poultry, dairy, fish)

3. Baby corn, green corn, pop corn

4. Starch, oil5. Fodder, fuel

6. Green manure

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Maize Area, Production and Yield in Bangladesh

0.00

500.00

1000.00

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1   9   8   9   -  9   0   

1   9   8   9   -  9   1   

1   9   9   1   -  9   2   

1   9   9   1   -  9   3   

1   9   9   3   -  9   4   

1   9   9   3   -  9   5   

1   9   9   5   -  9   6   

1   9   9   5   -  9   7    

1   9   9   7    -  9   8   

1   9   9   7    -  9   9   

1   9   9   9   -  0   0   

1   9   9   9   -  0   1   

2   0   0   1   -  0   2   

2   0   0   1   -  0   3   

2   0   0   3   -  0   4   

2   0   0   4   -  0   5   

2   0   0   5   -  0   6   

2   0   0   6   -  0   7    

2   0   0   7    -  0   8   

2   0   0   8   -  0   9   

2   0   0   9   -  1   0   

 Year 

   A   r   e   a

   (   0   0   0   h   a   )   a   n   d

   P   r   o   d   u   c   t   i   o   n

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   Y   i   e   l   d

   (   t   o   n   h   a

  -   1   )

 Area (000 ha)

Production (000) ton

Yield (t/ha)

Fig 1. Area, production and grain yield of maize in Bangladesh (1990-2010)

Source: BBS and DAE, 2010

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Table 3. Production target in 2010, 2015, 2020, 2030 and 2050

(as far as available)

Projected population/

Demand/ Production

target of maize

Projected Year

2010 2015 2020 2030

Projected pop. (mil.) 148.0 156.7 166.9 190.6

Demand (mil. ton) 1.88 2.25 3.00 3.50

Target area (m ha) 0.20 0.30 0.35 0.40

Target avg. yield (t/ha) 6.5 7.5 8.0 8.5Prodn, target (mil. ton) 1.30 2.25 2.80 2.97

Source: BBS andMoA

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Farmers field, ComillaFarmers field, Comilla (22 May 2009)(22 May 2009)

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Reasons for popularityReasons for popularity::

1. High grain yield

2. Two cropping seasons per year

3. Flexibility in planting time4. Fits well in cropping pattern

5. Low risk of complete crop damage

6. Can be used as fresh, boiled, dried & fried

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ProblemsProblems

1. Pollination control2. Inbreeding depression

3. Maintenance of inbred lines

4. Maintenance of hybrid variety ?

5. Short viability of seed

6. Shelling

7. Drying

8. Milling9. Eating

10. Selling

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ProblemsProblems

1. Pollination control2. Inbreeding depression

3. Maintenance of inbred lines

4. Maintenance of hybrid variety ?

5. Short viability of seed

6. Shelling

7. Drying

8. Milling9. Eating

10. Selling

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VarietyVariety developmentdevelopment

1. Composite/Synthetic/OP

2. Hybrid: Single, 3-way, double cross

3. Top cross/Double top cross hybrid

4. Sweet corn

5. Pop corn

6. Baby corn (vegetable)

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Classification

�Dent maize

�Flint maize

�Sweet corn

�Flour corn

�Pop corn

�Pod maize

�Waxy maize

� Baby corn

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List of composite maize varieties developed by BARI

Variety Yield (t/ha) Year of 

release

Suitable area

1. Barnali 4.0-5.0 t/ha 1986T

he crop can be cultivated all over Bangladesh

2. Shuvra 4.5-5.5 t/ha 1986 The crop can be cultivated all over Bangladesh

3.Mohar 4.5-5.6 t/ha 1986 The crop can be cultivated all over Bangladesh

4. BARIMaize 5 5.5-6.0 t/ha 1997 The crop can be cultivated all over Bangladesh

5. BARIMaize 6 5.7-6.2 t/ha 1998 The crop can be cultivated all over Bangladesh

6. BARIMaize 7 5.5-6.5 t/ha 1998 The crop can be cultivated all over Bangladesh

7. Khoibhutta 4.5-5.0 t/ha 1986 The crop can be cultivated all over Bangladesh

8. BARI Sweet corn 1 10-10.5 t/ha 2002 Homestead areas

Achievement of maize improvement at BARI

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Achievement of BARI

List of hybrid maize varieties developed during 2000-2010

Hybrid Variety Yield

(t/ha)

Maturity Year of 

release

Grain colour and texture

BARI hybrid maize 1 7.5 - 8.5 140-145 2000 Orange-yellow, flint

BARI hybrid maize 2 8.0 -9.0 138-142 2002 Orange-yellow, semi-flint

BARI hybrid maize 3 9.0 -9.5 144-150 2002 Yellow, dentBARI hybrid maize 4 7.5 - 8.5 142-146 2002 Orange-yellow, flint

BARI hybrid maize 5 9.0 - 10.0 140-145 2004 Orange-yellow, flint

BARI hybrid maize 6 9.8 - 10.0 141-145 2006 Yellow, flint

BARI hybrid maize 7 10.5-11.2 141-145 2006 Yellow, flint

BARI hybrid maize 8 9.7 -11.5 142-146 2007 Yellow, dent

BARI hybrid maize 9 10.2 -12.0 145-150 2007 Orange-yellow, dent

BARI hybrid maize 10 9.0 -11.5 145-150 2008 Yellow, flint

BARI hybrid maize 11 9.5 -11.5 147-153 2008 Yellow, flint

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Dent maize

Flint maize

Flint and Dent Maize

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Dehusked Sweet CornSweet cob corn with husk

Sweet corn

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Mature pop corn Popped corn

Pop corn

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Baby corn with husk

Baby corn without husk

Baby corn to harvest

Baby Corn

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Estimation of heterosis

� Mid parent heterosis %

= F1-Mean of parents (MP)--------------------------------------X 100Mean of parents (MP)

� Heterobeltiosis %

F1-Mean of better parent (BP)

--------------------------------------X 100

Mean of better parents

� Standard heterosis %

F1-Mean of standard check 

--------------------------------------X 100

Standard check 

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Concept of hybrid maize

development

Source materials� Development and evaluation

of parent materials

� Development of hybrids

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Development and evaluation of 

parent materials

� By enforced selfing followed by

selection

� Sibbing whenever necessity will

arise

� Evaluation by combining ability

test

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� Ter minology related to hybrid technology

� Inbred line : A nearly homozygous line developed by

continued inbreeding, usually self ing,accompanied by selection.

� Inbreeding : Mating between individuals related by descent or 

ancestry.

� Inbreeding Depression : Loss in vigour due to inbreeding.

� Heter osis : Superiority of  F1over the parents (or even

inf eriority to both the parents).

� Hybrid Vigour : Synonymous to Heter osis.

� Hybrid : Pr ogeny f r om hybridization between two or more strains.

� Hybrid variety : A hybrid variety is the F1 generation f r om a

cr oss between two diff erent strains.

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Types of hybridsTypes of hybrids

� a) Single cr oss: A single cross hybrid is the product of a cross

between two unrelated inbreds.

� Seed parent X Pollen parent

(Inbred  A) (Inbred B)

� Single cross ( AB)

� b) Modif ied single cr oss : A modified single cross is a

cross of the type ( A x  A1) X C where  A and  A1 are sister lines.

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� c) Three way cr oss :  A Threeway cross hybrid is produced

by crossing a single cross and another unrelated inbred

� Seed parent X Pollen parent

�(Single cross

 AB) (Inbred C)

� Threeway way cross

� ( ABC)

� d) Double cr oss : A double cross hybrid involves 4 unrelated

inbreds.  At first two single crosses are produced. The two single

crosses are mated to produce the double cross.

� Seed parent X Pollen parent

� (Single cross  AB) (Single cross CD)

� Double cross

� ( ABCD)

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� Sequential steps in hybrid seed pr oduction

� Commercial hybrid maize seed production broadly involvethe following steps :

� 1. Maintenance and breeder¶s seed production of the parental lines

� 2. Multiplication/production of breeders seed, foundation seed

certified seed

� 3. Production of hybrid seed i.e. single cross, threeway cross anddouble cross

� 4.Processing of the hybrid seed

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eren ec n ques n y r seeeren ec n ques n y r see

pr oduction of  maizepr oduction of  maize

Site selectionSite selection

Land typeLand typeIsolated f ield requirementIsolated f ield requirement

Table 1. Showing number of  isolated plots/f ields necessary for diff erentTable 1. Showing number of  isolated plots/f ields necessary for diff erent

types of conventional hybridstypes of conventional hybridsTypes of hybrid Inbred

 parents

SC

 parent

Hybrid Total

Single cross 2 - 1 3

Three-way cross 3 1 1 5

Double cross 4 2 1 7

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� Time of sowing� Plant population densities

� Avoiding mixtures of  males and

f emales� Female : Male ratios

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IsolationIsolation

1. Isolation Distance - The greatest contamination occurs within 50 to 75 m

of the contaminating source. Minimum isolation

distances for hybrid maize as foundation and

certified seeds are 400 m and 200 m, respectively

- Certainly, the greater the distance and number of male border rows, the less chance of contaminate pollen

entering in the field.

2. Time Isolation - Using time isolation, it is best to have a minimum of 

25 days to one month difference between the

 planting of seed crop and potential contaminatesources. This time may slightly vary with different

varieties.

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� Techniques applied for synchr onization

of  f lowering*Delayed planting

*Double planting of male rows

*Clipping or mowing - It is effectively used to save a maize

crop when inclement weather occurred after the first

parent was planted but before the second parent was

sown. It is best to mow when plants are about 25 to30cm tall, cutting away half of the plant material.

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Table 2. Showing the amount of delay based on different treatment times

Treatment Delay in flowering*

20 cm cutback to 10 cm 4 days

60 cm cutback to 30 cm 7 days

90 cm cutback to 45 cm 7 days

Proc. of the Third  Ann. Seed Tech. Conf., Iowa State University, 1980.

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� Impr oving pollendistribution and seed set

� Collect pollen f r om male r ows and

hand pollinate

� Physically shake male lines.

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� Roguing

� There are three basic types of 

rogues

� Volunteer corn : These are corn plants grown in the

field from previous year outside the production field but

within the isolation limit.

� Off types:  Any corn plants in the seed production field

other than the designated parents.

� Plants out of place : Females in male rows and

vice versa. Some plants may be displaced during

irrigation and other cultural operation.

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� Two types of contamination can

occur in the field 

� Genetic contamination - Caused by cross-

pollination with other maize plants growing in the

field or in the isolation area. It can also be causedby accidental self-pollination of female parents of 

hybrids due to improper detasseling.

� Mechanical contamination - Caused by mixing

seed or transplanting of undesirable plants

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WhenWhen toto roguerogueRoguingRoguing shouldshould bebe donedone duringduring thethe followingfollowing stagesstages of of plantplant growthgrowth ::

Post emergence

: Rogue off-type plants that are often

easily identified due to their  

difference in size and their position

out of the rows.

Vegetative

development

: Rogue off-type plants, which differ 

from the given genotypes in respectto stalk development, plant type,

 pigmentation, leaf and stem

 pubescence.

Flowering : Rogue off-type plants, which differ inagronomic and morphological

characteristics, before pollen

shedding starts.

Post flowering:

Rouge off-type and diseased plants.

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� Pr ocedures for r oguing

� Select responsible people and pr ovidepr oper training on the identif ication and

removal of off types.

� Each member  of  the r  oguing team should

have a narr ow zone to observe. One member considers a maximum of 2 r ows.

� Short r oguing in a corner  of  the f ield and

wo

rk thr  o

ugh it slo

wly, walkingp

arallel andin the same direction down the r ows.

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� Detasseling� A detasseling team comprised of  sincere, eff icient workers

should be employed for this work.

� The detasseling team has to work in the f ield everyday, rain

or shine.

� Tassel should be pulled when they are well out of  the

³boot´. This of ten occurs 1-2 days af ter the tassels are f irst

visible.� If  the detasseling is done before optimum stage, 1 or  2

leaves may be removed with the tassel, or the tassel may

break off  and not completely removed. Removal of  tassel

along with leaves may reduce the seed yield.

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� Mechanical detasseling

� Pollination� It is estimated that an average tassel may produce as

many as 25 million grains to pollinate 300-600 kernels

in any given ear. Thus for every seed to be pollinated,

at least 25,000 pollen grains are available.

� Harvesting

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Operations/ Steps Followed in Harvesting

and Post-harvest pr ocessing of Maize

Time Of Harvesting

Husking, Sorting And Harvesting method

Drying

Shelling

Cleaning

SeedTreatment

GerminationTests Weighing, Bagging, Tagging And Sewing Seed

Storage

Carry-over Seed

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HarvestHarvest -- TimingTiming

� Seed should be harvested when

physiological or functionalmaturity is attained. This generally

coincides with the maximum

accumulation of dry matter and is

know as physiological maturity.

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Indications of seed reaching maturityIndications of seed reaching maturity

Milk layer Dry husks

Black layer 

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HarvestHarvest ± ± TimingTiming -- EarlyEarly

� At physiological maturity (30 ± 35%

moisture)

� Advantages

a) best seed quality

b) market seed earlier 

c) land availability for subsequent crop

� Disadvantages

a) Requires mechanical drying facilities

b) Cost

c) Risk of heat damage

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HarvestHarvest ± ± TimingTiming -- LateLate

� At 12 ± 16% moisture

� Advantage - lower cost

� Disadvantage ± exposure of seed toundesireable elements such astemperature and moisture extremes,diseases, insects, birds, theft, etc.

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Male line harvest before hybrid seed harvest

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Sorting/Selection

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Drying the Seed CropDrying the Seed CropDefined ± process through which moisture is

removed from the seed until the moisture

content is low enough to permit storage of 

the seed for relatively long periods of time

without deteriorationRecommended seed moisture

 ± Harvest = 30-35%

 ± Shelling = 14-16% ± Storage = 12%

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Drying the Seed CropDrying the Seed Crop

Sun drying

Usually done before shelling on a patio

with a concrete f loor  or  on black

plastic sheeting

Labor is required to spread and turn

cobs (or grain) to evenly expose

them to sun

Long drying time where seed may be

exposed to rain, insects, etc.

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