Maize Varieties and Quality SeedsDr. Bhagya Rani Banik

Importance of maize1. 2. 3. 4. 5. HIGH YIELD Year round production C4 crop, the crop of global warming Less disease and pests Versatile use; 1. Food (flour, flakes, soup) 2. Feed (poultry, dairy, fish) 3. Baby corn, green corn, pop corn 4. Starch, oil 5. Fodder, fuel 6. Green manure

2500.00

8.00

Maize Area, Production and Yield in BangladeshArea (000ha) and Production (000 ton)7.00

2000.00

1500.00

4.00

1000.00

3.00

2.00

500.001.00

0.00

0.00

Year

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

-1

5.00

Yield (tonha )

Area (000 ha) Production (000) ton Yield (t/ha)

6.00

0 -1 09 20 9 -0 08 20 8 -0 07 20 7 -0 06 20 6 -0 05 20 5 -0 04 20 4 -0 03 20 3 -0 01 20 2 -0 01 20 1 -0 99 19 0 -0 99 19 9 -9 97 19 8 -9 97 19

7 -9 95 19 6 -9 95 19 5 -9 93 19 4 -9 93 19 3 -9 91 19 2 -9 91 19 1 -9 89 19 0 -9 89 19

Maize growing seasons in BangladeshSeasons

Growing Months

Climate Temp. Av. Max.28.80 C 30.80 C

Temp. Av. Min.17.50 C 21.90 C

% RH75 74

Maize Ecosystems

% Maize area85 15

Winter Summer

Nov-Dec. to Apr-May Feb-Mar to May-Jun

Sub-tropical Tropical

Table 3. Production target in 2010, 2015, 2020, 2030 and 2050 (as far as available)

Projected population/ Demand/ Production target of maize Projected pop. (mil.) Demand (mil. ton) Target area (m ha) Target avg. yield (t/ha) Prodn, target (mil. ton)Source: BBS and MoA

2010

Projected Year 2015 2020

2030

148.0 1.88 0.20 6.5 1.30

156.7 2.25 0.30 7.5 2.25

166.9 3.00 0.35 8.0 2.80

190.6 3.50 0.40 8.5 2.97

Farmers field, Comilla (22 May 2009)

Reasons for popularity:1. High grain yield 2. Two cropping seasons per year 3. Flexibility in planting time 4. Fits well in cropping pattern 5. Low risk of complete crop damage 6. Can be used as fresh, boiled, dried & fried

Problems1. Pollination control 2. Inbreeding depression 3. Maintenance of inbred lines 4. Maintenance of hybrid variety ? 5. Short viability of seed 6. Shelling 7. Drying 8. Milling 9. Eating 10. Selling

Problems1. Pollination control 2. Inbreeding depression 3. Maintenance of inbred lines 4. Maintenance of hybrid variety ? 5. Short viability of seed 6. Shelling 7. Drying 8. Milling 9. Eating 10. Selling

Variety development1. 2. 3. Composite/Synthetic/OP Hybrid: Single, 3-way, double cross Top cross/Double top cross hybrid

4. 5. 6.

Sweet corn Pop corn Baby corn (vegetable)

ClassificationDent maize Flint maize Sweet corn Flour corn Pop corn Pod maize Waxy maize Baby corn

Achievement of maize improvement at BARIList of composite maize varieties developed by BARIVariety 1. Barnali 2. Shuvra 3. Mohar 4. BARI Maize 5 5. BARI Maize 6 6. BARI Maize 7 7. Khoibhutta 8. BARI Sweet corn 1 Yield (t/ha) 4.0-5.0 t/ha 4.5-5.5 t/ha 4.5-5.6 t/ha 5.5-6.0 t/ha 5.7-6.2 t/ha 5.5-6.5 t/ha 4.5-5.0 t/ha 10-10.5 t/ha Year of release 1986 1986 1986 1997 1998 1998 1986 2002 Suitable areaThe crop can be cultivated all over Bangladesh The crop can be cultivated all over Bangladesh The crop can be cultivated all over Bangladesh The crop can be cultivated all over Bangladesh The crop can be cultivated all over Bangladesh The crop can be cultivated all over Bangladesh The crop can be cultivated all over Bangladesh

Homestead areas

Achievement of BARIList of hybrid maize varieties developed during 2000-2010Hybrid Variety BARI hybrid maize 1 BARI hybrid maize 2 BARI hybrid maize 3 BARI hybrid maize 4 BARI hybrid maize 5 BARI hybrid maize 6 BARI hybrid maize 7 BARI hybrid maize 8 BARI hybrid maize 9 BARI hybrid maize 10 BARI hybrid maize 11 Yield (t/ha) 7.5 - 8.5 8.0 -9.0 9.0 -9.5 7.5 - 8.5 9.0 - 10.0 9.8 - 10.0 10.5-11.2 9.7 -11.5 10.2 -12.0 9.0 -11.5 9.5 -11.5 Maturity 140-145 138-142 144-150 142-146 140-145 141-145 141-145 142-146 145-150 145-150 147-153 Year of release 2000 2002 2002 2002 2004 2006 2006 2007 2007 2008 2008 Grain colour and texture Orange-yellow, flint Orange-yellow, semi-flint Yellow, dent Orange-yellow, flint Orange-yellow, flint Yellow, flint Yellow, flint Yellow, dent Orange-yellow, dent Yellow, flint Yellow, flint

Flint maize

Flint and Dent Maize

Dent maize

Sweet cob corn with husk

Dehusked Sweet Corn

Sweet corn

Mature pop corn

Popped corn

Pop corn

Baby corn with husk

Baby corn to harvest

Baby CornBaby corn without husk

Estimation of heterosis Mid parent heterosis % = F1-Mean of parents (MP) --------------------------------------X 100 Mean 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

Concept of hybrid maize development Source materials Development and evaluation of parent materials Development of hybrids

Source/base materials Heterozygous and heterogenous/homogenous Broad based Achievement -Will be more with moregenetic distances/ diversed alleles

Development and evaluation of parent materials By enforced selfing followed by selection Sibbing whenever necessity will arise Evaluation by combining ability test

Terminology related to hybrid technology Inbred line : A nearly homozygous line developed bycontinued inbreeding, usually selfing, accompanied by selection.

Inbreeding :

Mating between individuals related by descent or ancestry.

Inbreeding Depression : Loss in vigour due to inbreeding. Heterosis : Superiority of F1 over the parents (or eveninferiority to both the parents).

Hybrid Vigour : Synonymous to Heterosis. Hybrid : Progeny from hybridization between two or more strains. Hybrid variety : A hybrid variety is the F1 generation from across between two different strains.

Types of hybrids a) Single cross: 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) Modified single cross : A modified single cross is across of the type (A x A1) X C where A and A1 are sister lines.

c) Three way cross : 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 cross : 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)

Sequential steps in hybrid seed production Commercial hybrid maize seed production broadly involve the following steps : 1. Maintenance and breeders seed production of the parental lines 2. Multiplication/production of breeders seed, certified seed foundation seed

3. Production of hybrid seed i.e. single cross, threeway cross and double cross 4.Processing of the hybrid seed

Breeder seed The breeders seed refers to the seed stock of a parental line developed by plant breeder. It is the type of seed with highest level of purity. The plant breeders responsibility is to maintain and increase the breeders seed.

Foundation seed The breeder seed is multiplied to produce foundation seed. Responsibility for production of foundation seed is often assigned to specialized agencies.

Certified seed The foundation seed is multiplied to produce certified seed. The seed growers under inspection provided by the certifying agencies produce certified seed.

Different techniques in hybrid seed production of maize Site selectionLand type Isolated field requirementTable 1. Showing number of isolated plots/fields necessary for different types of conventional hybrids

Types of hybrid

Inbred parents 2 3 4

SC Hybrid parent 1 2 1 1 1

Total

Single cross Three-way cross Double cross

3 5 7

Time of sowing Plant population densities Avoiding mixtures of males and females Female : Male ratios

Isolation1.

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 contaminate sources. This time may slightly vary with different varieties.

Techniques applied for synchronization of flowering*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 to 30cm tall, cutting away half of the plant material.

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

Treatment 20 cm cutback to 10 cm 60 cm cutback to 30 cm 90 cm cutback to 45 cm

Delay in flowering* 4 days 7 days 7 days

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

Improving pollen distribution and seed set Collect pollen from male rows and hand pollinate Physically shake male lines.

Roguing There are three basic types of rogues Volunteer corn : These are corn plants grown in thefield from previous year outside the production field but within the isolation limit.

Off types: Any corn plants in the seed production fieldother 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.

Two types of contamination can occur in the fieldCaused by crosspollination with other maize plants growing in the field or in the isolation area. It can also be caused by accidental self-pollination of female parents of hybrids due to improper detasseling.

Genetic contamination -

Mechanical contamination - Caused by mixingseed or transplanting of undesirable plants

When to rogueRoguing should be done during the following stages of plant growth :

Post emergence

Vegetative development

: Rogue off-type plants that are often easily identified due to their difference in size and their position out of the rows. : Rogue off-type plants, which differ from the given genotypes in respect to stalk development, plant type, pigmentation, leaf and stem pubescence. : Rogue off-type plants, which differ in agronomic and morphological characteristics, before pollen shedding starts. : Rouge off-type and diseased plants.

Flowering

Post flowering

Procedures for roguing Select responsible people and provide proper training on the identification and removal of off types. Each member of the roguing team should have a narrow zone to observe. One member considers a maximum of 2 rows. Short roguing in a corner of the field and work through it slowly, walking parallel and in the same direction down the rows.

Detasseling A detasseling team comprised of sincere, efficient workers should be employed for this work. The detasseling team has to work in the field everyday, rain or shine. Tassel should be pulled when they are well out of the boot. This often occurs 1-2 days after the tassels are first 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.

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

Operations/ Steps Followed in Harvesting and Post-harvest processing of Maize Time Of Harvesting Husking, Sorting And Harvesting method Drying Shelling Cleaning Seed Treatment Germination Tests Weighing, Bagging, Tagging And Sewing Seed Storage Carry-over Seed

Harvest - Timing Seed should be harvested when physiological or functional maturity is attained. This generally coincides with the maximum accumulation of dry matter and is know as physiological maturity.

Indications of seed reaching maturity

Dry husks

Milk layer

Black layer

Harvest Timing - Early

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

Harvest Timing - Late At 12 16% moisture Advantage - lower cost Disadvantage exposure of seed to undesireable elements such as temperature and moisture extremes, diseases, insects, birds, theft, etc.

Male line harvest before hybrid seed harvest

Sorting/Selection

Drying 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 deterioration Recommended seed moisture Harvest = 30-35% Shelling = 14-16% Storage = 12%

Drying the Seed Crop

Sun dryingUsually done before shelling on a patio with a concrete floor 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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