(Hybrid Seed Production in Maize, Types of hybrids, Single and double-cross hybrid, Isolation distance, Thinning, Detasseling, Stages of inspection, female and male ratio, harvesting)
Hybrid Seed Production in Maize ppt
In this article, we are going to explain the Hybrid Seed Production in Maize, how to make hybrid maize seeds. Maize is an important cross-pollinated crop that can be grown in all three seasons but is mainly grown in the Kharif season.
Hybrid maize seeds
Table of Contents
Types of hybrids in maize:
- Single cross hybrids
- Modified single cross hybrids
- Three-way cross hybrids
- Double cross hybrids
- Double top cross hybrids
- Top cross hybrids
Number of isolations and parents required for different types of hybrid seed production :-
| Hybrid | Combinations | Parents | Isolations |
| Single cross | Inbred x Inbred | 2 | 3 |
| Modified single cross | (IA x IAI) x IB | 3 | 5 |
| Three way cross
Double cross Top cross Double top cross |
F1 x Inbred
F1 x F1 Inbred x Var. F1 x Var. |
3
4 2 3 |
5
7 3 5 |
Why single cross hybrids:
Now the focus has been shifted to popularize single cross hybrid technology in this country to exploit maximum heterosis to enhance production and productivity levels of maize to meet envisaged demand.
- High productivity potential
- High acceptability among farmers because of high uniformity
- Involves only two parents in comparison to multiparent hybrids
- Require less land infrastructure –only three isolations in comparison to multi-parent hybrids. Two isolations for parental lines and one isolation for hybrid seed production.
- Low cost of hybrid seed production
- Tolerant to abiotic stresses
- Can generate employment opportunities for rural people particularly agriculture graduates
- High market acceptability
Pre Requisite of Quality seed yield
- Productive, uniform and genetically diverse inbred lines.
- Proper isolation distance ( Minimum 500 mts )
- Technology (Package practice).
- Technically experienced manpower.
- Stress-free season.
- Proper site selection.
- Fertile land and good quality of irrigation water
- Dry weather at maturity
- Moderate temperature
- Economics of hybrid seed production
Isolation distance of Hybrid seed production in maize
400-500 m is required between two maize genotypes.
Single cross hybrid seed production in Maize
- Well-drained, weed and disease-free soil and preferably the fields where the preceding crop was not maize to minimize rouging and maintain the genetic purity.
- Appropriate time of sowing for better crop establishment.
- Time of sowing to avoid flowering during heavy rains and low temperature
- Rains during flowering wash the pollen
- Low temperature causes mortality and killing of anthers.
Removal of off-type plants & Thinning For Hybrid seed production in maize
- Early Stage (12-15 DAS)
- off-type plants and thining
- Proper plant to plant distance 20-25 c.m.maintained to provide an equal opportunity to each plant to grow,
- At knee-high stage
- At flowering i.e. before anthesis.
- Dissimilar plants should be removed from the male and female lines to maintain the genetic purity of the seed.
- tassel shape, size, glumes, anther and silk colour should not vary in both the parents
DETASSELING IN HYBRID SEED PRODUCTION IN MAIZE
- Detasseling in females before anthesis
- It should be practised row-wise
- A person should follow to monitor each row to check no part of the tassel is left inside
- Detasseling continues for 8-10 days.
Precautions in Detasseling
- While detasseling, the leaf should not be removed.
- Removal of 1 to 3 leaves along with tassel reduces 5-15 % yield.
- The removed tassel should not be thrown in the field but fed to the cattle as it is nutritive fodder.
FEMALE AND MALE RATIO OF HYBRID SEED PRODUCTION IN MAIZE
- Pollen shedding potential of the male parent
- M: F synchrony: Female should be early
- M pollen dehiscence should coincide with F silking.
- In general M: F ratio should be 1:2 or 1:3 or 1:4
SEED PARENT CHARACTERISTICS HYBRID SEED PRODUCTION IN MAIZE :-
- Productive
- Strong
- Long cobs with complete exertion
- Low cob placement
- Lax tassel
- Shorter Anthesis Silking Interval (ASI)
- Nutrient responsive
- Stay green trait
- Erect leaves
- Resistant/tolerant to biotic and abiotic stresses
- Strong root system
POLLEN PARENT CHARACTERISTICS HYBRID SEED PRODUCTION IN MAIZE
- long main branch with few secondary branches
- Long duration of pollen shedding
- Taller than the seed parent
- Attractive grain colour
- Strong plant resistance to lodging with the better root system
- High yield potential
- Resistance/tolerant to biotic and abiotic stresses
HARVESTING OF HYBRID SEED IN MAIZE
- First, harvest male parents. Keep separately.
- Moisture in grain at harvesting should be around 20% in the female seed.
- The harvested cobs should be spread evenly instead of making heap.
- Harvested cob should be kept on Tarpauline to avoid infestation from pests and diseases
DRYING AND SORTING OF SEED COBS:
- The drying of the cobs should not be done either on the cemented or on the ground,
- Rather it should be dried on tarpaulin sheets to avoid seed injury
- During the night the cobs should be kept covered.
- To maintain the purity, dissimilar, diseased and pest-infested cobs should be removed before shelling.
- Cobs should be dried up to 13-14% moisture content before shelling.
STAGES OF CROP INSPECTION IN MAIZE
At the time of sowing:
- Monitor the land,
- Isolation distance,
- Planting ratio of male: female,
- Proper sowing time,
- Seed treatment
During pre-flowering/vegetative stage:
- To verify the rouging and removal of off-type plants
During flowering stage:
- To check disease and pest infestation
During post-flowering and pre-harvest stage:
- To remove the late and diseased plants
The harvesting time of Hybrid Maize seed
- To see the proper time of harvesting & sorting of cobs
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