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Hybrid Rice Seed Production Techniques (HRSPT)

9
Jul

Nursery management

 

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
Photo Courtesy: 
Dr. Hari Prasad ( DRR)
9
Jul

Favourable climatic conditions for hybrid rice seed production

Climatic conditions have profound influence on the seed yields. Sowing of the parental lines should be planned in such a way that the flowering coincides with the most favourable climatic conditions, which are as follows:

1. Daily mean temperature of 24 – 300 c
2. Relative humidity ranging from 70 – 80 %
3. The differences between day and night temperatures should not be more than 8–100c, preferably 5 – 70c
4. Sufficient sun shines with moderate wind velocity.
5. There should not be rains continuously for three days during the flowering period.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
9
Jul

Barrier isolation

 

1. In some places, the natural topographic features such as mountains, rivers, forests can serve as the most effective barrier.

2. A crop barrier with Maize, Sugarcane, Sesbania covering a distance of 30 m would also serve isolation.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
Photo Courtesy: 
Dr. Hari Prasad ( DRR)
9
Jul

Time isolation

 

1. Wherever, it is difficult to have space isolation, a time isolation of over 21 days would also be effective.

2. It means that the heading stage of the parental lines in hybrid seed production plot should be 21 days earlier or later than that of other varieties grown within the vicinity.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
Photo Courtesy: 
Dr. Hari Prasad ( DRR)
9
Jul

Space isolation

 

1.
A space isolation of 50 – 100 m is sufficient for hybrid seed production, which implies that within this range no other rice varieties should be grown except the pollen parent.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
Photo Courtesy: 
Dr. Hari Prasad ( DRR)
9
Jul

Isolation

 

1. Rice pollen grains are very small and light, and can be carried very far with the wind.

2. In order to ensure the purity of hybrid seed and avoid pollination by unwanted rice varieties, the hybrid seed production plots should be strictly isolated by different methods.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
9
Jul

Choice of location

1. Choosing a desirable location for hybrid seed production is very important.

2. In the well isolated area, fertile paddy field with needed irrigation and drainage system, sufficient sunshine, and no serious disease and insect problems are essentially needed.

9
Jul

Production of hybrid seed

The success of hybrid seed production depends on various factors such as
1. choice of field
2. Isolation
3. Sowing time
3. Planting pattern
4. Weather conditions during the period of flowering
5. roguing synchronization in flowering of parental lines, supplementary pollination techniques, proper harvesting, processing, packing and effective seed distribution etc.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
7
Jul

Maintaining the purity of TGMS lines

• Selecting about 100 plants with the typical characteristics of the original EGMS lines and planting them separately in pots.

• Transferring the pots at the sensitive stage into a glasshouse with a controlled temperature or phytotron where appropriate temperature and photoperiod are set.

• Monitoring pollen sterility critically at the time of heading and selecting plants with 100 per cent sterility.

• Ratooning selected plants in suitable short-photoperiod/low temperature conditions and collecting their selfed seed (nucleus seed).

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
3
Jul

Maintaining the purity of TGMS lines

1. Selecting about 100 plants with the typical characteristics of the original EGMS lines and planting them separately in pots.

2. Transferring the pots at the sensitive stage into a glasshouse with a controlled temperature or phytotron where appropriate temperature and photoperiod are set.

3. Monitoring pollen sterility critically at the time of heading and selecting plants with 100 per cent sterility.

4. Ratooning selected plants in suitable short-photoperiod/low temperature conditions and collecting their selfed seed (nucleus seed).

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
3
Jul

Multiplication of EGMS lines

1. EGMS lines are multiplied at appropriate locations and seasons where stable fertility inducing environmental (photoperiod /temperature) conditions prevail for a continuous period of 30 days.

2. Let us take the example of TGMS lines which turn to fertility at lower temperature and the most ideal temperature regime to induce higher fertility is 27/210C.

3 In this case, the TGMS line has to be planted in such a way that the sensitive stage (5-20 days after planting) occurs in the middle of the fertility inducing phase.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
3
Jul

Seed production of two line hybrids

1. Seed production of two-line rice hybrids is not much different from that of three line hybrids.

2. Most important consideration is to precisely determine the location or season which is ideal for inducing complete male sterility.

3. Currently the seed yields obtained in two-line hybrid seed production in China range from 2.3 to 3.0 t/ha which is comparable with seed yields obtained with three line hybrids

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
3
Jul

The major constraints to develop and using TGMS lines

The major constraints to develop and using TGMS lines in the tropics are

1. Limited availability of stable TGMS germplasm.

2. Lack of training and experience of researchers in breeding and using TGMS lines and knowledge.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
3
Jul

Advantages of Two-line Vs Three-line System of Heterosis Breeding

1. Wide choice of parental lines hence increased chances of identifying heterotic hybrids.

2. Seed Production system is simpler and more efficient.

3. Risk of outbreak of epidemics associated with large scale use of unitary source of cytoplasm as well as the negative effects of sterility inducing cytoplasm are avoided altogether.

4. In Rice, two-line system is specifically useful for developing hybrids in Basmati and Japonica type.

5. Magnitude of heterosis in two-line hybrids is 5 to 10% higher than in three line hybrids.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
3
Jul

Photo-Thermo Sensitive Genetic Male Sterility (PTGMS)

1. Photo-Thermo Sensitive Genetic Male Sterility line is controlled by the interaction of photoperiod and temperature. Most of the PGMS lines earlier identified such as the classical Nongken 58S were later reported to fall under this category.

2. PTGMS is just similar to the TGMS system in all respects except for the temperature regime in between the CSP and CFP, where the photoperiod sensitivity is observed.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
3
Jul

Temperature Sensitive Genetic Male Sterility (TGMS)

1. Plants are sterile when temperature exceeds 32°C/24°C (day/night) and becomes fertile when the temperature is below 24°C/18°C (day/night).

2. However, in few cases, sterility is observed at lower temperatures and fertility is observed at higher temperatures.

3. Such type of male sterility is referred to as ‘Reverse TGMS type’.

4. TGMS system can be utilized in tropical and sub-tropical countries, where there are large temperature differences across locations, regions, and seasons and at different attitudes.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
3
Jul

Photoperiod Sensitive Genetic Male Sterility (PGMS)

 

1. The line is sterile when the photoperiod (day light) exceeds 14 hrs and the same line becomes fertile when subjected to photoperiod of < 13 hrs.

2. PGMS system is useful and can be deployed in temperate countries where the day length differs considerably during different seasons.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
Photo Courtesy: 
http://www.knowledgebank.irri.org/ricebreedingcourse/Hybrid_Rice_Breeding_&_Seed_Production.htm
3
Jul

Environment-Sensitive Genetic Male Sterility (EGMS) system

The EGMS comprises of the following three types:

1. Photoperiod sensitive genetic male sterility (PGMS)

2. Temperature sensitive genetic male sterility (TGMS)

3. Photo-thermo sensitive genetic male sterility (PTGMS)

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
3
Jul

Two-line System of Hybrid Seed Production

 

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
Photo Courtesy: 
http://www.knowledgebank.irri.org/ricebreedingcourse/Hybrid_Rice_Breeding_&_Seed_Production.htm
3
Jul

Purification of parental lines

Parental lines have to be purified under the direct supervision of the rice breeder. Purification process essentially involves four steps :

I. Growing the source material (Source Nursery).

II. Test crossing (Test Cross Nursery).

III. Evaluating the test crosses (Identification Nursery).

IV. Multiplication of the lines (Multiplication Nursery).

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
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