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Hybrid Rice Seed Production Techniques (HRSPT)

3
Jul

Production of nucleus and breeder seed of three line hybrid system

1. Breeder seed production involves the further multiplication of A, B and R lines using nucleus seed.

2. The seed material obtained from systematic paired crossing can be used to produce the breeder seed. Breeder seed production has to be taken up in a field where no rice crop is grown during previous crop season. Recommended isolation distance is 300-500 meters.

3. A row ratio of 2: 4 and 2: 6 can be adopted for nucleus and breeder seed production respectively. Utmost care is needed for meticulous rouging as the seed has to be very pure.

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

Steps involved in three 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/hybridriceseed
3
Jul

Lines used in three line System of Hybrid Seed Production

The CGMS system basically consists of three lines viz.,

1. CMS line (A line).

2. Maintainer line (B line).

3. A restorer (R) line.

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

Three line system of Hybrid Seed Production

1. The cytoplasmic-genetic male sterility (Genic-cytoplasmic male sterility) system is the result of interaction between specific sterility inducing cytoplasm and the nuclear genes.

2. To get male sterility expression both sterile cytoplasm (s) and recessive (rf) nuclear genes are required.

3. A combination of sterile (S) cytoplasm and dominant (Rf) nuclear genes or normal (N) or fertile cytoplasm and recessive (rf) nuclear genes result in fertile plants.

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

Seed Production of Hybrid Rice by three different methods.

Seed production of hybrid rice can be done by three different methods. Those are

1. Three line system of hybrid seed production.

2. Two line system of hybrid seed production.

3. One line system of hybrid seed production.

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

Genotypic Classification of Male Sterility

Classification of male sterility and its exploitation in crop plants is on genotypic basis which includes

1. Cytoplasmic male sterility (CMS).

2. Cytoplasmic genetic male sterility (CGMS).

3. Genetic male sterility (GMS).

4. Genetically engineered male sterility.

5. Chemically induced male sterility.

6. Environmental sensitive genetic male sterility (EGMS).

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

Phenotypic Classification of Male Sterility

Phenotypic Classification of Male Sterility include Structural male sterility, Sporogenous male sterility, Functional male sterility

1. Structural male sterility: Anomalies in malformation of male sex organs / missing altogether.

2. Sporogenous male sterility: stamens develop, but pollen grains do not develop or rare due to microsporogenous cell abortion before / during /after meiosis.

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

How Male Sterility will occur in Plants

It is essential to look at how male sterility manifests in plants before classifying them into various categories. One of the higher level of manifestations is

1. The absence of normal formation of male organs (stamens) in bisexual plants or no male flowers in dioecious plants.

2. Failure to develop normal microsporogenous tissue – anther.

3. Abnormal microsporogenesis leading to deformed or unviable pollen.

4. Abnormal pollen maturation : inability to germinate on compatible stigma.

5. No dehiscent anthers but viable pollen – sporophytic control.

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

Classification of Male Sterility

There are basically, two types of classification of male sterility

1. The phenotypic classification which includes structural, sporogenous and functional male sterility.

2. The genotypic classification includes genetic male sterility, cytoplasmic male sterility and genetic- cytoplasmic male sterility

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

Desirable Characteristics of Maintainer and Restorer lines

Characteristics of Maintainer and Restorer lines should be:

1. Long and contain 125 or more spikelets.

2. Completely exserted from the flag leaf.

3. Filaments should be long facilitating complete anther exertion from the floret.

4. Anthers should be large and plumpy with more nuclear of pollen grains.

5. The anther should dehisce and shed most of its pollen only after it has exserted from the floret

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

Desirable Characteristics of the CMS line

 

Desirable characteristics of CMS line are

1. High seed yields depend on desirable panicle, floret, and stigma characteristics of the CMS line.

2. The panicle should be exserted fully from the flag leaf as far as possible.

3. There should be at least 100 spikelets per panicle.

4. The floret should open wide and remain open for at least 45 minutes or longer.

5. Blooming florets should have well exserted stigmas.

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

Restorer Line (R Line)

1. Any rice cultivar that restores fertility in the F1 when it is crossed to a CMS line is called a restorer.

2. The restorer is also called the pollen parent, the male parent, or the R line.

3. The R line is used as the pollinator for the CMS parent for hybrid seed production.

4. Growth duration may or may not be similar to that of CMS lines.

5. Panicles exsert fully out of the flag leaves.

6. Anthers are yellow, plumps, and shed pollen. Flowering lasts for about 5 days.

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

Maintainer Line (B Line)

 

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

Male Sterile Line

 

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

Hybrid Rice Parental Lines

Hybrid Rice Parental Lines includes

1. Male sterile line or A line

2. Restoral line or R line

3. Maintainer line or B line

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

Hybrid Rice Seed

 

1. Hybrid rice seed is produced when the egg is fertilized by pollen from the anthers of a rice plant from a different variety or line.

2. Hybrid rice seed is the first filial (F1) generation obtained by crossing two rice varieties that are genetically different or offspring of a cross between two genetically diverse parents.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
Photo Courtesy: 
http://www.knowledgebank.irri.org/hybridriceseed
2
Jul

Inbred Rice Seed

 Inbred rice seed is produced when the egg inside the ovary is fertilized by pollen grains shed from

             1. Anthers borne in the same spikelet.

              2. Anthers from other spikelets of the same plant.

File Courtesy: 
Agro Techniques for Hybrid Rice Cultivation and Seed Production - 2005, DRR Training Manual
Photo Courtesy: 
http://www.knowledgebank.irri.org/hybridriceseed/Inbred_rice_seed.htm
2
Jul

Stages of Seed Formation

 

File Courtesy: 
Morphological and Floral Characteristics of Rice( Dr. A. S. Hari Prasad DRR)
Photo Courtesy: 
Dr. A.S. Hari Prasad ( DRR)
2
Jul

Process of Seed Formation

The steps involved in seed formation are

a. Pollination is the first step in reproduction.

b. Pollen grains are shed from the anthers and fall onto the feathery stigmas.

c. Fertilization is the second step in seed formation.

d. The pollen that reaches the stigma germinates and forms a pollen tube that carries the male nuclei inside the ovary for fusion with the egg nuclei.

File Courtesy: 
Morphological and Floral Characteristics of Rice ( Dr. A. S. Hari Prasad DRR)
Photo Courtesy: 
Dr. A.S.Hari Prasad ( DRR)
2
Jul

Stigma Characteristics

1. It is desirable to possess longer and exserted stigma, longer stigma receptivity and wider angle of floret opening is essential for better outcrossing.

2. Floret opening angle varies among cultivars from 25 degrees in long slender spikelets to 35 degrees in short, coarse spikelets.

3. Rice Stigma remains receptive for 2-3 days from the day of opening.

File Courtesy: 
Morphological and Floral Characteristics of Rice( Dr. A. S. Hari Prasad DRR)
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