Rice in India : A Status Paper
|HISTORY AND CONCEPT OF HYBRID RICE|
The first artificial hybrid was produced by Thomas Fairchild during 1717 by crossing between sweet william (Dianthus barbatus and carnation (Dianthus caryophyllus). Thereafter, several scientists used hybridization for scientific studies as well as for crop improvement in the breeding programme. Joseph Koelreuter, one of the famous scientist who made several crosses in Tobacco during 1760-1766 and reported hybrid vigour in F1. At the end of nineteenth century, hybridization was widely used for different crop improvement programme. In the modern era hybridization is the most common method is applied in crop improvement and large number of varieties have been developed in various crops by hybridization.
For development of hybrid, intensive research was started in India during 1952 in the Maize Coordinated Project and first hybrid was released during 1960. Subsequently three more maize hybrids were also released during 1960. Later on, research work was initiated on Bajra and Pearl millet and Sorghum (Jowar) crops during 1961 and first hybrid in sorghum and in Pearl millet was released during 1964.
Success in hybrids of maize, pearl millet, sorghum, cotton, sunflower and pigeonpea breeding programme encouraged researchers to explore commercial exploitation of heterosis in rice. In mid seventies, rice hybrids were also developed and cultivated in China.
Efforts to develop and use of hybrid rice technology in India was initiated during 1970. But the research works were systematized and intensified since 1989 with a mission mode project. With the concerted research work, the country developed half a dozen rice hybrids each from public and private sectors within a short span of five years. The first four rice hybrids were released in the country viz. APHR-1, APHR-2, MGR-1 and KRH-1 during 1994. Subsequently, two more hybrids viz. CNRH-3 and DRRH-1 were also released. The total number of 18 rice hybrids have been released till December 2001. The details of salient features of these hybrids are given in Table-8.
In the mid seventies rice hybrids were also developed and cultivated in China. The China cultivated rice hybrids in an area of about 55% of its total area under rice during 1991. The result indicated that the hybrid rice have greater potential to increase productivity by 15-20% than the high yielding varieties.
The breeding method in which mating or crosses are made between two plants or lines of different genotype is known as hybridization. The seeds as well as the progeny obtained from hybridization is known as hybrid or F1.
There are two breeding approaches in hybrid rice technology :
Three-line breeding or Cytoplasm Genetic Male Sterility (CGMS).
In this system, three lines are used that’s why this system is called three line breeding. These line are:-
Cytoplasmic Genetic Male Sterile line (CGMS Line) or A-Line
Maintainer Line or B-Line, and
Restorer line or R-Line.
In this system of breeding, sterility/fertility is due to interaction of nuclear gene with the cytoplasm. In A-line, sterile cytoplasm has been derived from wild or weedy species and the nucleus has recessive fertility restorer genes. Therefore, the A line is sterile. However, maintainer line or B-line has normal cytoplasm and fertile pollen contains recessive fertility restorer genes.
A–Line and B–Line are exactly same genetically but they differ only in respect of cytoplasm content. A–Line has sterility inducing enzyme whereas, B–Line has normal cytoplasm. The R-Line possesses fertility restorer genes in dominant condition. The R-Line will be always fertile with respect to the cytoplasm either it is sterile or fertile. As regards multiplication of A-Line, it is crossed with B-Line. Since two lines have fertility genes in recessive condition and cytoplasm is controlled by sterility inducing gene in A–Line, therefore as a result of crossing F1 is sterile i.e., A–Line.
In hybrid seed production A–Line is crossed with R–Line. As R–Line possesses fertility restorer gene in dominant condition, though the cytoplasm contributed by A-Line is sterility inducing one. As a resultant, F1 which is used as commercial hybrid is fertile one. The three line breeding methodology is shown in the diagrammatic form below :
This approach is a potential alternative tool to overcome some of the limitations. They are :-
Use of environment sensitive genic male sterility (EGMS)
Use of chemically induced male sterility
In EGMS System, genotype that exhibit sterility/fertility with respect to temperature are called Thermo-Sensitive Genic Male Sterility (TGMS) line and the lines showing sterility/fertility with respect to photoperiod are named Photoperiod Sensitive Genic Male Sterlity (PGMS) lines. These only two lines viz. female and male lines are required for developing hybrids and therefore this approach is called Two Line Breeding. The two line breeding methodology is shown in the diagrammatic form below -
Chemically Induced Male Sterility
Male sterility is artificially induced by spraying Gametocides to cause stamen sterility without harming the pistil. The chemical which makes sterile the stamen, plant can be used as female parent for producing hybrid seed. Two selected lines are planted in alternate strips and one is utilized as female (chemically sterilized) and is pollinated by the other line, for production of hybrid seed.
Hybrid rice cultivation is a new technology and it has to be popularized among the farmers in the rice growing areas. The increase in yield in the case of hybrid rice is about 15-20% than the existing high yielding varieties of rice. Economics of hybrid rice cultivation as well as the cultivation of high yielding varieties of rice, if both are cultivated in similar conditions with good management package of practices, on an average an additional net profit of Rs. 3,500/- per hectare can be obtained from hybrid rice cultivation. The additional cost in cultivation of hybrid rice is only the cost of seed as the cost of hybrid seed is higher than high yielding varieties. However, other cultivation practices remain the same as those of high yielding varieties of rice.
|SL||Name of Hybrid|
|Year of |
for the State
|Andhra Pradesh||130-135||7.14||Suitable for uplands of coastal Andhra Pradesh.|
|Andhra Pradesh||120-125||7.52||Grains are long and slender.|
|Tamil Nadu||110-115||6.08||Grains are medium slender, resistant to the pest, WB and Gall Midge.|
|Karnataka||120-125||6.02||Suitable for irrigated areas.|
|West Bengal||125-130||7.49||Grains are LB, suitable for Boro season.|
|Andhra Pradesh||125-130||7.30||Grains are LS, mild aroma, resistant to blast disease.|
|Karnataka||130-135||7.40||Grains are LB, resistant to the pest, BPH and blast disease, suitable for irrigated areas.|
|Tamil Nadu||120-125||6.25||Grains are MB.|
|Tamil Nadu||115-120||7.10||Grains are LS.|
|Maharashtra||125-130||6.15||Grains are LS.|
|12.||Narendra Shankar Dhan-2||1998||IR-8025A/|
|130-135||7.86||Grains are LS, resistant to the pest, BPH.|
|Plains of Uttar|
|15.||PA-6201*||2000||--||Eastern and some|
parts of Southern
|125-130||6.18||Grains are LS, resistant to the pest, BPH and blast disease.|
|16.||Pusa RH-10||2001||Pusa- 6A/|
|125||-||Aromatic Basmati Hybrid.|
|135-140||6 - 8||Plant height : 100-120 cms, Leaf : 24x1.5 cms,|
1000 grain weight-22g
Kernel : 6.21x2.06 mm,
L/B ratio : 3.01,
Non-Lodging, N responsive,
Grains : MS, suitable for well drained, irrigated condition, resistant to neck and rice tungro virus.
* - Private bred hybrid released by C.V.R.C.