Practical Achievements in Ideotype Breeding

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Practical Achievements in Ideotype Breeding

Ideotype breeding has significantly contributed to enhanced yields in cereals (Wheat and rice) and millets. (Sorghum and pearl millet) through the use of dwarfing genes, resulting in green revolution. Semidwarf varieties of wheat and rice are highly responsive to water use and nitrogen application and have wide adaptation. These qualities have made them popular throught the world. Spontaneous mutations have played significant role in designing new plant types in wheat and rice. The Norin 10 in wheat and Dee-geo-Woo-gene in rice are the source of dwarfing genes. These sources of dwarfing genes were obtained as a result of spontaneous mutations. Several high yielding Semidwarf varieties have been evolved in wheat and rice through the use of respective dwarf mutant. The Norin-10, dwarfing gene in wheat, the Dee-geo-woogen dwarfing gene in rice and the genic cytoplasmic male sterile system in sorghum and pearl millet laid the foundation of green revolution in Asia (Swaminathan, 1972). Thus, Ideotype breeding has been more successful for yield improvement in cereals and millets than in other crops.

In rice, the improved plant type includes,
1) Erect, short and thick leaves.
2) Dwarf stature,
3) Light leaf sheath,
4) High tillering capacity,
5) Responsiveness to high levels of nitrogen, and
6) High harvest index,

Examples of Semidwarf varieties of rice are IR-8, IR-20, TN1 etc. The Chinese variety Dee-geo-woogen is the source of dwarfing gene in all these varieties.

In wheat, the improved plant type included,
1) Short and still straw,
2) Insensitivity to photoperiods,
3) High response to nitrogen application,
4) High harvest index,
5) Resistance to different rusts.

The Chinese variety Dee-geo-Woogen is the source of dwarfing gene in all these varieties.

In sorghum and pearl millet, short statured hybrids have been developed through the use of dwarfing gene. The dwarf hybrids have made machine harvesting possible in these crops. In sorghum, combine harvesting has reduced the labour requirement by 1/8.

In cotton, as a result of high selection pressure for earliness, short stature and compactness in the past, there has been a gradual reduction in the overall plant size. The earlier varieties were later maturing, tall growing and spreading types leading to bushy appearance. The target shifted to development of varies with medium height, medium maturity and semi spreading habit. Now major emphasis is to evolve varies with sort duration, short stature and compact plant type.

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