Question

The majority of high yielding varieties of Indian rice have been developed by a cross between
(a) Oryza sativa japonica and Oryza sativa Indica
(b) Oryza sativa indica and Oryza nivara
(c) Oryza nivara and Oriza sataiva japonica
(d) Oryza nivara and Oryza rufipogon

Answer 1

By using plant breeding techniques the majority of high-yielding varieties of rice plants are produced by crossing between rice plants of Japanese species and Indian species.

Complete answer:
To create desired plant types that are suited for cultivation, they are purposely manipulated. This technique is called plant breeding. Plants that are created by various gene transfer methods are called transgenic plants. Producing transgenic plants is one of the techniques of plant breeding. This technique is employed to produce plants of desired characters. It is employed mainly in agricultural crops to increase the annual yield of a crop. Different species of plants are crossed resulting in new hybrid plants. Since 1960 species of japonicus and indicus have crossed and this results in high yielding varieties of crops for example Oryza sativa japonica and Oryza sativa Indica .

Additional Information: - Disease-resistant plants and the plants that give better yields are produced by using plant breeding techniques.
- During the period of 1960 to 2000, the production of rice increased from 35 million tons to 889.5 million tons obtained from hybrid rice plants developed by applying plant breeding techniques.
- Semi-dwarf varieties of rice which are high yielding varieties and are resistant to diseases are produced from IR-8 and Taiwan native-1 later in 1966, India developed semi-dwarf varieties of rice called Jaya and Ratna.
- Transgenic plants also showed better results in developing plants of desired varieties.
- To produce transgenic plants, the most commonly used vector nowadays is the Ti plasmid of Agrobacterium tumefaciens.
- The majority of high yielding varieties of Indian rice have been developed by a cross between Japanese species and Indian species of rice.
So, the correct answer is ‘ Oryza sativa japonica and Oryza sativa Indica ’

Note: By using plant breeding techniques, semi-dwarf varieties of wheat called sonalika and Kalyan Sona which are high yielding and resistant to diseases are produced by Norman E. Borlaug in Mexico. Himgiri is the variety of wheat developed for resistance against leaf and stripe rust disease.