Evolution and breeding in rice crop.pptx

Evolution and breeding in rice crop

1. JAI NARAIN VYAS UNIVERSITY JODHPUR DEPARTMENT OF BOTANY SEMINAR TOPIC -: EVOLUTION AND BREEDING IN RICE SUBMITTED TO -: DR. BHANARAM JI GADI SUBMITTED BY -: KAMLESH KUMAR

2. Introduction Rice is grown on all six continents in the world except Antarctica. The two cultivated rice species are   Oryza glaberrima , commonly known as African rice, and  Oryza sativa  L ., commonly known as Asian rice, which has two major subspecies ( japonica and indica ). Cultivated rice is a diploid species (2n=2x=24 ) with basic chromosome number of 12. Twenty-one different wild varieties exist. Rice is one of the most important food crops in the world and is the staple food in numerous countries, particularly in Asia.

3. Origin Rice has three distinct cultivated species and 21 different wild varieties. Information on the origin of glaberrima and the two oryza subspecies is as below: Oryza glabberima – domesticated in West Africa between about 1500 and 800 BC or about 2,000-3,000 years ago (Linares, 2002). Oryza sativa japonica – domesticated in central China about 7000 BC or about 8,200-13,500 years ago . Oryza sativa indica – domesticated in the Indian subcontinent about 2500 BC .

4. Wild Ancestor of Rice The wild ancestor of cultivated rice ( Oryza rufipogon ) existed over a broad range of geographic regions across Asia. Domestication of  O. rufipogon  in response to human selection resulted in complete transformation of morphological and physiological traits of the plant. Consequently, cultivated rice ( O. sativa ) displays reduced dormancy, grain shattering and outcrossing, and reduced loss of pigmentation in the hull and seed coat.

5. Transformation to Cultivated Rice Fig. Transformation of wild O. rufipogon to cultivated O. sativa due to । domestication of rice. a) Panicle – wild O. rufipogon ; b) Seeds – wild O. rufipogon ; c) Panicle – cultivated O. sativa ; d) Seeds – cultivated O. sativa . T here is a better synchronization of tiller development and panicle formation in modern rice cultivars along with an increased number of secondary panicle branches (Fig. 2), higher grain yield and weight, and improved photoperiodic response.

6. Breeding Methods 1. Selection Methods Mass selection is the oldest selection method of plant breeding and probably the most used in plant breeding over time. It is the widely used in rice breeding. The progenies of the best population are expected to be superior to the progeny of a random sample of the population in this method. However, there is difficulty in evaluating the efficiency of mass selection methods is that there is no information about the genotype of the individual selected. In rice verity like IR8 was p developed and improved through this method ). IR8 is the first high-yielding modern rice cultivar, was released by IRRI in 1966. It was the start of the “green revolution” in Asia.

7. Hybrid Rice Heterosis in rice was reported by Jones in USA as early in 1926 and Ramaiah in 1933.
But the research work on hybrid rice was initiated in 1964, in China by Yuan Long Ping (Father of hybrid Rice).

8. Single line method of rice breeding • Vegetative propagation• Micro propagation - Anther culture• Apomictic lines

9. Two line system in Hybrid Production Photoperiod sensitive gen et ic male sterility (PGMS): 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. Temperature sensitive gen etic male sterility (TGMS): It is sterile when temperature exceeds 32°C/24°C (day/night) and becomes fertile when the temperature is below 24°C/18°C (day/night). However, in few cases, sterility is observed at lower temperatures and fertility is observed at higher temperatures. Such type of male sterility is referred to as 'Reverse TGMS type .

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