Cytogenetical studies on the autotetraploid plant of rice, oryza sativa L

A cytogenetic investigation of autotetraploid of rice was attempted. The five autotetraploids of rice varieties, (Norin 18, Jinheung, Shinriki, Omachi and Sekitori) were used in this experiment. The morphological effect of autotetraploidy was increase in the size of spikelet, leaf and awn. The pairing mode in the first metaphase of meiosis was 11 IV+2 II for Norin 18, 10 IV+4 II for Jinheung, Omachi and Sekitori, and 9 IV+6 II for Shinriki. The average number of quadrivalents per cell was 8.8 to 9.4. It was found that the non-simultaneous divisions occurred among daugther cells, and chromosomes in anther. The cell number during meiosis was not so much as that of diploids.