Characterization and Genetic Analysis of a Very High Tillering and Dwarf Rice (oryza Sativa L.) Mutant

Characterization and Genetic Analysis of a Very High Tillering and Dwarf Rice (Oryza sativa L.) Mutant. (August 2008) Dhananjay Mani, B.Sc. (Hons)., Punjab Agricultural University, Ludhiana, India Co-Chairs of Advisory Committee: Dr. Rodante E. Tabien Dr. Scott A. Finlayson This study focused on characterizing and determining the inheritance pattern of very high tillering and dwarf traits of a rice mutant. To characterize the new mutant, field phenotyping studies, and response of two mutant lines (M-13662 & M-13684) to three levels of nitrogen (179, 202, 224 kg ha -1 ) and five planting densities (1, 2, 3, 4, 5 plants hill -1 ) in greenhouse conditions were conducted. A separate study was carried out to determine the response of the two mutant lines to gibberellic acid (GA) application. The mutants were 50-55 cm tall and produced 89-121 tillers plant -1 at harvest. Dwarfness of the mutants was due to average shortening of the top four internodes as well as compression of 2-3 basal internodes. The first tiller emerged at the 4 th leaf stage whereas no tiller was observed in semi-dwarf rice cultivar, Cocodrie. Results showed that the production of high tiller numbers was the result of the release of axillary buds from a dormant stage rather than the initiation of additional axillary buds. The mutants were late maturing than controls (Cocodrie & Zhe733). The panicles were very short (10-12 cm) and had 25-30 small grains. The majority of tillers of the mutants followed the dn-type dwarf pattern based on Takeda’s classification, but a few plants had a