GENETIC-ANALYSIS OF SEMIDWARF MUTANTS INDUCED IN INDICA RICE (ORYZA-SATIVA L)

The mode of inheritance of five semidwarf (SD) mutants and allelic rel ationship with DGWG (sd1) locus was studied. The five SD mutants viz., Basmati 370 (SD1), Basmati 370 (SD2), Basmati 370 (SD3), TCA 2 (SD) a nd TCA P2-5 (SD) when crossed with their tall parents exhibited monoge nic inheritance of 3 tall: 1 semidwarf in the F2 progenies. The SD mut ants were also crossed with semidwarf varieties (DGWC and Bala) posses sing sdl gene. Crosses between Basmati 370 (SD1) x Bala, Basmati 370 ( SD3) x Bala and TCA 2 (SD) x DGWG produced tall F1 hybrids and in F2 g eneration, modified dihybrid ratios (9 : 6 : 1 and 9 : 7) were observe d indicating that the mutants Basmati 370 (SD1), Basmati 370 (SD3) and TCA 2 (SD) are non-allelic to sdl gene. Whereas, the mutants Basmati 370 (SD2) and TCA P2-5 (SD) when crossed with Bala produced semidwarf F1 hybrids and in F2 generation, segregation for plant height was not observed indicating that these mutants are allelic to sd1 gene. The th ree non-allelic SD mutants identified in the present study can be used in rice breeding as alternative gene sources for semidwarfism.