Abstract:
Natural ultra short mutant in rice has recently been identified in the rice field at CIC
farm, Palwehera. One F2 population of the cross between Dwarf mutant and Bg300-and
three F2 populations each, from the cross between Dwarf mutant and Bg 300, Dwarf
mutant and Bg 357 and Dwarf-mutant and CIC 300 were planted . At maturity, Plant
height panicle length, number of spikelets/panicle, filled grain % and maturity duration
each plant of the ¥2 population of the cross between Dwarf mutant and Bg 300 . To
confirm the rest of other three F2 populations^ only the number of dwarf and tall plant
types were identified as the time did riot permit to wait until maturity to measure other
characteristics. Different measurement categories in each characteristic and the
observed F2 segregation ratios within each characteristic, were identified. Chi-square
analyses were performed on F2 data to test goodness of fit to expected , segregation
ratios. All observed F2 segregation ratios showed a good fit to 13 Tall: 3 Dwarf (5% at
one degree of freedom). This newly identified dwarf rice mutant was found to be
controlled by three genes: which the expression is suppressed by a third dominant
inhibitory gene. Panicle length, number of spikelets/panicle, filled grain % and maturity
duration were also found to be as exactly same as the inheritance of ultra short plant
type and all these characteristics were found to be controlled by the same genes that
control ultra short plant type probably showing pleiotropyc gene effect. Short panicles,
low number of spikelets/panicle, low filled grain % and long maturity duration were
found to be genetically associated with ultra short rice plant.
