Evaluation of breeding semidwarf rice by induced mutation and hybridization

Abstract

Semidwarf indica varieties of rice (Oryza sativa L.) were developed by induced mutation. They generally have a yield capacity equal to that of the semidwarf varieties (T(N)1, IR 8 and others) selected from hybridization . Genetic studies showed that semidwarf genes induced in the mutants and spontaneous ones in existing varieties are at the same locus . These semidwarf mutants, selected in Taiwan and from an American long-grain variety, Centura Patna 231, were compared with their parents, the semidwarf variety Dee-goe-woo-gen, T(N)l and IR 8 . The semidwarf mutants average about 35 % shorter than their tall parents . The plant height is reduced by shortening five internodes from the top, while panicle length is not affected . The mutants, Dee-geo-woo-gen, and improved short-statured varieties had similar patterns of internode elongation . The mutants derived from varieties sensitive to photoperiod have lost the sensitivity . One more crop can be grown within a year . All induced and hybrid-derived semidwarf varieties were highly susceptible to bacterial leaf blight when Xanthomonas oryzae was inoculated although some of their parents were moderately resistant . The mutation rate from irradiation of this semidwarf gene was estimated to be 0 .1 % in I-kung-bau, a native variety of Taiwan. This particular type of mutation has not yet been reported in japonica varieties . However, several promising strains with reduced plant height, earlier maturity and more grain yielding were recently obtained from the California japonica variety, Calrose, by X-irradiation . The merits of mutation breeding in rice are discussed .

Induced Mutations in Plant Breeding

“…In other genotypes of this group the grain size is reduced. In some mutants the dwarfism is combined with earliness (Hu 1973) or with an increased protein content (Misra et al1971). In Japan, ten promising mutant lines with stiff straw, high yield, and excellent cooking quality of the grain were selected from a mother variety with low lodging resistance (Samoto 1975).…”

“…In Japan, ten promising mutant lines with stiff straw, high yield, and excellent cooking quality of the grain were selected from a mother variety with low lodging resistance (Samoto 1975). Thus, it may be possible to grow one more crop within a year in the respective regions (Hu 1973). The best short-culm mutant of a French collection had a better lodging resistance and a 50% increased yield, but the plants were 6 days later and the milling quality of the grains was insufficient (Marie 1967).…”

“…A mutant of Corchorus capsularis, in spite of maturing 40-50 days earlier, shows an increased fiber yield (Singh 1971). Its Majumder 1965Kawai 1967Marie 1967Ree 1968Viado 1968Miah and Bhatti 1968Siddiq and Swaminathan 1968Tanaka 1968Takenaka 1969Kawai 1969Kawai and Narahari 1971Miah et al 1970Basu and Basu 1970Haq et al 1971Li et al 1971Miah and Awan 1971Mikaelsen et al 1971Misra et al 1971Pawar 1971Reddy and Reddy 1971Reddy 1975Hu 1973Ram 1974Sharma et al 1974Reddy et al 1975Roy and Jana 1975Ismachin and Mikaelsen 1976Rutger et al 1976--Simon and Sajo 1976Ismachin Kartoprawiro 1977Mallick 1978 Kau11978 Dasgupta 1979Ismail and Ahmad 1979Afsar et al 1980 Mutagens 32p Gamma rays X rays, gamma rays, EMS X rays X rays, gamma rays Gamma rays Gamma rays, EMS, NMU Khvostova 1967 Gamma rays aestivum -Sawhney et al 1971 Gamma rays An early ripening mutant with good yield - Mehta 1972 Gamma rays, EMS, 18 mutants; 3-15 days earlier NMU - Kalashnik et al 1972 1 dominant mutant - Khan 1973 Neutrons Strain "Rageni"; 3 weeks earl...…”

Photoperiod sensitivity in three rice crosses

“…Genotypes with a dominant allele are photoperiod sensitive, and homozygous recessive genotypes are insensitive. Some workers have reported a positive association between photoperiod sensitivity and plant height (RAMIAH, 1933;ESCURO, 1960;Hu, 1973). Some workers have reported a positive association between photoperiod sensitivity and plant height (RAMIAH, 1933;ESCURO, 1960;Hu, 1973).…”

“…Some cases of recessive alleles conditioning photoperiod sensitivity have been reported (SAMPATH & SESHLJ, 1961;KLJRIYAMA, 1965;SIMBE, 1982). Hu (1973) suggested that the genes inducing short stature may confer insensitivity to photoperiod. Hu (1973) suggested that the genes inducing short stature may confer insensitivity to photoperiod.…”