Showing papers on "Mutation breeding published in 1973"

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)1 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.

Increasing the Effectiveness, Efficiency, and Specificity of Mutation Induction in Flowering Plants

Abstract: Numerous agents are now available for inducing mutations and chromosome aberrations for a variety of investigations in plant genetics, development, and evolution and in plant breeding (mutation breeding). These include the widely used physical mutagens X-rays, γ-rays, neutrons, and β-rays; the potent alkylating compounds ethyl methanesulfonate (EMS), diethyl sulfate (dES), and ethyleneimine (EI); and nitroso compounds, nitroso ethylurethane (NEH), nitroso methylurethane (NMU), ethyl nitrosourea (ENH), and methyl nitrosourea (MNH). Much of the recent research on induced mutation in plants has been reviewed by Auerbach and Kilbey (4). Thus information in this chapter will be largely confined to experiments with flowering plants.

Improvement of mung bean through induced mutations

Abstract: Two mung varieties were treated with gamma rays. The radiation treatments have been effective in inducing considerable variation for a number of characters of economic value e.g. yield/plant, grain size, number of pods/plant, days to flower and protein content. The quality of proteins was also changed, some of the M2 progenies showed a greater range of variation in the content of methionine and tryptophan. The treatment with 70 kr. was found to be more effective than 30 kr. But the 30 kr. treatment had a stimulating effect on plant growth which was associated with low seed yield. All early maturing mutants were found to be less seed yield productive. The present study has indicated that mutation breeding results in an increase in variation for all quantitatively inherited characters but there was a decrease in the general mean of the irradiated population, with some exceptions.