| Means of spike length and of the first internode below the peduncle showed
no significant differences between concentrations of NaN3 or
MNH, except that NaN3 treatments reduced internode length in
M1 plants by 3cms (mean internode length for control 31cm and
27, 28, and 27cm for 1.0, 1.5 and 2.0 g/l, respectively). With increasing
concentrations of NaN3, a reduction in both seed set and kernel
weight occurred in M1 plants but no differences were found between
concentrations of MNH for either character in M1 or M2
generations (Fig.2). In general, seed set and kernel
weight showed the greatest range of variability in the M1 generation
due to different concentrations of NaN3. This study showed that MNH was an ineffective chemical for inducing genetic variability in triticale at these concentrations. Sodium azide had a depressing effect on all characters studied in the M1 generation but M2 plant character means were generally similar to the controls. However, two important yield components (seed set and seed weight) showed reduced mean values from each set of NaN3 treatments in the M2 generation with seed set suffering the most. The much larger variation for seed set caused by the NaN3 treatments in both generations than that occurring in the controls, indicates that selection for higher fertility might be feasible, especially in light of the narrow range and smaller effect on kernel weights. In most treatments, NaN3 did increase the genetic variability in the M3 generation as many individual plants of less than 100 cms in height have since been selected. Because triticale is an allopolyploid, it may be that full expression of genetic variability is delayed until M3 or later generations. In this study, we did not observe any chlorophyll mutations in either M1 or M2 generation which were reported to be numerous in NaN3 treated barley seeds (NILAN et al. 1973). Literature Cited BROCK, R.D. 1971. The role of induced mutations in plant improvement. Radiation Botany 11: 181-186. GREGORY, W.C. 1965. Mutation frequency, magnitude of change and the probability of improvement in adaptation. Radiation Botany 5: 429-441. KONZAK, C.F., R.F. NILAN, J. WAGNER and R.J. FOSTER. 1965. Efficient chemical mutagenesis, p. 49-69. The Use of Induced Mutation in Plant Breeding, Pergamon Press, Oxford. KONZAK, C.F. 1973. Using mutagens and mutations in wheat breeding and genetic research. Proc. Fourth Int. Wheat Genetics Symp., Univ, of Missouri. Columbia, Mo., Aug. 6-11., p. 275- 281. NILAN, R.A., E.G. SIDERIES, A. KLEIHOFS, C. SANDER and C.F. KONZAK 1973. Azide-a potent mutagen. Mutation Research 17: 142-144. VAGERA, J. 1969. The effect of N-nitroso-N-methylurea, Buthylmethane Sulphonate, and X-rays on the germination and production of chlorophyll mutations in Einkorn wheat. Biologia Plantarum 11: 408-416. VAGERA, J. 1971. Changes in the variability of quantitative characters in M2 induced in Einkorn wheat by N-nitroso-N-methylurea and X-rays. Biologia Plantarum 13: 279-289. (Received September 20, 1975) |
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