| Results and Discussion The present studies were carried out to measure the amount of induced variability in different quantitatively inherited characters and to recognize the potential of EMS treatment. Spike length and spikelets per spike are the most important yield components as they determine the ultimate crop yield (LARIK 1979). Spike length increased in both M2 and M3 generations. Mean values of spikelets per spike also increased significantly with the exception noticed at 0.4% of EMS in both the generations. The increase in the number of spikelets may be ascribed to the increased frequency of supernumery spikelets (MACKEY 1954, SCOSSIROLI & PALENZONA 1961). On the other hand, number of tillers increased significantly. Yield is a dependent character, and is the result of all the biological processes going on during the growth and development of plant (SCARASCIA-MUGNOZZA 1964). The general trend of reduced yield among the mutagenic treated material could be due to pleiotropic effects (GAUL 1977) on other characters. However, in the present study, yield per plant increased almost in all the treatments except 0.3% in M2 generation. The increase was more in the M3 as compared to M2, may be due to the increased recombination and elimination of cytological variants. As might be expected, the induced variability in the mutanized populations was higher than the control populations for almost all the characters measured. This is in agreement with the observations of other workers (MATSUO & ONOZAWA 1961, YAMAGATA 1964). However, there were differences for different traits in both the generations. This differential response has also been reported by GOUD (1967). The estimates of heritability and expected genetic advance increased for all the characters in the treated populations. Number of tillers showed high values of heritability and genetic advance in the M2 generation as compared to M3, indicating that the selection for this character win be more effective if it is applied in early generations. On the other hand, spike length, spikelets per spike and yield per plant showed high estimates of heritability and genetic advance in the M3 generation indicating that these characters can be transmitted to future generations and significant gain could possibly be achieved if selection is made at M3 generation because of stabilization. The present studies have provided an evidence on the induction of genetic variability for yield and yield components of this crop. It might be possible to concentrate on the exploitation of the variability for these characters for the improvement of yield. References BHATIA, C. & M. S. SWAMINATHAN 1962. Z. pflangzenz. 48: 317-326. BOROJEVIC, K. 1969. Japan J. Genet. 44: 404-416. BOROJEVIC. K. & S. BOROJEVIC 1972. Induced mutations and plant improvement, IAET/FAO, Vienna 1970, pp. 237-249. CHOWDHURY, R. K. 1982. Wheat Information Service 54: 27-31. GOUD, J. V. 1967. Rad. Bot. 7: 321-331. GAUL, H. 1977. Manual of mutation breeding, IAET, Vienna, 87-96. JANA, M. K. & K. RoY. 1973. Rad. Bot. 13: 245-257. KHAN, IRFANA. 1983. Canadian J. Genet. Cytol. 25: 298-303. LARIK, A. S. 1975. Genetica Polonica 16: 153-160. LARIK, A. S. 1979. Wheat Information Service 49: 70-73. LARIK, A. S., K. A. SIDDIQUI & A. H. SOOMRO 1980. Pak. J. Bot. 12: 31-41. MACKEY, J. 1954. Acta Agric. Scand. 4: 549-557. MATSUO, T. & H. ONOZAWA 1961. Effect of ionizing radiations on seeds, IAEA, Vienna, 493-501. SCOSSIROLI, R. E. & D. PALENZONA 1961. Atomic Energy Agency Vienna, 373-386. SCARASCIA-MUGNOZZ, G. T. 1964. Rad. Bot. 5: 537-538. YAMAGATA, H. 1964. Gamma Field Symp. 3: 31-47. |
| <-- Back |