| Results and Discussion Plant height in all the mutant populations was significantly (P>0.05, 0.01) reduced from that of controls whereas, culm diameter and tiller per plant revealed significant (P> 0.05, 0.01) increase in mutants, except mutant No. 7 of C-591; mutant No. 10 and 44 of Nayab and mutant-13 of Indus-66 for culm diameter and mutant No. 28 of C-591, mutant No. 10 of Nayab and mutant No. 37 of Indus-66 for tillers per plant (Table 1 and 2). These mutant strains showed an increase over respective controls, but this was not statistically significant. Significant shift in mean values of these agronomicaly important traits is in good agreement with the findings of LARIK (1975a, b; 1978) and SIDDIQUI (1972). The mean height of the mutants of Nayab and Indus-66 were reasonably homogeneous except mutants of C-591, in which mutant No. 28 was clearly taller than the rest of mutants whereas, mutant No. 38 was dwarf which showed a reduction of 18 cm in plant height along with an increase of 0.6 microns in culm diameter. A combined persual of the effects of data with respect to ethyle methane sulphonate (EMS) upon plant height and culm diameter would reveal that if the height of plant declined, the girth of culm increased. Reduction in plant height, increase in culm diameter and tillers per plant in wheat, Triticum aestivum are desirable attributes from breeders point of view as these are associated with stiffness of the straw, efficient utilization of nitrogen, loding resistance and grain yield (HEAR and WETTSTEIN, 1973; LARIK, 1978; SIDDIQUI, 1972) The highest genotypic coefficient of variation (18.26%) for plant height and culm diameter was given by mutant No. 37 of Induss-66, which also had the highest heritability (48.59%) and genetic advances (21.84%). This indicates the potential for the improvement and greater gains from selection for these characters are anticipated in mutant No. 37 (CHAFOOR ARAIN, 1973, PATIL, 1972). Low heritability estimates, genetic advance and genetic variation was given by mutant No. 7 of C-591 for culm diameter and mutant No. 13 and 37 of Indus-66 for plant height and tillers per plant respectively. These results indicate that the character could be transmitted to future generation however, no significant gain could be achieved through selection in early generation. The magnitude of these estimates among the treated lines of different cultivars varied widely (Table 1 and 2). The present studies conclude that from breeders point of view selection for superior genotypes for agronomically important traits can only be made among mutant strains for those attributes which reveal high heritability, values and high genetic advance. The present studies have also provided an evidence on the induction of genetic variability connected with these quantitative characters among different mutant strains of wheat cultivars derived from gamma rays and EMS-treatment. The genetic variability thus, induced can effectively be exploited for evolving mutant strains possessing desirable attributes. Literature Cited Allan, R.E and J.A. Prtichett. 1973, Crop Sci., 13: 597-599 Ghafoor Arain, A. 1973. Ph. D. Thesis submitted to Univ. Adealide, Australia, pp. 1-63 Haar, V., and Von Wettstein, D. 1973. Barley News Letter 2 Joppa, L.R. 1973. Crop Sci., 13: 743-746 Larik, A.S. 1975a. Genetica Agraria Vol XXIX-Fasc 3-4: 241-250 Larik, A.S. 1975b. Genetica Polonica Vol. 16, No.2: 153-160 Larik, A.S. 1978. Genetica Agraria (in press) Lerner, J.M. 1954. Genetic homeostasis. Oliver and Boyd, London Patil, S.H. 1972. Indian J. Genet. Plant Breed. 32: 451-459 Romero, G.E. and K.J. Frey. 1973. Crop Sci., 13: 334-337 Shukla, G.C. 1974. Int. Rice Comm. Newsletter., 23: 29-40 Siddiqui, K.A. 1972. Herditas, 71: 289-300 Vogal, O.A.: J.C. Craddock; C.E. Munir; E.H. Everson and C.R. Rohde. 1956. Agron. J., 48: 76-78 |
| <-- Back |