| Results and Discussion The effects of individual and combined treatments of sodium azide and hydrazine hydrate on different M1 parameters are depicted in Table 1. It was observed that individual and combined tratments of azide and HZ produced reduction in seed germination, seedling growth, pollen and seed fertility and survival at maturity in both genotypes except in variety Al-Samma where sodium azide 0.0001 molar concentration displayed some improvement in all the parameters studied. The reduction was found to be dose dependent; it increased consistently with increase in the concentration of the mutagen applied. Previous reports (SHARMA et al. 1979; SlNGH et al. 1978) have also shown linear relationship between the dose of the mutagen applied and the parameters studied. However, seed germination was adversely affected in combination treatments than in the individual treatment, thus indicating a negative synergistic effect by enhanced toxicity. It was noticed that HZ was relatively strong mutagen than the azide. Genotypes displayed remarkable differences in their response to individual and combined treatments. The highest concentration apparently caused highest biological damage (Table 1), which indicate the efficiency of highest concentration. However, the efficiency of the mutagen is not only dependent on the concentration alone but also on other variables such as presoaking time, duration of the treatment and pH of the mutagen solution. Similar reduction in seed germination was reported by AWAN et al. (1980) in rice and NILAN et al. (1976) in barley and BHASHARAM and SWAMINATHAN (1961) in wheat and barley. Since no cytological examination of primordial root tips were undertaken for these treated seeds, no precise interpretation, regarding the intrinsic events contributing this phenotypic manifestation, is possible. However, for this depreciated germination, one is allude to conclude that embryo which might have been disturbed by mutagen effects made slow recovery. Such plant injury effects may be due to physiological or chromosome mutations. According to GAUL (1977), physiological damage has probably both chromosomal and extra-chromosomal origin and the separation of these two causes is usually not possible. It may be noted that in variety Al-Samma lower concentration (0.0001M NaN3) has shown stimulatory effect in all the parameters and also in variety Hinta Madina lower concentration caused relatively less damage as compared to the higher concentration. This shows that the recovery after primary injury due to toxic effects of lower concentration was better, while the effects of higher concentration persisted up to the adult plant stage as was evident from the survival and seed fertility at maturity (Table 1). Survival percentage displayed further decline . Here also both genotypes exhibited greater sensitivity. Variety Hinta Madina showed higher germination and better survival than variety Al-Samma. This probably is due to its genetic makeup and greater tolerance. The two genotypes under investigation do not show same degree of response to both mutagens. Al-Samma was found to be more sensitive than Hinta Madina. Already there exists much evidence that genetic differences even though they are as small as single gene difference, can produce significant changes in mutation expression (SMITH, 1958; NILAN, 1954) and will show different degree of response. |
| <-- Back | | | --> Next |