Induced polygenic mutations in wheat (Triticum aestivum L.)

IRFAN A.KHAN

Nawab Shah Alam Khan Post-Graduate centre, Anwarut-Uloom College, Hyderabad, India

Bread wheat being a polyploid, offers many opportunities of exploitation of mutations, recombinations and of increasing genetic variability in quantitatively inherited characters (LARIK 1975). From the work already reported by several authors on this crop (BHATIA & SWAMlNATHAN 1962 BOROJEVIC 1969, BOROJEVIC & BOROJEVIC 1972, LARIK 1979, LARIK et al. 1980 CHOWDHARY 1982), it is now quite clear that polygenic mutation results in the release of considerable variability in irradiated populations. However, informations are scanty about the influence of chemical mutagens on quantitative characters particularly in wheat, compared to that of irradiations. It is quite likely that chemical mutagens may provide a better understanding since they induce a much higher mutation rate and causes less chromosomal disturbances than do radiations (JANA & ROY 1973). In view of above considerations, the present investigation has been carried out to induce mutations by EMS in four quantitative characters of wheat variety, Bansi.

Materials and Method

Dry seeds of a variety of wheat, Bansi were pre-soaked in distilled water for 9 h. and then treated with 0.1 to 0.4% ethyl methane sulfonate (EMS) for 6 h. at a constant room temperature of 20 + or - 1C. The treated seeds were washed thoroughly in running tap water for half an hour and sown in the field in randomized complete block design with three replications. In each replication, five lines of ten seeds each were allotted for each treatment and control with a inter-row distance of 1 ft. and inter-plant distance of 15 cm. The data on four quantitative characters i.e. no. of fillers, spike length, spikelets per spike and total plant yield were collected from each individual plant separately.

For studying the polygenic variability in M₂ and M₃ generations, a random seed sample of 300 seeds was sown in randomized complete block design in three replications with the same distance as kept in M₁ generation. Data on individual plant of these four quantitative characters were collected and analysed statistically. The genetic parameters were calculated to estimate the extent of genetic variability in the treated populations. The expected genetic advance (Gs) with 5% selection intensity was calculated according to the modified formula (KHAN 1983),

Gs = k.delta p.h²

where delta p = phenotypic standard deviation of the mean performance of treated population, h² = broad-sense heritability and k = 2.06 constant for selection differential.

Table 1. Estimates of mean values (X), coefficient of variation (phenotypic and genotypic), heritability (h²) and expected genetic advance (Gs) in the M₂ generation

Table 2. Estimates of mean values (X), coefficient of variation (phenotypic and genotypic), heritability (h²) and expected genetic advance (Gs) in the M₃ genaration

--> Next