|Keywords (Extracted from title, table of contents and
abstract of thesis)|
Effects, Mutagens, Genetic,
asyndatic, Parameters, Soyabean, Sporocytes, microsporogenesis
Studies were conducted to record the comparative effect of various doses of gamma rays on the chromosomal behaviour during microsporogenesis and some genetic parameters
of soybean (Glycine max (L) Merril.). Seeds of Swat-84 variety
were irradiated with 5, 10 and 22 Krad and during microsporogenesis it was observed that,the control plants behaved as normal diploid with 2n = 40 and 20 by 20 disjunction. Sporocytes from the 5 Krad plant had meiotic anomaly of the frequent occurrence of asyndatic chromosomes in 32% cells. The range of asyndatic chromosomes was 2-4 per cell. Sporocytes of the plant raised from 10 Krad irradiated seed showed the presence of univalents, trivalents and quadrivalents in 20, 25 and 45 percent cells. Whereas, the plant raised from seed treated with 20 Krad showed 50, 23.07 and 61.53 percent cells with asyndatic chromosomes, trivalents and quadrivalents, respectively. The increased radiation doses increased meiotic anomalies associated with a reduced pollen fertility.
Among the three soybean varieties, Swat-84 was comparatively more radio resistant, then the Epps, whereas, Lakota was the least radio resistant variety among them.
Moreover, Swat-84 proved to be the out yielding genotype among the three cultivars used during the present investigations.
Statistical analyses of the data revealed highly
significant differences of radiation doses for germination percentage, flower initiation, primary and secondary branches per plant, pod length, number of pods per plant, 1000 grain weight, grain yield per plant and plant height. Significant
differences of varieties were also recorded in germination percentage, primary and secondary branches per plant, pod length per plant, number of pods per plant, 1000-grain weight, grain yield per plant and plant height varieties into doses
interaction was significant for plant height, pods per plant, 1000-grain weight and grain yield per plant.