A Comparison on the Effects of Radiations and Chemical Mutagens on Chromosome Association and Chiasma Frequency in Diploid <i>Sorghum</i>

Abstract

Grains of S. purpureosericeum were treated with X rays and with gamma rays and were soaked in solutions of ethyl methanesulphonate and diethyl sulphate. Grains soaked in a buffer solution served as the control. Only bivalents were observed in PMCs of the controls whereas quadrivalents and univalents were also found in the PMCs of the M1 generation of treated plants. Radiation induced a higher frequency of translocations as well as univalents compared with the chemical mutagens. There was, in general, a decrease in the frequency of bivalents with three chiasmata in the treated plants compared with the controls. However, a slight increase in chiasma frequency was evident after treatment with 9.70 mM ethyl methanesulphonate. In contrast, the number of bivalents with a single chiasma increased in the treated plants compared with the controls.