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EMS treatments of inbred lines of rye Arne MUNTZING and Sunando BOSE Institute of Genetics, Lund, Sweden and Bose Research Institute, Calcutta-9, India In September 1964 dry seeds of three different inbred lines and population plants of the rye variety Steelrye were treated with EMS solutions, the concentrations of which ranged from 0.5 to 2.5 per cent. After treatment for three hours at 18C there was an interval of about 20 hours before the seeds could be sown. Only seeds treated with 0.5 and 1.0% EMS germinated and of the resulting seedlings most of those from the stronger treatment did not survive the winter. The treatments, including two more inbred lines, were repeated in the following year. This time the seeds were sown immediately after treatment and in this way germination, seedling vigour and survival were sufiiciently good to result in a larger number of M1 plants and M2 progenies. The following general effects of the treatments were observed: (a) Strong concentrations of EMS reduce germination significantly, whereas weaker doses have little or no effect. (b) Seedling height after treatment and seedling survival vary in proportion to the concentration of the EMS solution. (c) In M1 seed set was reduced, the degree of sterility again varying as the strength of the EMS treatment. (d) The stronger concentrations of EMS resulted in obvious decreases of plant weight in M1. On the contrary, there was an indication that plant weight was stimulated by weak concentrations. (e) M2 seeds derived from the strongest EMS treatments germinated less well than those from weaker concentrations. The following differential effects of the treatments were observed: (a) The population material of Steelrye was clearly more resistant to EMS treatments than the inbred lines. This was found to be true of the germination of the treated seeds as well as seedling height and seedling survival. (b) The inbred lines, which may be considered to be perfectly homozygous after a long period of inbreeding, were found to differ in their frequencies of spontaneous chlorophyll mutations. They also reacted differently to the EMS treatments with regard to primary effects as well as to the frequencies of induced mutations. Most probably, each inbred line has its specific norm of reaction to treatments with EMS. (Received January 8, 1968) |