**2.1. Plant material and application of induced mutagenesis**

Grains of spring bread wheat variety cv. Eritrospermum-35 (*Triticum aestivum* L.) were irradiated by doses of 100 Gy and 200 Gy from a Co60 source at the Kazakh Nuclear Centre. Grains were planted immediately after irradiation in order to obtain M1 plants. The M1 generation was grown in the experimental field of the Kazakh Institute of Agricultural and Farming near Almaty according to the standard agricultural practice. Single spikes were harvested from each plant in order to develop the M2 generation. Selection of the best lines from M1 to M5 was carried out based on individual plants. The plants of M3 and M4 generations were planted in randomized blocks in three replications. The best lines were tested with their parent variety in order to select advanced mutants. The selection criteria for these lines were GWS and GWP, which were applied in the M3 and M4 generations (2011 and 2012) and based on the values for the parent cv. Eritrospermum-35 grown under the same trial conditions. In 2011 and 2012, the parent line had a mean of GWS of 0.79 ± 0.24 g and 0.80 ± 0.26 g, a mean of GWP of 2.06 ± 06 g, and 1.41 ± 0.43 g yield values, respectively. The threshold criteria for selection in the M3 and M4 generation were GWS >1.1 g and GWP > 2.2 g for mutant lines. Grains of the best mutants were individually selected in each generation. After harvesting the M5 plants, 15 lines from the original 100-Gy radiation dose were selected. These lines were numbered as follows: 105(1), 108(1), 113(1), 113(5), 118(1), 118(2), 118(3), 135(1), 136(1), 138(6), 140(2), 140(3), 140(4), 232(1), and 242(2)). Another 15 lines were selected from the 200-Gy radiation dose, which were numbered: 144(1), 144(2), 149(2), 150(7), 152(1), 152(4), 152(5), 152(6), 152(7), 152(8), 153(4), 153(5), 153(6), 153(7) and 153(8).

Samples of grains of each mutant line and the parent were tested. Grain samples from each mutant line, together with the parent Eritrosperumum-35, were planted in a field trial for further evaluation. Each line was grown in three replicate three-row plots, 2 m long, 1.20 m wide with 20 cm between rows, and 30 seeds planted per row. The trial was managed according to the local recommendations for agronomic practices [33]. The following productivity parameters, GWP, GNS, GWS, and TGW calculated as the mean weight of three sets of 100 grains per line were estimated.
