Studies on the procedure of mutation breeding with, six-rowed barley. : I. The methods of procedure in X1 and X2 generations.

The methods of mutation breeding were applied on six rowved barly in three ways. The dormant seeds were treated with 15 Kr of X-rays. Method A : After 3 ears were havested from each X1 Plant and one grain was removed from each ear, these grains were planted in bulk at X2 Mlethod B : After one ear was harvested from each Xl plant, the grains were planted separately as ear progenies at X2Method C : After 3 ears were harvested from each Xi Plant, the grains were planted separately as plant progenies at X2 Method A was compared with B and C. The eharacters mainly analyzed were earliness and stems;shortness. The selection of such aberrants was carried out in X2 (Table 1), and these were confirmed as mutants in X3 (Tables 2 and 3) . In the case of method A-ll (Table 1), selection was made by measuring stem length at X2 generation. In the case of other methods, selection was made by observation. 1) By using method A, the mutant types found n X2 Were more frequently observed compared with the other two methods and the mutant much deviated from the parent type were involved.This result was compatible with the theoretical consideration of YOSHIDA (1962). 2) Much better selection of short stem mutants was made in X2 by method A (I+II) than by methods B and C. This result demonstrates that the individual selection using this measurement was made much better than the pedigree selectian through observation.