X-ray induced mutation tn barley.

The X1 and X2 generations of X-rayed barley seeds -were investigated and the following results were ob'tained . 1 . The difference of fertility exists arnong, spikes, of an individual plaat in X1 generetion. The progenies, , of spikes with" normal fertility in X1 genetation may, often segregate into fertile and partially sterile plants in X2. On the other hand, partially sterile spikes may often produce fertile plants only. 2 . Seventeen from sixty spikes obtained frorn eighteen X1 plahts segregated structura' hybrids ; fourteen of them havd a ring of four chromosomes, two have .a ring of six and 'one has two rings of four. Seed Ifertilities of plants with a ring of four are 51. 5-74.5%, plants with a ring of six are 47.5 and 53.2%and plants with two rings of four are 48. 0%. 3 . One triploid plant and several mutants, which are male sterile, Iiguleless and short culmed, are detected . Possibility of applying BURNHAN'S multiple translocation method in barley is discussed . Cqnsidering the suspected sterility of translocation heterozygotes, a multiple translacation type with a ring of eight and a ring of six is supposed to be more applicable than that With a ring of fourteen. Procedures to iuduce such a multiple translocation type are suggested, Where repeating X-ray treatment of translocation honcLozygote might be adopted to accumulate translocatians step by step.